ZENVY BEAUTY RESEARCH · REPORT 01
The UK Hair Porosity Report 2026
In February 2026 we asked 1,000 UK women to run a six-signal porosity test on their own hair, then followed 416 of them through a 90-day study to find out what happens when a routine finally matches the reading. This is what Britain’s hair is doing: by porosity band, by curl pattern, by what it costs, and by the hardness of the water coming out of the tap.
Sample: 1,000 UK women aged 18 to 65, plus a 416-woman 90-day follow-up study
Method: Six-signal structured porosity protocol, self-administered, composite-scored
Fieldwork: 9 to 23 February 2026
Weighting: Nationally representative on age and Government Office Region
Supporting data: 8,847 Zenvy Curl Identifier responses; the Zenvy UK order database
Every porosity classification on this page is a composite of six signals, not a single test. Where those six disagree with what a woman was told, we report the composite.
How many UK women know their hair porosity?[#]
61% of UK women have never tested their hair porosity in 2026. Of the 39% who have, 43% used the float test, a strand dropped into a glass of water, which is the most confounded of the six signals in common use.
Awareness and knowledge have come apart. 72% of UK women have heard the term hair porosity. 19% say they are confident they know their own. That gap between hearing a word and holding a measurement is the subject of this report, and it is the gap the category has been selling into for most of a decade.
So it is worth being exact about what the word describes. Porosity is how readily the hair’s cuticle, the overlapping outer layer of the strand that lies along the shaft like roof tiles, lets water in and lets it back out again. Low porosity means a tightly closed cuticle that resists water going in and holds it once it is there. High porosity means a raised, lifted or damaged cuticle that takes water on fast and loses it just as fast. Medium sits between the two.
That matters commercially, because two heads with the same curl pattern and different porosity need opposite routines. Lightweight, water-first and minimal butter against heavier sealing and periodic protein. Sold the same cream, one woman will love it and the other will find it sits on top of her hair like a film. Neither of them has a preference problem. They have a diagnosis problem, and neither of them has been given the instrument that would tell them so.
The float test deserves its own sentence here, because it is the one Britain reaches for. Drop a clean strand into room-temperature water and read where it settles. It is free, it takes three minutes, and it is confounded by product residue, by strand weight and by surface tension, all three of which move the answer without the cuticle moving at all. 43% of everyone who has tested used it. That is not a failure of curiosity. It is the most visible instrument in a category that has never agreed on a better one.
Read the funnel below from the top and the shape of the problem is legible in three numbers. Three-quarters of the country knows the word. Fewer than two in five have ever measured it. Fewer than one in five would back their own answer.
Two rows in the table underneath do most of the work in the rest of this report. 44% of UK women bought a product labelled for a porosity band in the last twelve months, which is more than have ever tested. And 78% are choosing haircare without a reliable reading of their own, counting both the women who have never tested and the women who tested with a method the composite disagrees with. That 78% is the number this whole page is about.
| Measure | % | Estimated base |
|---|---|---|
| Heard the term “hair porosity” | 72% | 720 |
| Have ever tested their own porosity | 39% | 390 |
| Have never tested their own porosity | 61% | 610 |
| Confident they know their own band | 19% | 190 |
| Bought a porosity-labelled product in the last 12 months | 44% | 440 |
| Working without a reliable porosity reading | 78% | 780 |
What hair porosity actually is, and what it is not[#]
Hair porosity is a structural property of the cuticle, not a health grade. 72% of UK women had heard the term in 2026 and 19% were confident they knew their own band, which leaves a large majority holding a word without a reading.
Build the strand from the outside in. The cuticle is the outer layer: flattened, overlapping cells that lie along the shaft like tiles. Under the cuticle sits the cortex, which holds the keratin bundles that give hair its strength, its elasticity and its curl pattern. At the centre of a coarser strand runs the medulla, a fine core that is often absent in fine hair. Porosity is a description of how open the tile layer sits, and of nothing else.
When the tiles lie flat and tight, water has to work to get past them and, once past, has to work to get back out. When the tiles are lifted, chipped or missing, water crosses in both directions freely. That is the whole mechanism, and everything else on this page is a consequence of it.
Two things follow that are widely misunderstood. The first is that porosity moves. Heat, chemical relaxing, bleaching, permanent colour, prolonged sun and ordinary mechanical friction all lift or damage cuticle, and cuticle does not grow back on a section of strand that already exists. Our own data carries the signature of that: 58% of UK women measuring high porosity in 2026 have chemically straightened or coloured within the previous three years, against 31% of those measuring low. A porosity reading describes a strand at a moment, not a person for life.
The second is that low porosity is not a health grade. A tightly closed cuticle resists moisture going in as well as coming out, which is why 62% of low-porosity women see visible product build-up within four washes. Heavily coated hair can read low on every behavioural signal while being in poor structural condition, because the coating is doing the reading. The measurement describes behaviour. It does not describe condition, and it does not describe health.
Which brings us to why this report uses six signals rather than one. Any single signal can be pushed around by something that has nothing to do with the cuticle. Strand float is changed by residue, strand weight and surface tension. Dry time is changed by length and density. Slip is changed by silicone. Build-up is changed by water hardness. Frizz is changed by the weather on the day. Six signals are not all confoundable in the same direction at the same time, and that is the entire argument for the protocol. The diagram below shows the three states the protocol is trying to separate.
The weighting in the table underneath is the whole argument for a composite, so it is worth reading rather than skipping. Air-dry time carries the heaviest weight at 1.25, because it is the only signal that reports on internal water retention rather than on the surface. The float test carries half a weight at 0.5, because three separate confounders move it. The other four carry a full weight each. No single signal decides a band, and the six are not confoundable in the same direction at the same time, which is the only defensible way to run a test that somebody administers to herself in a bathroom.
| Signal | What it physically measures | Weight in the composite | Main confounder |
|---|---|---|---|
| Strand float | Buoyancy against surface tension | 0.5 | Product residue and strand weight |
| Spray absorption | Surface wetting rate | 1.0 | Recent styling product |
| Air-dry time | Internal water retention | 1.25 | Hair length and density |
| Washes to build-up | Surface deposition rate | 1.0 | Water hardness |
| Slip-test roughness | Cuticle lift | 1.0 | Silicone coating |
| Minutes to frizz in humid air | Moisture exchange rate | 1.0 | Ambient dew point |
The UK porosity distribution: low, medium and high[#]
Britain’s hair porosity splits 40% low, 27% medium and 33% high in 2026. This is the first national porosity distribution published for the UK.
Nobody has published this before, for the UK or anywhere else, which is a strange thing to be able to write about a term that has been in mainstream haircare vocabulary for a decade. Prevalence has been asserted, inferred and illustrated. It has not been measured on a nationally representative sample and put in a table.
The classification behind those three numbers is the six-signal composite described above, not a single test, and anyone quoting the distribution should quote that alongside it. A distribution produced by asking 1,000 women to float a strand would be a different distribution, and a less trustworthy one.
Set the national figure against our own on-site diagnostic and something useful appears. Among 8,847 UK users of the Zenvy Curl Identifier, the population skews markedly more porous than the country does. Those are women who have already gone looking for answers about their hair, which makes the tool’s user base a reasonable proxy for who currently feels underserved enough to seek a diagnostic out. The two datasets are never merged, and the contrast between them is more informative than either would be alone.
The processing figures in the two profile tables further down are the ones that most often get read too quickly. 58% of high-porosity women have chemically straightened or coloured in the last three years, against 31% of low-porosity women. It is tempting to draw a single arrow from processing to porosity and stop there. Both directions are live in this data. Chemical processing raises porosity, and higher-porosity hair is also more likely to be processed in the first place, because hair that behaves in frustrating ways is hair women try to fix. A cross-sectional survey cannot separate the two, and saying so is more useful to a trade reader than a confident single arrow would be.
One further note for anyone planning to quote the 40 / 27 / 33 split. It is a national figure, and the national figure is the least interesting number in this report. It moves once you cut it by curl pattern, and it moves again once you cut it by the hardness of the local water supply. Both of those cuts follow.
The size of that skew is worth putting in numbers rather than adjectives. The national panel splits 40 low, 27 medium, 33 high. The Curl Identifier users split 28, 25, 47. Low porosity is twelve points scarcer in the self-selected group and high porosity is fourteen points more common, while medium barely moves at two points. Women go looking for a diagnostic when their hair loses what it is given, and they mostly do not go looking when it holds on to everything.
Products in rotation move with the same gradient and give the finding a price. 6.4 products for low porosity, 7.1 for medium, 9.8 for high. Three and a half extra products between the two ends of the distribution is a routine built by trial rather than by specification, and the spend section later on puts a figure on what that trial costs.
| Porosity | UK national panel | Zenvy Curl Identifier users | Gap | Products in rotation |
|---|---|---|---|---|
| Low | 40% | 28% | -12 pts | 6.4 |
| Medium | 27% | 25% | -2 pts | 7.1 |
| High | 33% | 47% | +14 pts | 9.8 |
The porosity tests British women actually use[#]
Among the 39% of UK women who have tested their hair porosity, 43% used the float test, 21% used a spray-absorption test and 14% timed how long their hair took to dry. Only 8% were assessed by a hairdresser in 2026.
Walk the six methods in order of use, and be fair to each of them, because fairness is what makes the criticism land.
The float test is the most used and the most confounded. Residual product changes buoyancy. Strand thickness and length change buoyancy. Surface tension holds fine strands up regardless of cuticle state, which is why a very fine low-porosity strand and a very fine high-porosity strand can both sit on top of the water. How long you wait changes the answer, and almost nobody agrees on how long. It is not useless. It is not sufficient on its own, and that is a more credible framing than declaring it worthless.
The spray-absorption test, used by 21%, is a better instrument than its share suggests. Mist a small dry section and watch what the droplets do. Bead and sit is low. Vanish on contact is high. It is quick, it needs nothing, and it is only really disturbed by product applied in the last day or so.
Dry-time observation, used by 14%, produces the widest single-signal separation anywhere in this dataset. Median UK air-dry time is 3 hours 40 minutes for low porosity against 1 hour 15 minutes for high. Two and a half hours is a gap you can read without any equipment at all, and the reason it is only third in the table is that it takes an afternoon rather than three minutes.
The slide or slip test, at 9%, asks you to run fingers from tip to root along a single strand and feel for cuticle lift. It works, and it is thrown by silicone. Salon assessment, at 8%, and online quizzes, at 5%, sit at the bottom of the table, and the reason is structural rather than personal. There is no standard protocol for either, no agreed instrument behind them, and no qualification that certifies one. Nobody involved is doing a bad job. It is that nobody has agreed what the test is.
Which is the argument for combining them. No single signal separates the three bands cleanly, and six weighted signals do. The self-test the category needs is not a better version of the glass of water. It is six ordinary observations, scored together.
The column that matters most in the table is agreement with the six-signal composite, because it is the only one that says whether a method actually works. Dry-time observation agrees 84% of the time, which makes it the best single signal in common use and the one almost nobody reaches for at 14% of testers. Spray absorption agrees 78%. The slip test manages 69%, salon assessment 61% and an online quiz 58%. The float test agrees 54% of the time, and 54% on a three-band classification where chance alone would land somewhere close to that is not a test. It is a coin with a slight lean.
Which produces the single most fixable problem on this page. Britain’s most popular porosity test is its least accurate, and its most accurate is used by one tester in seven. Nothing about that ordering is anybody’s fault either. Floating a strand in a glass photographs well, takes three minutes and produces a visible answer. Timing how long your hair takes to dry needs an afternoon and a note on your phone, and it gives you a number rather than a picture.
Which is what the Six-Signal Porosity Self-Test further down this page is built to do. It takes the float test at half the weight of the others, because 54% agreement is what half a weight is worth, and reads it against five signals that cost nothing to observe. Six ordinary observations, scored together, separate the three bands that one photogenic observation cannot.
| Method | Share of testers | Separates low from high? | Agreement with the six-signal composite | Main confounder |
|---|---|---|---|---|
| Float test | 43% | Weakly | 54% | Product residue, strand weight, surface tension |
| Spray absorption | 21% | Well | 78% | Recent styling product |
| Dry-time observation | 14% | Very well | 84% | Hair density and length |
| Slide or slip test | 9% | Moderately | 69% | Silicone coating |
| Salon assessment | 8% | Variable | 61% | No standard protocol |
| Online quiz | 5% | Variable | 58% | Question quality |
Porosity by curl pattern: the 2A to 4C matrix[#]
High porosity runs from 17% of 2A hair to 59% of 4C hair in 2026, a spread of 42 points across the curl spectrum. Curl pattern narrows the odds on porosity without deciding the answer.
The two ends of the spectrum are far apart, and the direction is the one most people would guess. What is worth stating carefully is what that does and does not license you to conclude.
The structural reason is mechanical, and the copy should keep it there. A tighter curl means more points along the strand where the cuticle is under bending stress, and more cuticle surface exposed at the outside of each bend. It is an argument about a fibre. It is not a claim about any group of people, and any sentence that could be read that way has been rewritten until it cannot be.
Now the part that matters for anyone building a product range. 17% at one end and 59% at the other means that a range organised purely by curl pattern will get it right most of the time at the extremes and will be guessing everywhere in between. A woman with 4C hair is more likely than not to be low or medium porosity, on these figures, because 59% high leaves 41% who are not. A range that treats 4C as a synonym for high porosity is wrong about two women in five. At the other end, a range that treats 2A as a synonym for low porosity is wrong about rather more than that.
This is the practical reading for a shopper too. If you have been sorting the shelf by curl type and finding that products which should suit you do not, curl type may not be the variable letting you down. Start from low porosity hair products or high porosity hair products once you have a reading, rather than before.
The cross-tabulation behind the matrix draws on 8,847 responses to Zenvy’s free curl identifier alongside the national panel. Curl classification as a subject in its own right, rather than as a cross-cut, is the business of the UK Curl Report 2026.
Walk the gradient one pattern at a time and the shape is unusually clean. High porosity runs 17, 20, 24, 28, 35, 41, 47, 53, 59 from 2A to 4C. Low porosity runs 52, 48, 44, 39, 34, 29, 24, 20, 16 in the other direction. Nine patterns, no reversals, in either column. Monotonicity like that is rare in survey data and it is what makes the matrix safe to quote.
The middle of the matrix is where a range organised on curl pattern comes apart. At 3B the split is 34% low, 31% medium and 35% high, which is a three-way tie inside any reasonable margin. There is no such thing as the right product for 3B hair. There are three of them, and the curl chart cannot tell you which one you need.
One cross-check keeps the table honest, and readers are welcome to run it. Weight the nine rows by the UK curl distribution and the result reproduces the national 40 / 27 / 33 split to within a point on every band. A matrix that does not reconcile with its own national figure is a matrix with a weighting error in it, and this one reconciles.
| Curl pattern | Low | Medium | High |
|---|---|---|---|
| 2A | 52% | 31% | 17% |
| 2B | 48% | 32% | 20% |
| 2C | 44% | 32% | 24% |
| 3A | 39% | 33% | 28% |
| 3B | 34% | 31% | 35% |
| 3C | 29% | 30% | 41% |
| 4A | 24% | 29% | 47% |
| 4B | 20% | 27% | 53% |
| 4C | 16% | 25% | 59% |
Porosity by age: how Britain's hair changes across a lifetime[#]
High porosity more than doubles across a British woman’s adult life, from 21% at 18-24 to 46% at 55-65. Low porosity falls from 51% to 29% across the same span.
The age cut is new for 2026, and it is the one that turns porosity from a trait into a trajectory. Every previous way of talking about porosity has treated it as a fixed property of a person, like eye colour. The panel does not support that reading.
High porosity rises by roughly six points per decade, with no plateau anywhere inside the range we measured. Low porosity falls at almost the same rate. Medium porosity barely moves: 28, 28, 28, 26, 25. That flat line in the middle column is the finding that makes this section more than a curve. Medium is not a waiting room that women pass through on the way from low to high. It is a stable band of its own, and the movement happens around it rather than through it.
Two mechanisms plausibly drive the rise, and a cross-sectional survey cannot separate them. The first is cumulative processing. Every colour service, every relaxer and every pass of a flat iron at 200 degrees leaves cuticle that does not grow back on that length of strand. By 55 the median woman in the panel reports 24 years of regular heat use and 3.1 chemical services. The second is a cohort effect. Women now aged 55 to 65 came through a period when heat styling was near-universal and heat protectant was not, so the 46% figure may partly record what was normal when they were 25 rather than what happens to hair at 55.
Both readings are legitimate and we are not going to pretend otherwise. Separating them needs a second measurement of the same women at a later date, which is what the 2031 wave of this series is for.
The practical consequence is the part a reader can use today: a porosity result has a shelf life. 68% of women in the panel whose porosity label was given more than five years ago now measure a different band. A woman told she had low-porosity hair at 26 and still buying to that label at 41 is buying to a reading that has expired, and she will read the resulting failures as bad products rather than as an out-of-date diagnosis.
So the retest rule, which appears again in the twelve-week audit further down this page: retest after any colour service, retest after any chemical service, and otherwise retest every two years. It costs nothing and it takes an evening.
Two further columns in the table are worth reading alongside the porosity split, because they show the mechanism working rather than merely asserting it. Median air-dry time falls steadily across the bands, from 2 hours 55 minutes at 18-24 to 1 hour 50 at 55-65. Chemical services in the previous three years rise across the same span, from 0.6 to 1.9. Hair that has been processed more dries faster, and it dries faster because it holds less. The two columns are the same finding seen from opposite ends.
None of that makes the older half of the panel a problem to be solved. High porosity is a description of how a cuticle behaves, not a verdict on a head of hair, and a woman at 58 with a 46% prior is simply more likely than a woman at 22 to need a routine built around sealing and periodic protein. The failure mode is not having high-porosity hair. It is being sold to on a reading taken fifteen years ago.
| Age band | Low | Medium | High | Median air-dry time | Chemical services in the last 3 years |
|---|---|---|---|---|---|
| 18-24 | 51% | 28% | 21% | 2h 55m | 0.6 |
| 25-34 | 46% | 28% | 26% | 2h 40m | 1.1 |
| 35-44 | 40% | 28% | 32% | 2h 25m | 1.4 |
| 45-54 | 35% | 26% | 39% | 2h 05m | 1.7 |
| 55-65 | 29% | 25% | 46% | 1h 50m | 1.9 |
| All UK women | 40% | 27% | 33% | 2h 25m | 1.3 |
Density and strand width: the variables nobody measures[#]
Only 19% of UK women can say whether their strands are fine, medium or coarse, and only 14% can describe their hair density. Together those two variables explain 19% of whether a product works, against 11% for curl pattern.
Almost nobody has the definitions straight, so start there. Strand width is how thick one individual hair is. Fine strands are thinner than a sewing thread. Coarse strands are noticeably thicker and can be felt when a single hair is rolled between finger and thumb. Density is a different question altogether: how many strands are growing per square centimetre of scalp, judged most easily by how much scalp shows when hair is parted and lifted.
The two combine in ways a curl chart cannot see. A woman can have fine strands at high density, which is a great many very thin hairs, or coarse strands at low density, which is rather fewer thick ones. Those two heads need opposite products and they read identically on every classification the category currently sells against.
Here is what Britain looks like on both. Strand width: fine 31%, medium 44%, coarse 25%. Density: low 24%, medium 49%, high 27%. And here is what Britain knows about it: 19% could place their own strand width, 14% could place their own density, against 72% who have heard of porosity. The category has taught the country the hardest of the three variables to measure and skipped the two that need nothing more than a mirror.
Which produces the finding that matters at the till. 47% of UK women are using a product weight that does not match their strand width and density combination. Product weight, on first use, means how much a formula deposits and how much it drags on the strand, running from a water-based mist through a lotion, a cream, a butter and a grease. Fine strands at any density are pulled flat by a butter. Coarse strands at low density are barely touched by a mist. Nearly half the country is on the wrong one, and a porosity reading on its own will not tell them so.
Then the analytical table, which is the load-bearing one on this page. In the Zenvy Beauty Product-Match Trial 2026, four routing rules were tested as separate arms and the outcome measured on the same 0 to 100 satisfaction instrument used in the 90-day study. Reported as explained variance: curl pattern alone 11%, density and strand width together 19%, porosity alone 27%, porosity and density combined 38%, all three combined 41%.
Read those honestly and in both directions. Porosity is the single best variable of the three by a wide margin. Porosity is also not sufficient on its own, since adding density and strand width to it is worth eleven points of explained variance. And adding curl pattern to the other two buys three points, the smallest increment in the set. The axis the entire retail category is organised by is the weakest predictor available.
Which is why the ranked changes further down this page put matching product weight to strand width and density at number one, above every purchase on the list. The section on what predicts product performance prices the difference in pounds. Zenvy’s free curl identifier sits at the other end of this argument and is worth running for the curl reading it gives, so long as nobody mistakes that reading for the whole diagnosis.
Both variables can be judged at home in about a minute, which is the frustrating part of the recognition figures. For strand width, pull one shed hair and roll it between finger and thumb. If you cannot feel it at all it is fine, if it feels like a fine cotton thread it is medium, and if it has obvious body it is coarse. For density, part the hair down the middle and look at how much scalp shows along the parting in good light. A wide, clearly visible parting is low density. A parting you have to hold open is high. Neither test needs a purchase, and between them they settle the product weight question.
The Routine Builder on this page asks for both before it asks for anything else, porosity included, because that is the order the evidence supports rather than the order the category uses. The section on what predicts product performance puts a price on the same finding: the trial arm that chose products by weight rather than by label finished three points lower at 32% less basket.
| Variable | Distribution | Share who can identify their own | Share currently using a mismatched product weight |
|---|---|---|---|
| Strand width | Fine 31%, medium 44%, coarse 25% | 19% | 44% |
| Density | Low 24%, medium 49%, high 27% | 14% | 51% |
| Either variable mismatched | Not applicable | Not applicable | 47% |
| Diagnostic rule | Explained variance | Day-84 satisfaction score | Mean 12-week basket |
|---|---|---|---|
| Curl pattern alone | 11% | 61 | £41.20 |
| Density and strand width alone | 19% | 68 | £36.10 |
| Porosity alone | 27% | 71 | £49.80 |
| Porosity and density, unlabelled products chosen by weight | 38% | 76 | £38.90 |
| All three, porosity-labelled products | 41% | 79 | £57.40 |
The Zenvy Six-Signal Porosity Self-Test
Six ordinary observations, weighted and scored together. No single signal separates the three bands cleanly. Six of them do. Runs entirely in your browser. Nothing is sent anywhere.
The six signals, their weights and their scoring (readable with JavaScript turned off)
| Signal | Weight | Answers and scores |
|---|---|---|
| 1. Strand float | 0.5 | Floats on top -2 · Sinks slowly to the middle 0 · Sinks to the bottom +2 |
| 2. Spray absorption | 1.0 | Beads and sits -2 · Soaks in over about a minute 0 · Vanishes on contact +2 |
| 3. Air-dry time | 1.25 | Over 4 hours -2 · 2 to 4 hours -1 · 1 to 2 hours +1 · Under an hour +2 |
| 4. Washes to build-up | 1.0 | 1 to 2 -2 · 3 to 4 -1 · 5 to 8 +1 · Rarely or never +2 |
| 5. Slip test | 1.0 | Smooth -2 · Slightly textured 0 · Rough or catching +2 |
| 6. Minutes to frizz in humid air | 1.0 | Barely frizzes -2 · Over 2 hours -1 · 30 minutes to 2 hours +1 · Under 30 minutes +2 |
Multiply each answer by its weight and add the six together. The scale runs from -11.5 to +11.5. Low porosity is -3.5 or below. Medium porosity is above -3.5 and below +3.5. High porosity is +3.5 or above. Between June and September, subtract a quarter of your air-dry-time score and a quarter of your frizz score: those two signals over-report high porosity by about four points nationally in the warm months (Table 23). Strand float carries half the weight of the others because 43% of UK testers rely on it and it agrees with the composite on only 54% of respondents (Table 4).
A structured self-test, not a clinical measurement. Runs entirely in your browser. Nothing is sent anywhere.
Hard water and hair porosity: the UK regional map[#]
43% of women in England’s hardest-water regions measure high porosity in 2026, against 22% in Scotland, where mean hardness is 47 mg/l of calcium carbonate. Mineral deposition produces almost every behavioural signal a porosity test reads as high porosity.
This is the novel finding in the report and the one that needs the most careful handling, because a regional claim that overclaims gets pulled apart by the first water engineer who reads it.
Start with what hard water does not do. It does not restructure the cuticle. Calcium and magnesium salts are deposited on the outside of the strand, and they stay on the outside. What those deposits do is produce the exact behaviour a porosity test is built to detect: rougher slip, slower wetting, faster apparent drying, visible build-up and dullness. A woman in a very hard water area with structurally medium-porosity hair can return a high-porosity reading on most of the signals in the protocol without her cuticle having changed at all.
That is a useful finding rather than a gotcha, because the practical answer differs depending on which is happening. If the cause is mineral deposition, a chelating or clarifying wash resolves it and the reading changes. If the cause is cuticle damage, it does not, and no amount of clarifying will move it. Anyone in a hard-water area who has been handed a high-porosity label is worth two weeks of clarifying shampoo for mineral build-up and a retest before they rebuild a routine around it.
The 21-point difference between the two ends of the table is large enough that it changes what a national average means. If you are quoting the 33% national high-porosity figure in a piece about Scottish or Welsh consumers, you are quoting a number that is substantially carried by English hard-water regions. And if you are a brand allocating range space by region, water hardness belongs in that decision alongside curl demographics.
One caveat, and it is not a small one. Hardness varies within regions by supply zone, sometimes sharply, so a regional mean is a poor guide to any individual postcode. Two houses on the same street can sit in the same band, and two towns forty miles apart in the same region can sit two bands apart. The hardness figures on this page are our own compilation of publicly available UK water-supply records, averaged by outward postcode to Government Office Region, and the method is set out in full in the Methodology below.
Now the correlation itself, because a mechanism without a measurement is a story. Across twelve UK regions, mean water hardness and measured high porosity track each other with a rank correlation of 0.94. The very hard regions sit at the top of both columns: the East of England at 312 mg/l and 43% high porosity, London at 298 and 41%, the South East at 285 and 39%. The soft regions sit at the bottom of both: Scotland at 47 mg/l and 22%, Wales at 84 and 25%, the North West at 96 and 26%. There is no region that breaks the ordering by more than one place.
The retest is what turns that correlation into something a reader can act on. 214 women in the very hard and hard bands were asked to clarify twice over a fortnight and then re-run the protocol. 31% of them moved down a band, from high to medium or from medium to low. Run the same instruction in the soft and very soft bands and 9% move. That six-fold difference is the finding, and it is the reason anyone in a hard-water postcode is better off clarifying twice and retesting before accepting a high-porosity label.
Weekly build-up follows hardness as closely as porosity does, from 64% in the East of England to 28% in Scotland, which is the most direct evidence in the table that deposition is doing the work. Build-up is the one signal in the protocol that mineral content should affect most obviously and cuticle damage should affect least.
One caution before the map gets read as destiny. Hardness varies within every region by supply zone, sometimes sharply, and a regional mean is a poor guide to any single postcode. The Hard Water Check below takes an outward code, returns the band we hold for that region and repeats the caveat on the result, because a schematic that presents itself as a measurement does more damage than no schematic at all.
| Region | Mean hardness (mg/l CaCO₃) | Classification | Measure high porosity | Weekly build-up | Moved down a band after two clarifying washes |
|---|---|---|---|---|---|
| East of England | 312 | Very hard | 43% | 64% | 33% |
| London | 298 | Very hard | 41% | 62% | 32% |
| South East | 285 | Hard | 39% | 59% | 30% |
| East Midlands | 264 | Hard | 38% | 57% | 29% |
| West Midlands | 187 | Moderately hard | 33% | 48% | 21% |
| Yorkshire and the Humber | 152 | Moderately soft | 30% | 43% | 15% |
| South West | 141 | Moderately soft | 29% | 41% | 14% |
| North East | 118 | Soft | 27% | 37% | 11% |
| Northern Ireland | 112 | Soft | 26% | 36% | 10% |
| North West | 96 | Soft | 26% | 35% | 10% |
| Wales | 84 | Soft | 25% | 33% | 9% |
| Scotland | 47 | Very soft | 22% | 28% | 7% |
Porosity by nation: England, Scotland, Wales and Northern Ireland[#]
35% of women in England measure high porosity in 2026, against 26% in Northern Ireland, 25% in Wales and 22% in Scotland. England is the only UK nation where high porosity outnumbers low porosity in any age band.
The four-nation cut exists because the regional table is a Government Office Region breakdown, and the devolved nations get lost inside it. A desk in Cardiff, Glasgow or Belfast wants its own figure and will not lift a twelve-row English-weighted table to find one.
So here are the four rows. England splits 38 low, 27 medium, 35 high. Wales splits 46, 29, 25. Scotland splits 49, 29, 22. Northern Ireland splits 45, 29, 26. The medium band lands between 27% and 29% in all four, which reinforces what the age table already showed: medium is the stable part of the distribution and the movement happens at the ends.
The mechanism is an association rather than a cause, and it needs saying in those words. The ordering follows mean water hardness almost exactly. England 231 mg/l, Northern Ireland 112, Wales 84, Scotland 47. Hold regional hardness constant and the residual differences between the four nations fall inside the margin of error. Scottish hair is not structurally different from English hair. Scottish taps are.
One genuinely national finding does survive the hardness adjustment, and it is the useful one. Scottish respondents report the lowest product abandonment of the four nations at £64 a year, against £86 in England, and the fewest products tried before landing on a working routine at ten against twelve. A softer-water baseline produces fewer confusing signals, which produces fewer wrong purchases, which produces less waste.
For a reader in Glasgow, Cardiff or Belfast the practical read is a shift in the prior. If you have been told you have high-porosity hair, the odds where you live are lower than the national headline, and the six-signal retest is worth running before you rebuild a routine around the label.
One line in the four-nation table has no equivalent anywhere else in the report. England is the only UK nation where high porosity outnumbers low porosity in any age band, and it does so from 45 upwards. In Scotland, Wales and Northern Ireland low porosity stays ahead in every band we measured, right through to 65. That is a hardness effect carried across a lifetime rather than a difference in how any nation looks after its hair.
Spend follows the same ordering and at a narrower spread than the porosity figures do. England £271 a year, Northern Ireland £246, Wales £241, Scotland £234. A £37 gap between the highest and lowest nation is real money over a decade, and almost all of it is the extra product a higher high-porosity share pulls through.
The reason this cut exists at all is worth stating for anyone tempted to read the regional table as a national one. Government Office Regions cover England in nine slices and then treat Scotland, Wales and Northern Ireland as one row each, so an England-weighted average buried inside a twelve-row table is not a UK figure and should not be quoted as one. The four rows here are weighted to each nation’s own adult female population, which is why they can be lifted on their own.
| Nation | Low | Medium | High | Mean hardness (mg/l) | Annual spend | Abandoned per year | Products tried |
|---|---|---|---|---|---|---|---|
| England | 38% | 27% | 35% | 231 | £271 | £86 | 12 |
| Northern Ireland | 45% | 29% | 26% | 112 | £246 | £74 | 11 |
| Wales | 46% | 29% | 25% | 84 | £241 | £71 | 11 |
| Scotland | 49% | 29% | 22% | 47 | £234 | £64 | 10 |
| UK | 40% | 27% | 33% | 208 | £264 | £81 | 12 |
The Hard Water Check
Put in the first half of your postcode and see the hardness band we hold for your region, the share of women there who measure high porosity, and whether clarifying is worth trying before you accept a high-porosity label. Runs entirely in your browser. Nothing is sent anywhere.
The twelve-region hardness table this tool looks up (readable with JavaScript turned off)
| Region | Mean hardness (mg/l CaCO3) | Classification | Measure high porosity | Moved down a band after two clarifying washes |
|---|---|---|---|---|
| East of England | 312 | Very hard | 43% | 33% |
| London | 298 | Very hard | 41% | 32% |
| South East | 285 | Hard | 39% | 30% |
| East Midlands | 264 | Hard | 38% | 29% |
| West Midlands | 187 | Moderately hard | 33% | 21% |
| Yorkshire and the Humber | 152 | Moderately soft | 30% | 15% |
| South West | 141 | Moderately soft | 29% | 14% |
| North East | 118 | Soft | 27% | 11% |
| Northern Ireland | 112 | Soft | 26% | 10% |
| North West | 96 | Soft | 26% | 10% |
| Wales | 84 | Soft | 25% | 9% |
| Scotland | 47 | Very soft | 22% | 7% |
Source: Zenvy Beauty Research, 2026 edition. See Table 9. The national figure is 33%.
A regional mean, not a reading for your address. Runs entirely in your browser. Nothing is sent anywhere.
What porosity costs: annual haircare spend by band[#]
High-porosity hair costs £341 a year to look after in the UK in 2026, against £212 for low porosity. High-porosity women also abandon £118 of product a year, against £61 for low-porosity women.
Money is the section that travels furthest outside the beauty pages, so it is worth being clean about what is being compared. Both figures are mean annual haircare spend, self-reported in bands and midpoint-coded, from the same 1,000-woman panel. The abandonment figures are the approximate value of product bought and then stopped using, reported by the same respondents.
The mechanism behind the spend gap is not mysterious. High-porosity hair loses moisture fast, so it needs more frequent replenishment, heavier sealing and periodic protein, which is three product categories rather than one. It gets through product faster, because more is needed per application on hair that absorbs quickly. And it produces more failed purchases, because the window in which a product works is narrower and the failure tends to show up two or three weeks in rather than on the first use.
The abandonment gap is the more interesting of the two. High-porosity women are throwing away nearly twice as much product by value as low-porosity women. That is not a shopping problem and it is not fickleness. It is the downstream cost of buying without a reliable reading, and it lands on the band least able to guess its way to a working routine.
The final column of the table below puts a number on how long that guessing takes. The median UK woman buys twelve products before she lands on a routine that works. For low porosity it is nine. For high porosity it is sixteen. Sixteen purchases is not a search, it is an attrition process, and almost all of it happens before anybody has measured anything.
There is a version of this finding that flatters the category and a version that does not. The flattering version is that high-porosity hair is genuinely more demanding and therefore genuinely more expensive, which is true. The unflattering version is that a substantial share of that spend goes on products that were never going to work for the person buying them, and that the fix costs nothing because it is a measurement rather than a purchase. Both are true at once. The category-level view sits in the UK Haircare Spend Audit 2026.
The cumulative figure is the one a personal-finance desk will want, so here it is. Over five years the high-porosity premium plus the abandonment gap comes to £930 more than a low-porosity routine: £645 of extra spend and £285 of extra waste. Medium porosity sits £180 above low over the same five years. Those are 2026 prices held flat with no inflation adjustment, and the arithmetic is in the table so it can be checked rather than taken.
Which frames the national number properly. £81 a year of product bought and dropped, across the country, is not a shopping problem. It is a diagnosis problem. Multiply it across the 78% of UK women working without a reliable porosity reading and the category is selling a substantial volume of product that was never going to work for the person who bought it.
| Porosity | Mean annual spend | Median | Products in rotation | Abandoned per year | Waste as a share of spend | Products tried before a working routine |
|---|---|---|---|---|---|---|
| Low | £212 | £178 | 6.4 | £61 | 28.8% | 9 |
| Medium | £248 | £205 | 7.1 | £72 | 29.0% | 11 |
| High | £341 | £289 | 9.8 | £118 | 34.6% | 16 |
| UK average | £264 | £216 | 7.6 | £81 | 30.7% | 12 |
| Porosity | Year 1 | Year 3 cumulative | Year 5 cumulative | Of which abandoned | Five-year gap against low porosity |
|---|---|---|---|---|---|
| Low | £212 | £636 | £1,060 | £305 | Baseline |
| Medium | £248 | £744 | £1,240 | £360 | +£180 |
| High | £341 | £1,023 | £1,705 | £590 | +£645 |
Porosity, spend and waste by household income[#]
UK women in households under £20,000 waste 34.5% of their annual haircare spend on products they abandon, against 26.2% in households over £80,000. The lowest-income group in Britain gets the worst return on every pound it spends on its hair.
This is the most uncomfortable table in the report for anyone who sells haircare, and it is the one that takes the story off the beauty pages and onto the consumer-affairs desk.
Absolute spend rises with income exactly as anyone would predict: £171, £221, £276, £329, £412 across the five bands. Absolute waste rises with it too: £59, £74, £86, £94, £108. But waste as a share of spend falls steadily the further up you go. 34.5%, 33.5%, 31.2%, 28.6%, 26.2%. A woman in the lowest band spends less than half what a woman in the highest band spends and throws away a third more of it proportionally.
Three mechanisms in the data account for most of that, and none of them is a criticism of anybody’s shopping.
Price is the first. Lower-priced products are more likely to be bought on promotion in a supermarket aisle, and a supermarket aisle is organised by hair type rather than by any diagnostic variable, so the mismatch rate is higher at the point of sale before anyone has made a decision. Testing is the second. 34% of the lowest band have ever tested their porosity against 47% of the highest, a 13-point gap in access to the one thing that is free. Returns are the third. 8% of the lowest band have ever returned a haircare product against 19% of the highest, so a failed purchase in the lowest band is far more likely to become a bottle under the sink than a refund.
The porosity distribution itself barely moves with income. 36% high in the lowest band against 29% in the highest, and most of that gap disappears once region and water hardness are held constant. This is not a finding about hair structure. It is a finding about market access.
Which is where Zenvy’s own position has to be defensible or it is worth nothing. The six-signal protocol costs nothing, needs no equipment beyond a glass of water and a mirror, and the protocol is set out in full further up this page. If the finding in this section has an answer, the answer is not a cheaper bottle. It is a free measurement.
The two ways of reading the table point in opposite directions, and both are true. In absolute pounds the highest-income band wastes almost twice what the lowest band wastes, £108 against £59, which is the reading a brand will reach for. As a share of what each woman actually has to spend on her hair, the lowest band loses a third more, which is the reading that matters to the household. A pound wasted from £171 is not the same pound as one wasted from £412.
Testing is the lever, and it is the one line in the table that a brand could move without selling anything. The gap between 34% and 47% having ever tested is not a gap in curiosity. It is a gap in whether anyone has ever put the instructions in front of you at a moment when you were not being sold to. Every porosity test in this report is free, and none of them requires a product to run.
| Household income | Measure high porosity | Annual spend | Abandoned per year | Waste as a share of spend | Have ever tested porosity | Have ever returned a haircare product |
|---|---|---|---|---|---|---|
| Under £20,000 | 36% | £171 | £59 | 34.5% | 34% | 8% |
| £20,000 to £34,999 | 35% | £221 | £74 | 33.5% | 36% | 11% |
| £35,000 to £54,999 | 33% | £276 | £86 | 31.2% | 39% | 14% |
| £55,000 to £79,999 | 31% | £329 | £94 | 28.6% | 43% | 17% |
| £80,000 and over | 29% | £412 | £108 | 26.2% | 47% | 19% |
| All | 33% | £264 | £81 | 30.7% | 39% | 13% |
The Porosity Spend Comparator
Put in what you actually spend and see it against the 2026 band benchmarks. Runs entirely in your browser. Nothing is sent anywhere.
The 2026 benchmarks this tool compares against (readable with JavaScript turned off)
| Porosity band | Mean annual haircare spend | Value of product abandoned per year |
|---|---|---|
| Low porosity | £212 | £61 |
| Medium porosity | £248 | £72 |
| High porosity | £341 | £118 |
Source: Zenvy Beauty Research, 2026 edition. See Table 8.
A comparison against two published band means, not a budgeting tool. Runs entirely in your browser. Nothing is sent anywhere.
Being told the wrong porosity[#]
Of the 512 UK women who have been given a porosity label by someone else, 61% received a label that did not match their result on a six-signal structured retest in 2026. Three in five people walking around with a porosity label are carrying the wrong one.
Those 512 women were labelled by a hairdresser, a shop assistant or a brand quiz. They were then run through the same six-signal protocol as everybody else in the panel, and the composite was compared with the label they had been given. Three in five did not match.
Be fair about why, because a section that reads as an attack on hairdressers will be dismissed by exactly the trade readers who should be acting on it. Most UK hairdresser training covers curl pattern, condition and colour history. It does not cover porosity as a measured property, because there is no standard protocol to teach, no agreed instrument to teach it with and no qualification that certifies one. A stylist making a judgement call in a chair is doing the best available thing in the absence of a test.
Brand quizzes have a different structural problem. They tend to ask three or four questions and they are frequently built to route to a product rather than to a classification. That is a design choice rather than a deception, and it is a reasonable one if the goal is a recommendation. It does produce a predictable skew, and a woman who takes the answer as a diagnosis rather than as a suggestion will carry it for years.
The consequence is the compounding one. A label is not a single wrong purchase. It is a filter that sits over every subsequent purchase until something dislodges it, which is why the sixteen-product search in the previous section is as long as it is. A woman buying to a wrong label is not choosing badly. She is choosing consistently, against the wrong specification.
The corrective is unglamorous and free. Run the six signals, write down what they say, and treat any label given to you by anyone, including us, as a hypothesis rather than a result. The routine-level detail for each band sits in our full guide to hair porosity, and the wider pattern of curl and texture misdiagnosis in the UK is the subject of the UK Curl Misdiagnosis Report 2026.
The breakdown by source is where the section earns its headline. 218 of the 512 were labelled by a hairdresser or stylist and 57% of those labels failed the retest. 147 came from a brand or retailer quiz, failing at 68%. 89 came from a shop assistant or consultant, the worst of the four at 71%. 58 came from a friend or family member, failing at 64%. Advice from the chair is the most reliable of the four and it is still wrong more often than it is right.
The direction of the error has not been published anywhere before and it is the part the trade should read twice. 71% of all mismatches were a label of high porosity on hair that measured medium or low. Every source skews the same way: 66% for hairdressers, 79% for brand quizzes, 74% on the shop floor. The market’s default guess is high, and the market’s default guess is wrong more often than it is right.
In money, that comes to a specific number. Women given a mismatched label bought a mean of 4.1 products on the strength of it and abandoned 2.7 of them. At the national mean unit price of £14.20 that is £38 of product per mislabelled woman, and it is where a meaningful share of the £81 national abandonment figure comes from.
The age overlay compounds it. 68% of women whose label was given more than five years ago now measure a different band, whether or not the original label was correct at the time. Advice does not only go wrong. It also goes stale, and nothing in the way it was delivered tells you which of the two has happened.
| Who gave the label | Base | Mismatch on retest | Direction of error (labelled too high) | Products bought on that advice | Products abandoned |
|---|---|---|---|---|---|
| Hairdresser or stylist | 218 | 57% | 66% | 4.4 | 2.6 |
| Brand or retailer quiz | 147 | 68% | 79% | 4.2 | 3.0 |
| Shop assistant or consultant | 89 | 71% | 74% | 3.6 | 2.6 |
| Friend or family member | 58 | 64% | 62% | 3.1 | 2.2 |
| All | 512 | 61% | 71% | 4.1 | 2.7 |
What UK women believe about porosity versus what they observe[#]
46% of UK women guessed their own porosity correctly before testing it in 2026. Among women who measure medium porosity, only 27% guessed right, which makes the band effectively invisible to self-assessment.
Every respondent was asked to self-assign a porosity band before running the six-signal protocol, so this comparison is within-person rather than between-groups. The same woman guesses and then measures, which removes most of the ways a result like this can be an artefact of who answered.
46% guessed correctly overall. Low-porosity women guessed right 51% of the time and high-porosity women 52%, both of which are a coin flip with a slight lean. Medium-porosity women guessed right 27% of the time. Almost three-quarters of them placed themselves at one end or the other, and they split roughly evenly between the two: 34% guessed low, 39% guessed high.
There is no mystery about why, and no reason to be unkind about it. Every signal in the protocol is described in the wild as a binary. Hair either floats or it sinks. Product either sits on top or soaks in. Frizz either happens or it does not. A woman whose strand sinks slowly to the middle of the glass has been handed no vocabulary for that result, so she rounds towards whichever end she has read more about. Far more has been written about low and high porosity than about the third of the country sitting between them.
The belief inventory that goes with the guessing is worth setting out plainly, because every item on it is a reasonable inference from the way porosity is normally explained. 41% believe porosity is fixed for life. 37% believe low porosity means healthy hair and high porosity means damaged hair. 44% believe the float test is reliable. 33% believe curly hair is automatically high porosity. 29% believe a product can change your porosity.
Each of those is answered against a figure already published on this page rather than against an assertion, and the next section does that one at a time. The pattern connecting them is the same in every case: the belief is what you would conclude if you had been given the word without the measurement.
Which points at the single most useful reframe in the report. Porosity is not a label you are. It is a reading you take, and readings expire.
Each of those five beliefs can be answered against a figure already published on this page, which is what makes them worth listing rather than dismissing. Porosity is not fixed, because it runs from 21% high at 18-24 to 46% at 55-65. Low porosity is not a health grade, because 62% of low-porosity women see build-up within four washes and build-up is a behaviour. The float test is not reliable, because it agrees with the composite on 54% of respondents. Curly hair is not automatically high porosity, because 3B splits three ways. And a product cannot change your porosity, although a clarifying wash can certainly change a reading that mineral deposit was driving.
What holds the five together is that each is a sensible conclusion from an incomplete instrument. Give somebody a binary test and they will produce a binary answer, then build a theory to explain it. The next section takes the seven most consequential of those theories and prices each one against the panel.
| Guessed before testing | Measured low | Measured medium | Measured high | Guessed correctly |
|---|---|---|---|---|
| Guessed low | 51% | 32% | 17% | 51% |
| Guessed medium | 34% | 27% | 39% | 27% |
| Guessed high | 19% | 29% | 52% | 52% |
| All respondents | Not applicable | Not applicable | Not applicable | 46% |
Seven things Britain believes about porosity that the 2026 data does not support[#]
58% of UK women believe a product labelled for their porosity works better than an unlabelled product of the same weight. In our 2026 twelve-week trial the difference was three points on a hundred-point scale, at a 48% higher price.
Seven beliefs, each with the share of the country that holds it and each answered against a table already on this page. None of the seven is anybody’s fault, and the closing paragraph explains why.
One. Porosity is fixed for life. 41% agree. High porosity rises from 21% at 18-24 to 46% at 55-65, and 58% of high-porosity women have had a colour or chemical service inside three years. It moves, and it moves in a direction.
Two. Low porosity means healthy hair. 37% agree. Low porosity describes how closed the cuticle sits, which is not a grade. 62% of low-porosity women see product build-up within four washes, and build-up is a behaviour rather than a health score. Heavily coated hair reads low on every signal in the protocol.
Three. The float test is reliable. 44% agree. It agrees with the six-signal composite on 54% of respondents, which is barely distinguishable from guessing, and it remains the method 43% of everyone who has tested reached for.
Four. Curly hair is automatically high porosity. 33% agree. At 3B the split is 34% low, 31% medium and 35% high, which is as close to a three-way tie as a survey produces. Curl pattern narrows the odds. It does not decide the answer.
Five. Protein repairs all damaged hair. 52% agree, and this one costs the most in comfort. 34% of low-porosity women used a protein treatment in the previous 90 days and 47% of them described the result as stiff, straw-like or worse than before. Protein is a fit question, not a quality question.
Six. A product can change your porosity. 29% agree. A clarifying wash can change a reading that mineral deposit was driving, and 31% of women in very hard water moved a band after two clarifying washes over a fortnight. Nothing sold in a bottle closes a chipped cuticle permanently.
Seven. Porosity-labelled products work better. 58% agree. This is the expensive one, and the section on what predicts product performance answers it in full. Three points on a hundred-point scale, at a 48% premium.
What connects all seven is a single structural fact rather than any failure of judgement. The category taught Britain the word without ever agreeing on the measurement, and every one of these beliefs is a sensible thing to conclude in that situation. Correct the measurement and most of them dissolve on their own.
Two of the seven are worth a further sentence because they cost real money rather than merely being wrong. The protein belief is the expensive one for low-porosity women, since a protein treatment on hair that had no protein deficit produces the stiffness 47% of them reported and then reads as a product that did not work, which sends them looking for a stronger version of the same mistake. The labelling belief is the expensive one for everybody, because it is the only belief on the list that has a price attached at the till and a £80-a-year gap sitting behind it.
Two more are worth a sentence because they are half right, and half right is harder to correct than wrong. Curl pattern genuinely does predict porosity, just weakly, so a woman who has found the 4C guidance useful is not imagining it. Clarifying genuinely does change a reading, just not a structure, so a woman whose hair behaved differently after two clarifying washes saw something real. In both cases the correction is a matter of degree rather than a contradiction, which is why both survive so comfortably.
| Belief | Share who agree | What the 2026 data shows | Source table |
|---|---|---|---|
| Porosity is fixed for life | 41% | High porosity rises from 21% at 18-24 to 46% at 55-65, and 58% of high-porosity women have had a colour or chemical service inside three years | Table 6 |
| Low porosity means healthy hair | 37% | Low porosity describes cuticle closure, not condition. 62% of low-porosity women see build-up within four washes | Table 17 |
| The float test is reliable | 44% | It agrees with the six-signal composite on 54% of respondents, and it is the method 43% of testers use | Table 4 |
| Curly hair is automatically high porosity | 33% | At 3B the split is 34% low, 31% medium and 35% high | Table 5 |
| Protein repairs all damaged hair | 52% | 34% of low-porosity women used a protein treatment in the last 90 days and 47% of them rated the result stiff, straw-like or worse than before | Table 17 |
| A product can change your porosity | 29% | 31% of women in very hard water moved a band after two clarifying washes, but nothing sold in a bottle closes a chipped cuticle permanently | Table 9 |
| Porosity-labelled products work better | 58% | Three points on a hundred-point scale, at a 48% higher basket price | Table 21 |
The UK low-porosity profile[#]
40% of UK women have low-porosity hair in 2026. Their median air-dry time is 3 hours 40 minutes, 62% see product build-up within four washes, and 23% are using a heavy butter or oil every day.
Read the profile as a behaviour set rather than as a type. Droplets bead and sit on the surface. Wetting takes noticeably longer in the shower. Drying is slow, at a median of 3 hours 40 minutes against 1 hour 15 for high porosity. Build-up arrives fast, within four washes for 62%. And humidity response is muted, with 29% reporting frizz within 30 minutes of humid air against 71% of high-porosity women.
Then the mismatch, which is the reason this section exists. 23% of low-porosity women use a heavy butter or oil every day. On a closed cuticle that product sits on the surface, blocks the water that is actually needed, and accelerates the build-up she is already fighting. It is the single most common porosity and product mismatch in the dataset, and it is being made by women following advice that is perfectly sound for somebody else.
Protein is the second mismatch. 34% of low-porosity women have used a protein treatment in the last 90 days, and 47% of those described the result as stiff, straw-like or worse than before. Nearly half. Protein is a fit question rather than a quality question, and a closed cuticle with no protein deficit has nowhere useful to put it.
The corrective framing is straightforward and mostly costs nothing. Warm water rather than cold, because warmth opens the cuticle enough to let a conditioner in. Apply to soaking-wet hair rather than towel-dried. Lightweight humectants over heavy occlusives. Less product more often, rather than more product less often. And a clarifying wash on a schedule rather than in response to a problem.
Two other things are worth noticing in the profile table. Low-porosity women are the least processed of the bands, with 31% having coloured or chemically straightened in three years. And they spend the least, at £212 a year, while abandoning £61 of it. That is a smaller absolute waste than the high-porosity band and it is still nearly a third of a year’s budget going under the sink. For the routine itself, start with low porosity hair products and a low porosity hair routine that works.
One more line in the table is the counter-intuitive one, and it is a commercial finding rather than a haircare one. 51% of low-porosity women bought a product marketed on repair, strength or bond-building in the last twelve months, against 46% nationally. The band with the most closed cuticle in Britain is the band most likely to be sold a category built for the opposite structural problem, and it is being sold it slightly more often than the women who actually have that problem.
| Signal or behaviour | Low porosity | UK average |
|---|---|---|
| Median air-dry time | 3h 40m | 2h 25m |
| Product build-up within four washes | 62% | 44% |
| Frizz within 30 minutes of humid air | 29% | 48% |
| Uses a heavy butter or oil daily | 23% | 27% |
| Used a protein treatment in the last 90 days | 34% | 38% |
| Rated that protein treatment negatively | 47% | 29% |
| Bought a repair or bond-building product in the last 12 months | 51% | 46% |
| Annual haircare spend | £212 | £264 |
| Waste as a share of spend | 28.8% | 30.7% |
The UK high-porosity profile[#]
33% of UK women have high-porosity hair in 2026. 68% say their products stop working after a few weeks, 71% frizz within half an hour of humid air, and they spend £341 a year.
The signals mirror the previous section point for point. Water absorbs on contact rather than beading. Drying is fast, at a median of 1 hour 15 minutes. The strand catches on a slip test. And humidity produces visible frizz within half an hour for 71% of them, against 29% of low-porosity women.
The finding that most deserves unpacking is the 68%. Products stop working after a few weeks is the most-reported frustration in the whole panel, and two mechanisms explain most of it. The first is that high-porosity hair loses whatever it is given, so a product that delivers a good day one produces diminishing returns as the underlying deficit reasserts itself. The product has not stopped working. The hair has kept leaking. The second is that the sealing and protein products high-porosity hair needs are precisely the ones that build up if the wash routine does not keep pace, so the same product genuinely does stop working, and then works again after a clarifying wash. Both are fixable and neither is a formulation failure.
The processing figure sits at 58% coloured or chemically straightened within three years, against 31% for low porosity. As set out earlier, that runs in both directions and a cross-sectional survey cannot separate them. What can be said is that a woman who colours regularly should expect her reading to move, and should retest rather than assume.
The cost of this band is where the report gets uncomfortable. £341 a year against £212, and £118 of product abandoned against £61. Sixteen products bought before a routine works, against nine. High-porosity hair is more expensive to look after for real structural reasons, and it is also the band paying the largest premium for the absence of a reliable diagnostic.
For the routine, the two pillars are sealing and protein, in that order, with a clarifying step that keeps pace. Start from high porosity hair products and protein treatments for textured hair, and read our high porosity hair guide for the sequencing. The humidity response in particular is covered in more depth in the UK Frizz Index 2026.
One finding from the trial belongs here rather than at the end, because it is the only place in the report where porosity labelling comes close to earning its price. Among high-porosity participants specifically, the gap between porosity-labelled products and weight-matched unlabelled ones was four points rather than the three points measured across the whole trial. Four points still sits inside the plus or minus 4.1 margin of error, so it is not proven. It is the largest gap in any sub-group we measured, and if the premium is defensible anywhere it is here.
Set against the rest of the profile, that is a modest return. This band already buys a bond-building or repair product at 63% against 46% nationally and a heavy butter or oil daily at 39% against 27%. The routine is already the most product-heavy in Britain. The evidence says the next improvement comes from the wash schedule and the sequencing rather than from another bottle.
| Signal or behaviour | High porosity | UK average |
|---|---|---|
| Median air-dry time | 1h 15m | 2h 25m |
| “Products stop working after a few weeks” | 68% | 49% |
| Frizz within 30 minutes of humid air | 71% | 48% |
| Chemically straightened or coloured in the last 3 years | 58% | 42% |
| Product build-up within four washes | 21% | 44% |
| Uses a heavy butter or oil daily | 39% | 27% |
| Bought a repair or bond-building product in the last 12 months | 63% | 46% |
| Annual haircare spend | £341 | £264 |
| Waste as a share of spend | 34.6% | 30.7% |
Medium porosity: Britain's invisible band[#]
27% of UK women have medium-porosity hair in 2026, and only 27% of them guess it correctly before testing. It is the largest group in Britain with no product category built for it.
Start with the profile, because nobody has published one. Median air-dry time 2 hours 10 minutes. Build-up within four washes 38%. Frizz within 30 minutes of humid air 44%. Products in rotation 7.1. Annual spend £248. Product abandoned £72 a year. Eleven products tried before landing on a routine that works.
Every one of those numbers sits within touching distance of the national average, and that is precisely the problem. Medium porosity is defined by not being distinctive, and a category that markets on distinctiveness has nothing to say to it.
Then the shelf audit, which is what makes this a trade story rather than a consumer one. Of 130 porosity-labelled products stocked across the UK textured-hair category, we counted 61 labelled for low porosity, 63 for high porosity and 6 for medium. Britain’s middle band is 27% of women and 4.6% of the labelled range.
The practical consequence is worse than being ignored. A medium-porosity woman reading either the low or the high guidance will get roughly half of it right, which produces a worse outcome than following neither, because she over-clarifies or she over-seals and each correction sends her further from the middle. The trial data shows the size of it: medium-porosity participants routed on a binary low-or-high rule scored 64 at day 84, against 77 when routed on the full three-band rule.
So here is the advice, plainly, since nobody else is giving it. Medium porosity does best on the least interventionist routine of the three. A gentle sulphate-free wash. A mid-weight conditioner. A leave-in chosen to match strand width rather than porosity. Clarifying roughly monthly rather than fortnightly. That is a cheaper routine than either end of the scale, and for a quarter of the country it is the correct one.
The guessing figure deserves its own line, because it is the cause rather than a symptom. Only 27% of medium-porosity women place themselves correctly before testing, against 51% for low and 52% for high. Two-thirds of the band is walking into a shop with the wrong prior, and the shop has nothing on the shelf for the right one even when they arrive with it.
Rank the band across the nine measures in the table and a pattern appears that nobody has published. Medium porosity ranks second of the three on almost everything: second on air-dry time, second on build-up, second on frizz, second on products in rotation, second on spend, second on abandonment. It ranks third on only three measures, and two of those are share of the country and share of the labelled range. A band that sits in the middle of every behavioural measure and at the bottom of every commercial one is not a difficult segment. It is an unserved one.
| Measure | Medium porosity | UK average | Rank among the three bands |
|---|---|---|---|
| Share of UK women | 27% | Not applicable | 3rd |
| Guessed their band correctly | 27% | 46% | 3rd |
| Median air-dry time | 2h 10m | 2h 25m | 2nd |
| Build-up within four washes | 38% | 44% | 2nd |
| Frizz within 30 minutes | 44% | 48% | 2nd |
| Products in rotation | 7.1 | 7.6 | 2nd |
| Annual spend | £248 | £264 | 2nd |
| Abandoned per year | £72 | £81 | 2nd |
| Share of the labelled product range | 4.6% | Not applicable | 3rd |
The Zenvy Porosity Routine Builder
This asks for your strand width and density before it asks for your porosity, because that is what the 2026 data says should choose the product. Weight first, routine second, curl pattern last. Runs entirely in your browser. Nothing is sent anywhere.
The weight-selection grid this tool uses (readable with JavaScript turned off)
| Strand width | Low density | Medium density | High density |
|---|---|---|---|
| Fine | Mist or milk | Mist or milk | Mist or milk |
| Medium | Lotion | Cream | Cream or butter |
| Coarse | Cream or butter | Cream or butter | Cream or butter |
Porosity then adjusts the routine rather than the weight. Low porosity adds a monthly clarify, drops protein to six-weekly and applies everything to soaking-wet hair. Medium porosity clarifies monthly and holds no protein schedule. High porosity adds a sealing step, protein every three weeks and a leave-in under the styler. Hard water adds a chelating wash at any band. Curl pattern changes only the styler format. See Table 7 and Table 8.
A routine built from measured variables, not from a shelf category. Runs entirely in your browser. Nothing is sent anywhere.
What changes in 90 days when the routine matches the porosity[#]
UK women who switched to a porosity-matched routine rated their hair 34 out of 100 at the start and 79 out of 100 after 90 days in 2026. A matched control group who changed nothing moved from 34 to 37.
The follow-up wave recruited 416 women from the main panel and randomised them into two arms. 312 went into an intervention arm and were given a routine matched to their measured porosity. 104 went into a control arm and carried on exactly as they were. Both arms reported hair satisfaction on the same 0 to 100 scale at days 0, 7, 14, 21, 30, 45, 60, 75 and 90.
Both arms started in the same place, at 34 out of 100, which is a low number and worth sitting with. A third of the way up a satisfaction scale is where the average British woman with textured hair was rating her own hair at the start of 2026, before anybody changed anything.
The intervention arm finished at 79. The control arm finished at 37. Nothing was reformulated, no new category was invented, and nobody was given a product that did not already exist on a shelf in the UK. What changed was which product went on which head, and whether the routine matched the reading. A gap of that size, opened by matching alone, is the strongest argument in this report that the bottleneck in UK textured haircare is diagnostic rather than formulatory.
The caveat needs stating plainly rather than burying. This is self-reported satisfaction, not an instrumented measure of hair condition, and the intervention arm knew it was changing something. Some part of that movement is the knowledge of having been given a plan. The control arm’s three-point drift over 90 days gives some sense of the baseline noise, and it does not account for a gap this wide, but an unblinded satisfaction study cannot rule the effect out and this one does not pretend to.
What it does establish is a direction and a magnitude. Women who were matched to their measured porosity more than doubled their own rating of their hair inside three months, on the same instrument, against a control group that did not move. For a category where the standard promise is a better bottle, the finding that the largest available gain comes from choosing differently rather than buying differently is worth more than another formulation.
The curve is worth walking rather than summarising. Movement starts inside the first week, 34 to 41, and that matters more than the endpoint does, because week one is where most women abandon a change. By day 30 the intervention arm is at 62, nearly double baseline. Growth then flattens after day 60, which is the honest part of the finding: most of the gain lands in the first two months and the final month adds five points. Anyone selling a ninety-day transformation is selling the least productive third of it.
By band, the movement runs 34 to 81 for low porosity, 35 to 78 for medium and 33 to 77 for high. The largest gain belongs to the low-porosity group, which is consistent with the mismatch data. 23% of low-porosity women were using a heavy butter or oil every day, and removing it is a fast, visible and free change.
The Product-Match Trial is what turns this from a satisfaction survey into evidence. 524 women recruited independently of the main panel, four arms of 131, twelve weeks, the same instrument. Arm A routed on curl pattern alone finished at 61. Arm B on porosity alone finished at 71. Arm C on porosity plus density and strand width, using unlabelled products chosen by weight, finished at 76. Arm D on all three, using porosity-labelled products, finished at 79. The margin of error on a 131-person arm is plus or minus 4.1 points.
Read those four numbers slowly, because the report turns on them. Arm D beats Arm C by three points, which sits inside the margin of error. Arm D costs £57.40 per twelve-week basket against £38.90 for Arm C, which is 48% more. And Arm C, the cheapest of the four routing rules that includes porosity at all, produced 96% of the outcome of the most expensive one.
One cross-check ties the two studies together and is worth stating. The 90-day intervention arm finished at 79. The Product-Match Trial’s Arm D finished at 79. Two independent cohorts, two separate recruitments, the same instrument, the same endpoint. That is the internal validation, and it was not arranged.
| Day | Intervention | Control | Gap |
|---|---|---|---|
| 0 | 34 | 34 | 0 |
| 7 | 41 | 34 | +7 |
| 14 | 49 | 35 | +14 |
| 21 | 55 | 35 | +20 |
| 30 | 62 | 36 | +26 |
| 45 | 69 | 36 | +33 |
| 60 | 74 | 37 | +37 |
| 75 | 77 | 37 | +40 |
| 90 | 79 | 37 | +42 |
| Arm | Routing rule | Day-84 score | Mean 12-week basket | Cost per point above baseline |
|---|---|---|---|---|
| A | Curl pattern alone | 61 | £41.20 | £1.53 |
| B | Porosity alone | 71 | £49.80 | £1.35 |
| C | Porosity plus density and strand width, unlabelled products chosen by weight | 76 | £38.90 | £0.93 |
| D | All three, porosity-labelled products | 79 | £57.40 | £1.28 |
How to pay less and do better: eleven changes ranked by measured effect[#]
The single most effective change a UK woman can make to her hair routine in 2026 costs nothing: matching product weight to strand width and density moved satisfaction 19 points in twelve weeks. The two most expensive changes on our list moved it three points and two.
The measurement first, because a ranking is only as defensible as the thing it was measured against. Each change was isolated within the Product-Match Trial and the 90-day study and scored as the mean movement on the same 0 to 100 instrument at day 84, against a matched participant who did not make that change. The margin of error is plus or minus 4.1 points, so anything below five points is reported as directional rather than proven, and the table labels it that way.
The eleven in order, with the cost attached to each.
1. Match product weight to strand width and density. Plus 19 points, at
£0. This is a change in how you choose, not in what you spend.
2. Clarify on a schedule, fortnightly in very hard water and monthly in soft.
Plus 14 points, about £28 a year.
3. Apply leave-in to soaking-wet hair rather than towel-dried. Plus 11 points,
£0.
4. Drop the daily heavy butter if you measure low porosity. Plus 11 points, and
it saves about £34 a year.
5. Retest porosity after any colour or chemical service. Plus 9 points,
£0.
6. Reduce protein to six-weekly if you measure low porosity. Plus 8 points,
saving about £22 a year.
7. Sleep on satin. Plus 8 points, £8 to £16 once.
8. Fit a shower filter in a very hard water area. Plus 7 points, £24 to
£38 plus about £9 a year in cartridges.
9. Water-first layering, applying while wet and sealing after. Plus 6 points,
£0.
10. Switch to a porosity-labelled product line. Plus 3 points, inside the
margin of error, at about £80 a year more.
11. Add a bond-building treatment. Plus 2 points, inside the margin of error,
at £28 to £42 per treatment.
Now say the conclusion out loud rather than leaving a reader to infer it. Six of the top seven changes are free or cost under £30 once. The two changes at the bottom of the list are the two most heavily marketed categories in UK textured haircare. The best thing you can do to your hair costs nothing, and the most expensive things you can buy for it are the two least likely to show up in a measurement.
None of that makes bond-building or porosity-labelled ranges worthless. It makes them the last two things to buy rather than the first, and it makes the order of operations the finding. The twelve-week audit below turns this list into a saveable plan with a tick, a cross and a not-yet against each line.
Two things about the ranking need saying before anyone quotes it. Every effect is measured against a matched participant who did not make that change, so these are not cumulative and stacking all eleven would not move anyone 98 points. And the ordering is a UK ordering. A shower filter earns seventh place here because most of England drinks hard water. In Scotland the same change would rank lower, and the table would look different if we had fielded it in Glasgow alone.
The order of operations is the finding, more than any individual line. Start with the two free changes at the top, which between them are worth 30 points and cost nothing. Add the scheduled clarifying wash if you live in a hard-water region. Then, and only then, look at whether a product line or a treatment is worth adding. Reversing that order is what produces the sixteen purchases a high-porosity woman currently makes before she finds a routine that works, and the £118 a year she abandons on the way.
| Rank | Change | Points gained at day 84 | Cost | Cost per point | Proven or directional |
|---|---|---|---|---|---|
| 1 | Match product weight to strand width and density | +19 | £0 | £0.00 | Proven |
| 2 | Clarify on a schedule, fortnightly in very hard water and monthly in soft | +14 | About £28 a year | £2.00 | Proven |
| 3 | Apply leave-in to soaking-wet hair, not towel-dried | +11 | £0 | £0.00 | Proven |
| 4 | Drop the daily heavy butter if you measure low porosity | +11 | Saves about £34 a year | Saves money | Proven |
| 5 | Retest porosity after any colour or chemical service | +9 | £0 | £0.00 | Proven |
| 6 | Reduce protein to six-weekly if you measure low porosity | +8 | Saves about £22 a year | Saves money | Proven |
| 7 | Sleep on satin | +8 | £8 to £16, once | £1.50 | Proven |
| 8 | Fit a shower filter in a very hard water area | +7 | £24 to £38 plus about £9 a year in cartridges | £4.43 | Proven |
| 9 | Water-first layering, apply while wet and seal after | +6 | £0 | £0.00 | Proven |
| 10 | Switch to a porosity-labelled product line | +3 | About £80 a year more | £26.67 | Directional |
| 11 | Add a bond-building treatment | +2 | £28 to £42 per treatment | £17.50 | Directional |
The 12-Week Porosity Audit
Twelve steps, in order, over twelve weeks. Tap an item once to mark it done and twice to mark it not applicable, which takes it out of the count rather than holding it against you. Your progress is saved in this browser only. Nothing is sent anywhere.
Saved in this browser with localStorage. Nothing is sent anywhere.
Porosity by season: what changes between February and August[#]
Measured high porosity rises from 33% in February to 37% in August across the same 612 UK women. Roughly one in nine women who reads as high porosity in August reads as medium in February, on the same hair.
For a report built on a self-administered protocol this is the most methodologically important section on the page, and it is new for 2026. If the instrument gives a different answer in different months, a reader is entitled to know by how much before she trusts the headline.
612 of the original 1,000 panellists re-ran the identical six-signal protocol between 4 and 18 August 2026, with the same instructions and the same scoring. The re-contact sample matches the original on age, region and curl pattern to within two points on every cell, so the movement is not a composition effect.
High porosity moves from 33% to 37%. Low porosity moves from 40% to 37%. Medium holds almost still at 27% to 26%. Median air-dry time falls from 2 hours 25 minutes to 1 hour 50, because ambient temperature is doing work the protocol cannot see. Build-up within four washes falls from 44% to 39%, because people wash more often in summer. Frizz within 30 minutes rises sharply from 48% to 63%, because the dew point is higher. Products in rotation rise from 7.6 to 8.4 and monthly spend from £22 to £24.
The interpretation needs stating carefully. Cuticle structure does not change seasonally in any meaningful way over six months in a temperate climate. What changes is every one of the environmental confounders the six signals are sensitive to. Four points of the national high-porosity figure is a seasonal artefact, and any single reading taken in August will skew high.
That is actionable rather than merely interesting. If you test in summer and get a high-porosity result that surprises you, retest in the cooler months before rebuilding a routine around it. If you test in winter and get a low-porosity result, the frizz signal in particular is under-reading and the composite will lean low with it. The protocol carries a seasonal correction for exactly this, down-weighting the frizz and dry-time signals for a reading taken in the summer months, and we are not aware of another porosity instrument that does. The humidity side of the same problem is the subject of the UK Frizz Index 2026.
One consequence for anyone quoting this report. The headline distribution is the February reading, because February is the fieldwork month and the series has to stay comparable year on year. We are saying so here, in the report, so that nobody has to take our word for it later.
Two details keep the re-contact honest and both belong in the open. The 612 who came back are 61% of the original panel, and a re-contact wave always risks losing the least engaged respondents first, which would bias a satisfaction measure. It biases a porosity measure far less, because the six signals ask what happened rather than how somebody felt about it. And the August instructions were word for word the February ones, including the requirement to test on hair washed within 48 hours and free of styling product, so the difference between the two readings is not a difference in how the test was explained.
What the season effect really argues for is writing the date down. A porosity reading with no date attached is close to useless a year later, and a reading taken in a heatwave is not the same instrument as one taken in February. The twelve-week audit further down this page opens by asking for the score and the date together, and the date is the half most people will be tempted to skip.
The self-test on this page carries that correction rather than leaving it to the reader. It asks which month you are testing in, and from June to September it takes a quarter off the dry-time weight and a quarter off the frizz weight, because those two signals carry almost the whole of the seasonal movement. It is the only seasonal adjustment we know of in any porosity instrument, and it is the difference between a reading you can hold against last year's and one you cannot.
| Measure | February | August | Movement |
|---|---|---|---|
| Measure high porosity | 33% | 37% | +4 pts |
| Measure medium porosity | 27% | 26% | -1 pt |
| Measure low porosity | 40% | 37% | -3 pts |
| Median air-dry time | 2h 25m | 1h 50m | -35 min |
| Build-up within four washes | 44% | 39% | -5 pts |
| Frizz within 30 minutes of humid air | 48% | 63% | +15 pts |
| Products in rotation | 7.6 | 8.4 | +0.8 |
| Monthly haircare spend | £22 | £24 | +£2 |
What changed since 2024[#]
Between 2024 and 2026 the share of UK women who had heard of hair porosity rose 14 points, and the share who could identify it correctly rose three. The category sold the word, not the measurement.
Zenvy ran a smaller pilot in February 2024. 604 UK women, the same six-signal protocol, the same instrument. It was never published. It is published here as the baseline, because a series with no back-year is an assertion and a series with one is a trend.
Eight comparisons. Heard the term 58% to 72%. Ever tested 31% to 39%. Confident they know their own band 14% to 19%. Used the float test, among testers, 51% to 43%. Bought a porosity-labelled product in the last twelve months 27% to 44%. Annual spend £229 to £264. Product abandoned per year £71 to £81. Mismatch rate on retest 64% to 61%.
Read together rather than one at a time, those eight lines make the headline. Awareness rose 14 points. Purchase of porosity-labelled product rose 17 points, which is faster than awareness. Accuracy rose three points. Waste rose £10. The two fastest-moving lines in two years are the two that make the category money, and the slowest-moving line is the one that would save the consumer money.
That is a structural finding rather than a moral one, and it should not be read as an accusation of bad faith. A brand can only sell what it can label, and porosity is genuinely difficult to measure at the point of sale, which is why nobody has built a range around a measurement nobody can take in a shop. The shape of the incentive explains the shape of the movement. It still leaves the consumer where she started.
There is one line of real good news in the eight and it deserves its own paragraph. The float test’s share of testers fell eight points, from 51% to 43%. The least reliable method in common use is losing ground. Slowly, and from a high base, but losing it. At that rate it stops being Britain’s most popular porosity test in 2032.
Two data points make a line rather than a curve, so the next section projects them forward and states every assumption it uses out loud, including the one that would break it.
Why the 2024 pilot went unpublished is a fair question and the answer is unglamorous. At 604 respondents it was under-powered for the regional cut, which was the cut we were most interested in at the time, and a national distribution on its own did not feel like enough to put a name to. Holding it back was the right call in 2024 and the wrong one to keep making in 2026, because a back-year is worth more than a headline.
What two points can and cannot do is worth being blunt about. They establish direction and they establish rough magnitude. They cannot distinguish a straight line from the early part of a curve, they cannot separate a real behavioural shift from a change in how willing people are to say they have heard of something, and they cannot rule out that the awareness jump is mostly the word appearing on more packaging. That last one is not a criticism of the finding. It is the finding.
| Measure | 2024 | 2026 | Movement |
|---|---|---|---|
| Heard the term | 58% | 72% | +14 pts |
| Ever tested | 31% | 39% | +8 pts |
| Confident they know their own | 14% | 19% | +5 pts |
| Used the float test, among testers | 51% | 43% | -8 pts |
| Bought a porosity-labelled product in the last 12 months | 27% | 44% | +17 pts |
| Annual spend | £229 | £264 | +£35 |
| Abandoned per year | £71 | £81 | +£10 |
| Mismatch rate on retest | 64% | 61% | -3 pts |
The five-year view: where UK porosity goes to 2031[#]
On current trajectories 89% of UK women will have heard of hair porosity by 2031 and 58% will have tested it, but 44% will still be carrying a label that does not match their hair. Awareness is projected to reach saturation eleven years before accuracy does.
Say what this is before anyone quotes it. A projection, not a forecast. Two data points and a damping factor. We publish the assumptions in the final column of the table so that a reader who disagrees with one of them can rebuild the line herself.
The method, plainly. Each line is extrapolated from the 2024 to 2026 movement with a logistic damping factor applied as the measure approaches its natural ceiling. Awareness cannot exceed 100%. Mismatch cannot fall below the residual error of the instrument, which we set at 20%. Spend is extrapolated in nominal 2026 pounds with no inflation adjustment, because inflating a self-reported spend figure adds a precision the underlying data does not have.
Six lines, for 2026, 2028 and 2031. Heard the term 72, 81, 89. Ever tested 39, 47, 58. Confident they know their own band 19, 26, 35. Mismatch rate on retest 61, 55, 44. Annual spend £264, £291, £328. Product abandoned per year £81, £79, £68.
Abandonment is the only line that bends downward, and it only bends because the testing line bends upward. That dependency is the whole model. If testing stalls, if the 39% simply does not move, abandonment carries on rising with spend and the 2031 figure is £96 rather than £68. Both numbers belong in the table, and both are in it. A projection that shows only the optimistic branch is a marketing document.
Three things would break the projection, and naming them is what makes it worth reading. First, a standardised, cheap, physical porosity test reaching mass retail would move the accuracy line far faster than this model allows, because the model assumes the instrument stays a self-administered one. Second, a shift in UK water treatment would move the regional distribution and with it the national high-porosity figure, independent of anything a consumer does. Third, the ageing profile of the UK adult female population pushes the national high-porosity share up by roughly a point every five years on demographics alone. That third one is already in the model, and as far as we can tell nobody has previously accounted for it.
The commitment that goes with publishing a projection is re-fielding it. February each year, the same instrument, published in May, so that the 2031 edition can be checked against this paragraph.
How to read a damped extrapolation, for anyone who has not built one. The undamped version of the awareness line would put the country at 100% by 2031, which is obviously wrong, because the last few points of any awareness measure are the hardest to win and some share of any population will never encounter the term at all. Damping pulls the curve towards a ceiling instead of through it. The choice of ceiling is a judgement rather than a calculation, and ours is stated in the table so it can be argued with.
The most likely way this projection is wrong is that it is too pessimistic about accuracy and too optimistic about waste, and both errors have the same cause. The model assumes the measurement stays where it is today, a self-administered protocol run at home by whoever can be bothered. Any change to that assumption moves both lines at once, and it moves them faster than anything a brand could do with a formulation.
| Measure | 2026 actual | 2028 projected | 2031 projected | Assumption |
|---|---|---|---|---|
| Heard the term | 72% | 81% | 89% | Damped as the measure approaches a 100% ceiling |
| Ever tested | 39% | 47% | 58% | 2024 to 2026 movement carried forward and damped |
| Confident they know their own | 19% | 26% | 35% | Tracks the testing line with a two-year lag |
| Mismatch rate on retest | 61% | 55% | 44% | Floored at the 20% residual error of the instrument |
| Annual spend | £264 | £291 | £328 | Nominal 2026 pounds, no inflation adjustment |
| Abandoned per year | £81 | £79 | £68 | Falls only while testing keeps rising. If testing stalls at 39%, the 2031 figure is £96 |
What this means for UK haircare in 2026[#]
61% of UK women have never tested their hair porosity, and 43% of those who have used the most confounded of the six available signals. Fixing the diagnosis, rather than the shopping, is the single highest-value change available to the UK textured-hair market in 2026.
Six implications follow from the tables above, and none of them needs a figure that has not already appeared on this page.
One, the category is mis-segmented. Ranges built on curl pattern alone get it right at the extremes and guess in the middle, where the porosity split at 3B is a three-way tie at 34, 31 and 35. Curl pattern explains 11% of whether a product works. Porosity explains 27%. Density and strand width explain 19%. The axis the shelves are organised by is the weakest of the three.
Two, geography is a product variable. A 265 mg/l hardness gap between the East of England and Scotland produces a 21-point gap in measured high porosity, and a third of women in very hard water move a band after two clarifying washes. Regional water is not an edge case in the UK. It is most of the country, and it is currently absent from almost every range architecture we have seen.
Three, the middle band has no market. 27% of UK women, 4.6% of the labelled range, and the worst self-assessment accuracy of the three bands at 27%. A quarter of the country is being asked to read guidance written for somebody else and take half of it.
Four, diagnosis beats formulation for most women. A 42-point satisfaction gap opened inside 90 days without anyone changing what a product was made of. They changed which product went on which head.
Five, the abandonment figure is addressable and it is regressive. £81 a year each is not fickleness. It is the downstream cost of 61% never testing and 43% of testers using the wrong instrument, and it falls hardest on the households least able to absorb it: 34.5% of spend wasted under £20,000 against 26.2% over £80,000.
Six, labelling is worth less than it costs. Three points on a hundred-point scale at a 48% premium, which is a gap the trial could not distinguish from noise. The section after this one sets that out in full.
One thing the six do not say is that anybody has been lazy about it. 39% of UK women have tested their porosity, which is a great many people willing to do unpaid work on a Sunday afternoon to understand their own hair. 43% of them used the method most likely to hand them the wrong answer, because it is the method the category made visible. The effort is already there. What is missing is a test worth the effort, and supplying one free would move more outcomes than another reformulation.
For anyone selling into this market, the order of the six is the useful part. Segmentation first, because it is structural and it is wrong. Geography second, because it is cheap to fix and nobody is doing it. The middle band third, because it is the largest unserved group in UK textured haircare and it has been sitting in plain sight since the category invented itself.
For a reader, the practical version of all six fits in three lines. Run the six signals rather than one. Write the result down with the date next to it. Retest after any colour or chemical service, because the reading moves. Everything else on this page is detail underneath those three sentences. The wider category picture sits in the UK Haircare Spend Audit 2026 and the UK Curl Report 2026.
| Finding | 2026 figure | What it changes | Source table |
|---|---|---|---|
| Working without a reliable porosity reading | 78% | Diagnosis is the bottleneck, not product choice | Table 1 |
| Porosity split at 3B hair | 34 / 31 / 35 | Curl-pattern-only ranges cannot serve the middle | Table 5 |
| Explained variance, curl pattern against porosity | 11% v 27% | The shelf taxonomy is the weakest predictor | Table 8 |
| Hardness gap, East of England to Scotland | 265 mg/l | Regional water is a product variable | Table 9 |
| Medium porosity share of the labelled range | 4.6% | A quarter of the country has no category | Table 19 |
| 90-day satisfaction gap after correction | +42 points | Matching beats reformulating | Table 20 |
| Waste as a share of spend, lowest income band | 34.5% | The cost falls hardest where it hurts most | Table 13 |
| Porosity labelling advantage | +3 points at +48% cost | The premium is not supported by the measurement | Table 21 |
What predicts product performance: density, weight and porosity compared[#]
Porosity-labelled products scored three points higher than unlabelled products chosen by weight over twelve weeks in 2026, a gap inside the plus or minus 4.1 margin of error. The labelled basket cost 48% more.
This is the analytical pay-off of the report and it belongs at the end, because it cannot be read properly until the explained-variance table, the four trial arms and the ranked changes are all already on the page.
The design first. In the Product-Match Trial, four arms of 131 women each ran for twelve weeks. Arm C was routed on porosity plus density and strand width and given unlabelled products chosen purely by weight, meaning the lightest formulation that would do the job for that strand width and that density. Arm D was routed on the same three variables and given porosity-labelled products from the ranges that market on exactly that promise. Arm C finished at 76 out of 100. Arm D finished at 79. The margin of error on a 131-person arm is plus or minus 4.1 points, so a three-point gap cannot be distinguished from noise.
Then the price. Arm C’s mean twelve-week basket was £38.90. Arm D’s was £57.40. That is £18.50 more, or 48%. Annualised, roughly £80 a year for a difference the trial could not prove exists.
So, flatly, for a reader deciding what to put in a basket this week: if you can identify your strand width and your density, the porosity label on the bottle adds very little. Buy the weight.
Two qualifications, both real, and leaving either out would overstate the result. The first is the horizon. The trial measures self-reported satisfaction over twelve weeks, not strand condition over years, and a porosity-formulated product may do something on a longer timescale that a satisfaction score at day 84 cannot see. The second is that the effect is not zero everywhere. Among high-porosity participants specifically the gap was four points rather than three, still inside the margin but the largest gap in any sub-group we measured. If porosity labelling earns its premium anywhere, it earns it there.
The number to act on is cost per point above baseline. Arm C buys a point of satisfaction for £0.93, which is the cheapest of the four. Arm D follows at £1.28, Arm B at £1.35, and Arm A, routed on curl pattern alone, is the most expensive at £1.53 for the worst outcome of the four. The cheapest routing rule that includes porosity produced 96% of the outcome of the most expensive one, and it is the rule this report recommends.
What chosen by weight meant in practice is worth spelling out, because it is the whole mechanism of Arm C. Each participant’s strand width and density were recorded, mapped to a weight band running from mist through lotion, cream and butter, and then matched to the lightest formulation in the trial stock that sat in that band. Nobody in Arm C saw a porosity claim on a label. The routing used porosity to decide how often to clarify and whether protein belonged in the routine at all, and it used weight to decide what went on the hair.
That split is the practical version of the whole report. Porosity decides the schedule. Strand width and density decide the product. Curl pattern, which is the only one of the three that most shelves are organised by, decides comparatively little on its own.
Methodology[#]
Study 1. The Zenvy Beauty UK Porosity Panel 2026. 1,000 UK women aged 18 to 65, fielded from 9 to 23 February 2026 through an online consumer panel and weighted to be nationally representative on age and Government Office Region. Twenty questions plus the six-signal protocol. Fields captured: porosity awareness; test history and method; confidence in their own band; the six signals; whether anyone else had ever given them a porosity label and who; curl pattern on a nine-image shuffle grid; outward postcode; annual haircare spend, banded and midpoint-coded; the number and approximate value of products bought and then abandoned; the number of products tried before a working routine; chemical and colour history over three years; daily butter or heavy oil use; and protein use in the last 90 days with the reported result.
Study 2. The Zenvy Beauty Curl Identifier dataset 2026. 8,847 completed responses to Zenvy’s on-site curl diagnostic, UK IP addresses only, collected between March 2025 and January 2026. Used for the curl-pattern cross-tabulation and as a deliberate self-selecting contrast set. It is never merged into the national panel and is labelled separately wherever it appears.
Study 3. The Zenvy Beauty 90-Day Porosity Correction Study 2026. 416 panellists recruited from Study 1 and randomised into a porosity-matched routine arm of 312 and an unchanged control arm of 104, reporting hair satisfaction on a 0 to 100 scale at days 0, 7, 14, 21, 30, 45, 60, 75 and 90.
Study 4. The Zenvy UK order database. A rolling 24 months of UK order history to 31 January 2026, covering basket composition, repeat-purchase behaviour, category spend and product-abandonment rate. Used to sense-check the self-reported spend and abandonment figures in the panel.
The protocol. Porosity was classified using six self-administered signals rather than any single test: strand float, spray absorption, air-dry time, washes to build-up, slip-test roughness and time to frizz in humid air. Each signal was scored, weighted and summed, and the band was read from the composite. The float test was deliberately down-weighted because it is the most confounded of the six, being sensitive to product residue, strand weight and surface tension independently of cuticle state. Respondents were asked to self-assign a band before running the protocol, so any comparison between what a woman expected and what she measured is within-person rather than between-groups.
Water hardness. The hardness figures on this page are Zenvy’s own compilation of publicly available UK water-supply records. Zone-level hardness values were collected for every outward postcode represented in the panel, converted to mg/l calcium carbonate where reported in other units, and averaged to Government Office Region weighted by the number of panellists in each zone. We publish regional means only. Zone-level hardness varies substantially within every region, and a regional mean is a poor guide to any individual address.
Screening and quotas. Respondents were screened for hair length sufficient to run every signal in the protocol, since strand float, slip and dry time are not measurable on very short hair. Age quotas were matched to the UK adult female population and region quotas to Government Office Region shares, with a soft ethnicity quota to prevent under-representation of Type 3 and Type 4 hair.
Limitations. Every measure on this page is self-reported. Porosity was self-administered rather than instrumented, and there is no laboratory verification of any classification. Air-dry time varies with hair length and density as well as with porosity, and we did not control for either. The 90-day study was unblinded: participants knew they had changed something, and some part of the movement is that. Water hardness figures are regional means and hardness varies by supply zone within every region. Spend and abandonment figures are self-reported in bands and midpoint-coded, which is a blunter instrument than till data. The Curl Identifier dataset is self-selecting, is reported separately from the national panel throughout, and is never merged into it. Where this edition reports a cut with a small base, the base is printed in the table caption and should be quoted with the figure.
The full anonymised dataset is available on request to emma@zenvy-beauty.com.
The Porosity Data Index
Every figure published on this page, indexed back to the table it came from. Search it, sort it, and copy any row with its citation and a link to the exact table. Runs entirely in your browser. Nothing is sent anywhere.
| Figure | Measure | Cut | Dimension | Table | Base |
|---|---|---|---|---|---|
| 72% | % | Heard the term "hair porosity" | National | Table 1 | 1,000 |
| 720 | Estimated base | Heard the term "hair porosity" | National | Table 1 | 1,000 |
| 39% | % | Have ever tested their own porosity | National | Table 1 | 1,000 |
| 390 | Estimated base | Have ever tested their own porosity | National | Table 1 | 1,000 |
| 61% | % | Have never tested their own porosity | National | Table 1 | 1,000 |
| 610 | Estimated base | Have never tested their own porosity | National | Table 1 | 1,000 |
| 19% | % | Confident they know their own band | National | Table 1 | 1,000 |
| 190 | Estimated base | Confident they know their own band | National | Table 1 | 1,000 |
| 44% | % | Bought a porosity-labelled product in the last 12 months | National | Table 1 | 1,000 |
| 440 | Estimated base | Bought a porosity-labelled product in the last 12 months | National | Table 1 | 1,000 |
| 78% | % | Working without a reliable porosity reading | National | Table 1 | 1,000 |
| 780 | Estimated base | Working without a reliable porosity reading | National | Table 1 | 1,000 |
| 0.5 | Weight in the composite | Strand float | Signal | Table 2 | 1,000 |
| 1.0 | Weight in the composite | Spray absorption | Signal | Table 2 | 1,000 |
| 1.25 | Weight in the composite | Air-dry time | Signal | Table 2 | 1,000 |
| 1.0 | Weight in the composite | Washes to build-up | Signal | Table 2 | 1,000 |
| 1.0 | Weight in the composite | Slip-test roughness | Signal | Table 2 | 1,000 |
| 1.0 | Weight in the composite | Minutes to frizz in humid air | Signal | Table 2 | 1,000 |
| 40% | UK national panel | Low | Porosity band | Table 3 | 1,000 panel, 8,847 Curl Identifier |
| 28% | Zenvy Curl Identifier users | Low | Porosity band | Table 3 | 1,000 panel, 8,847 Curl Identifier |
| -12 pts | Gap | Low | Porosity band | Table 3 | 1,000 panel, 8,847 Curl Identifier |
| 6.4 | Products in rotation | Low | Porosity band | Table 3 | 1,000 panel, 8,847 Curl Identifier |
| 27% | UK national panel | Medium | Porosity band | Table 3 | 1,000 panel, 8,847 Curl Identifier |
| 25% | Zenvy Curl Identifier users | Medium | Porosity band | Table 3 | 1,000 panel, 8,847 Curl Identifier |
| -2 pts | Gap | Medium | Porosity band | Table 3 | 1,000 panel, 8,847 Curl Identifier |
| 7.1 | Products in rotation | Medium | Porosity band | Table 3 | 1,000 panel, 8,847 Curl Identifier |
| 33% | UK national panel | High | Porosity band | Table 3 | 1,000 panel, 8,847 Curl Identifier |
| 47% | Zenvy Curl Identifier users | High | Porosity band | Table 3 | 1,000 panel, 8,847 Curl Identifier |
| +14 pts | Gap | High | Porosity band | Table 3 | 1,000 panel, 8,847 Curl Identifier |
| 9.8 | Products in rotation | High | Porosity band | Table 3 | 1,000 panel, 8,847 Curl Identifier |
| 43% | Share of testers | Float test | Test method | Table 4 | 390 who have tested |
| 54% | Agreement with the six-signal composite | Float test | Test method | Table 4 | 390 who have tested |
| 21% | Share of testers | Spray absorption | Test method | Table 4 | 390 who have tested |
| 78% | Agreement with the six-signal composite | Spray absorption | Test method | Table 4 | 390 who have tested |
| 14% | Share of testers | Dry-time observation | Test method | Table 4 | 390 who have tested |
| 84% | Agreement with the six-signal composite | Dry-time observation | Test method | Table 4 | 390 who have tested |
| 9% | Share of testers | Slide or slip test | Test method | Table 4 | 390 who have tested |
| 69% | Agreement with the six-signal composite | Slide or slip test | Test method | Table 4 | 390 who have tested |
| 8% | Share of testers | Salon assessment | Test method | Table 4 | 390 who have tested |
| 61% | Agreement with the six-signal composite | Salon assessment | Test method | Table 4 | 390 who have tested |
| 5% | Share of testers | Online quiz | Test method | Table 4 | 390 who have tested |
| 58% | Agreement with the six-signal composite | Online quiz | Test method | Table 4 | 390 who have tested |
| 52% | Low | 2A | Curl pattern | Table 5 | 1,000 |
| 31% | Medium | 2A | Curl pattern | Table 5 | 1,000 |
| 17% | High | 2A | Curl pattern | Table 5 | 1,000 |
| 48% | Low | 2B | Curl pattern | Table 5 | 1,000 |
| 32% | Medium | 2B | Curl pattern | Table 5 | 1,000 |
| 20% | High | 2B | Curl pattern | Table 5 | 1,000 |
| 44% | Low | 2C | Curl pattern | Table 5 | 1,000 |
| 32% | Medium | 2C | Curl pattern | Table 5 | 1,000 |
| 24% | High | 2C | Curl pattern | Table 5 | 1,000 |
| 39% | Low | 3A | Curl pattern | Table 5 | 1,000 |
| 33% | Medium | 3A | Curl pattern | Table 5 | 1,000 |
| 28% | High | 3A | Curl pattern | Table 5 | 1,000 |
| 34% | Low | 3B | Curl pattern | Table 5 | 1,000 |
| 31% | Medium | 3B | Curl pattern | Table 5 | 1,000 |
| 35% | High | 3B | Curl pattern | Table 5 | 1,000 |
| 29% | Low | 3C | Curl pattern | Table 5 | 1,000 |
| 30% | Medium | 3C | Curl pattern | Table 5 | 1,000 |
| 41% | High | 3C | Curl pattern | Table 5 | 1,000 |
| 24% | Low | 4A | Curl pattern | Table 5 | 1,000 |
| 29% | Medium | 4A | Curl pattern | Table 5 | 1,000 |
| 47% | High | 4A | Curl pattern | Table 5 | 1,000 |
| 20% | Low | 4B | Curl pattern | Table 5 | 1,000 |
| 27% | Medium | 4B | Curl pattern | Table 5 | 1,000 |
| 53% | High | 4B | Curl pattern | Table 5 | 1,000 |
| 16% | Low | 4C | Curl pattern | Table 5 | 1,000 |
| 25% | Medium | 4C | Curl pattern | Table 5 | 1,000 |
| 59% | High | 4C | Curl pattern | Table 5 | 1,000 |
| 51% | Low | 18-24 | Age band | Table 6 | 1,000 |
| 28% | Medium | 18-24 | Age band | Table 6 | 1,000 |
| 21% | High | 18-24 | Age band | Table 6 | 1,000 |
| 2h 55m | Median air-dry time | 18-24 | Age band | Table 6 | 1,000 |
| 0.6 | Chemical services in the last 3 years | 18-24 | Age band | Table 6 | 1,000 |
| 46% | Low | 25-34 | Age band | Table 6 | 1,000 |
| 28% | Medium | 25-34 | Age band | Table 6 | 1,000 |
| 26% | High | 25-34 | Age band | Table 6 | 1,000 |
| 2h 40m | Median air-dry time | 25-34 | Age band | Table 6 | 1,000 |
| 1.1 | Chemical services in the last 3 years | 25-34 | Age band | Table 6 | 1,000 |
| 40% | Low | 35-44 | Age band | Table 6 | 1,000 |
| 28% | Medium | 35-44 | Age band | Table 6 | 1,000 |
| 32% | High | 35-44 | Age band | Table 6 | 1,000 |
| 2h 25m | Median air-dry time | 35-44 | Age band | Table 6 | 1,000 |
| 1.4 | Chemical services in the last 3 years | 35-44 | Age band | Table 6 | 1,000 |
| 35% | Low | 45-54 | Age band | Table 6 | 1,000 |
| 26% | Medium | 45-54 | Age band | Table 6 | 1,000 |
| 39% | High | 45-54 | Age band | Table 6 | 1,000 |
| 2h 05m | Median air-dry time | 45-54 | Age band | Table 6 | 1,000 |
| 1.7 | Chemical services in the last 3 years | 45-54 | Age band | Table 6 | 1,000 |
| 29% | Low | 55-65 | Age band | Table 6 | 1,000 |
| 25% | Medium | 55-65 | Age band | Table 6 | 1,000 |
| 46% | High | 55-65 | Age band | Table 6 | 1,000 |
| 1h 50m | Median air-dry time | 55-65 | Age band | Table 6 | 1,000 |
| 1.9 | Chemical services in the last 3 years | 55-65 | Age band | Table 6 | 1,000 |
| 40% | Low | All UK women | Age band | Table 6 | 1,000 |
| 27% | Medium | All UK women | Age band | Table 6 | 1,000 |
| 33% | High | All UK women | Age band | Table 6 | 1,000 |
| 2h 25m | Median air-dry time | All UK women | Age band | Table 6 | 1,000 |
| 1.3 | Chemical services in the last 3 years | All UK women | Age band | Table 6 | 1,000 |
| 19% | Share who can identify their own | Strand width | Diagnostic variable | Table 7 | 1,000 |
| 44% | Share currently using a mismatched product weight | Strand width | Diagnostic variable | Table 7 | 1,000 |
| 14% | Share who can identify their own | Density | Diagnostic variable | Table 7 | 1,000 |
| 51% | Share currently using a mismatched product weight | Density | Diagnostic variable | Table 7 | 1,000 |
| 47% | Share currently using a mismatched product weight | Either variable mismatched | Diagnostic variable | Table 7 | 1,000 |
| 11% | Explained variance | Curl pattern alone | Diagnostic rule | Table 8 | 524 |
| 61 | Day-84 satisfaction score | Curl pattern alone | Diagnostic rule | Table 8 | 524 |
| GBP 41.20 | Mean 12-week basket | Curl pattern alone | Diagnostic rule | Table 8 | 524 |
| 19% | Explained variance | Density and strand width alone | Diagnostic rule | Table 8 | 524 |
| 68 | Day-84 satisfaction score | Density and strand width alone | Diagnostic rule | Table 8 | 524 |
| GBP 36.10 | Mean 12-week basket | Density and strand width alone | Diagnostic rule | Table 8 | 524 |
| 27% | Explained variance | Porosity alone | Diagnostic rule | Table 8 | 524 |
| 71 | Day-84 satisfaction score | Porosity alone | Diagnostic rule | Table 8 | 524 |
| GBP 49.80 | Mean 12-week basket | Porosity alone | Diagnostic rule | Table 8 | 524 |
| 38% | Explained variance | Porosity and density, unlabelled products chosen by weight | Diagnostic rule | Table 8 | 524 |
| 76 | Day-84 satisfaction score | Porosity and density, unlabelled products chosen by weight | Diagnostic rule | Table 8 | 524 |
| GBP 38.90 | Mean 12-week basket | Porosity and density, unlabelled products chosen by weight | Diagnostic rule | Table 8 | 524 |
| 41% | Explained variance | All three, porosity-labelled products | Diagnostic rule | Table 8 | 524 |
| 79 | Day-84 satisfaction score | All three, porosity-labelled products | Diagnostic rule | Table 8 | 524 |
| GBP 57.40 | Mean 12-week basket | All three, porosity-labelled products | Diagnostic rule | Table 8 | 524 |
| 312 | Mean hardness (mg/l CaCO3) | East of England | Region | Table 9 | 1,000 |
| 43% | Measure high porosity | East of England | Region | Table 9 | 1,000 |
| 64% | Weekly build-up | East of England | Region | Table 9 | 1,000 |
| 33% | Moved down a band after two clarifying washes | East of England | Region | Table 9 | 1,000 |
| 298 | Mean hardness (mg/l CaCO3) | London | Region | Table 9 | 1,000 |
| 41% | Measure high porosity | London | Region | Table 9 | 1,000 |
| 62% | Weekly build-up | London | Region | Table 9 | 1,000 |
| 32% | Moved down a band after two clarifying washes | London | Region | Table 9 | 1,000 |
| 285 | Mean hardness (mg/l CaCO3) | South East | Region | Table 9 | 1,000 |
| 39% | Measure high porosity | South East | Region | Table 9 | 1,000 |
| 59% | Weekly build-up | South East | Region | Table 9 | 1,000 |
| 30% | Moved down a band after two clarifying washes | South East | Region | Table 9 | 1,000 |
| 264 | Mean hardness (mg/l CaCO3) | East Midlands | Region | Table 9 | 1,000 |
| 38% | Measure high porosity | East Midlands | Region | Table 9 | 1,000 |
| 57% | Weekly build-up | East Midlands | Region | Table 9 | 1,000 |
| 29% | Moved down a band after two clarifying washes | East Midlands | Region | Table 9 | 1,000 |
| 187 | Mean hardness (mg/l CaCO3) | West Midlands | Region | Table 9 | 1,000 |
| 33% | Measure high porosity | West Midlands | Region | Table 9 | 1,000 |
| 48% | Weekly build-up | West Midlands | Region | Table 9 | 1,000 |
| 21% | Moved down a band after two clarifying washes | West Midlands | Region | Table 9 | 1,000 |
| 152 | Mean hardness (mg/l CaCO3) | Yorkshire and the Humber | Region | Table 9 | 1,000 |
| 30% | Measure high porosity | Yorkshire and the Humber | Region | Table 9 | 1,000 |
| 43% | Weekly build-up | Yorkshire and the Humber | Region | Table 9 | 1,000 |
| 15% | Moved down a band after two clarifying washes | Yorkshire and the Humber | Region | Table 9 | 1,000 |
| 141 | Mean hardness (mg/l CaCO3) | South West | Region | Table 9 | 1,000 |
| 29% | Measure high porosity | South West | Region | Table 9 | 1,000 |
| 41% | Weekly build-up | South West | Region | Table 9 | 1,000 |
| 14% | Moved down a band after two clarifying washes | South West | Region | Table 9 | 1,000 |
| 118 | Mean hardness (mg/l CaCO3) | North East | Region | Table 9 | 1,000 |
| 27% | Measure high porosity | North East | Region | Table 9 | 1,000 |
| 37% | Weekly build-up | North East | Region | Table 9 | 1,000 |
| 11% | Moved down a band after two clarifying washes | North East | Region | Table 9 | 1,000 |
| 112 | Mean hardness (mg/l CaCO3) | Northern Ireland | Region | Table 9 | 1,000 |
| 26% | Measure high porosity | Northern Ireland | Region | Table 9 | 1,000 |
| 36% | Weekly build-up | Northern Ireland | Region | Table 9 | 1,000 |
| 10% | Moved down a band after two clarifying washes | Northern Ireland | Region | Table 9 | 1,000 |
| 96 | Mean hardness (mg/l CaCO3) | North West | Region | Table 9 | 1,000 |
| 26% | Measure high porosity | North West | Region | Table 9 | 1,000 |
| 35% | Weekly build-up | North West | Region | Table 9 | 1,000 |
| 10% | Moved down a band after two clarifying washes | North West | Region | Table 9 | 1,000 |
| 84 | Mean hardness (mg/l CaCO3) | Wales | Region | Table 9 | 1,000 |
| 25% | Measure high porosity | Wales | Region | Table 9 | 1,000 |
| 33% | Weekly build-up | Wales | Region | Table 9 | 1,000 |
| 9% | Moved down a band after two clarifying washes | Wales | Region | Table 9 | 1,000 |
| 47 | Mean hardness (mg/l CaCO3) | Scotland | Region | Table 9 | 1,000 |
| 22% | Measure high porosity | Scotland | Region | Table 9 | 1,000 |
| 28% | Weekly build-up | Scotland | Region | Table 9 | 1,000 |
| 7% | Moved down a band after two clarifying washes | Scotland | Region | Table 9 | 1,000 |
| 38% | Low | England | Nation | Table 10 | 1,000 |
| 27% | Medium | England | Nation | Table 10 | 1,000 |
| 35% | High | England | Nation | Table 10 | 1,000 |
| 231 | Mean hardness (mg/l) | England | Nation | Table 10 | 1,000 |
| GBP 271 | Annual spend | England | Nation | Table 10 | 1,000 |
| GBP 86 | Abandoned per year | England | Nation | Table 10 | 1,000 |
| 12 | Products tried | England | Nation | Table 10 | 1,000 |
| 45% | Low | Northern Ireland | Nation | Table 10 | 1,000 |
| 29% | Medium | Northern Ireland | Nation | Table 10 | 1,000 |
| 26% | High | Northern Ireland | Nation | Table 10 | 1,000 |
| 112 | Mean hardness (mg/l) | Northern Ireland | Nation | Table 10 | 1,000 |
| GBP 246 | Annual spend | Northern Ireland | Nation | Table 10 | 1,000 |
| GBP 74 | Abandoned per year | Northern Ireland | Nation | Table 10 | 1,000 |
| 11 | Products tried | Northern Ireland | Nation | Table 10 | 1,000 |
| 46% | Low | Wales | Nation | Table 10 | 1,000 |
| 29% | Medium | Wales | Nation | Table 10 | 1,000 |
| 25% | High | Wales | Nation | Table 10 | 1,000 |
| 84 | Mean hardness (mg/l) | Wales | Nation | Table 10 | 1,000 |
| GBP 241 | Annual spend | Wales | Nation | Table 10 | 1,000 |
| GBP 71 | Abandoned per year | Wales | Nation | Table 10 | 1,000 |
| 11 | Products tried | Wales | Nation | Table 10 | 1,000 |
| 49% | Low | Scotland | Nation | Table 10 | 1,000 |
| 29% | Medium | Scotland | Nation | Table 10 | 1,000 |
| 22% | High | Scotland | Nation | Table 10 | 1,000 |
| 47 | Mean hardness (mg/l) | Scotland | Nation | Table 10 | 1,000 |
| GBP 234 | Annual spend | Scotland | Nation | Table 10 | 1,000 |
| GBP 64 | Abandoned per year | Scotland | Nation | Table 10 | 1,000 |
| 10 | Products tried | Scotland | Nation | Table 10 | 1,000 |
| 40% | Low | UK | Nation | Table 10 | 1,000 |
| 27% | Medium | UK | Nation | Table 10 | 1,000 |
| 33% | High | UK | Nation | Table 10 | 1,000 |
| 208 | Mean hardness (mg/l) | UK | Nation | Table 10 | 1,000 |
| GBP 264 | Annual spend | UK | Nation | Table 10 | 1,000 |
| GBP 81 | Abandoned per year | UK | Nation | Table 10 | 1,000 |
| 12 | Products tried | UK | Nation | Table 10 | 1,000 |
| GBP 212 | Mean annual spend | Low | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| GBP 178 | Median | Low | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| 6.4 | Products in rotation | Low | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| GBP 61 | Abandoned per year | Low | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| 28.8% | Waste as a share of spend | Low | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| 9 | Products tried before a working routine | Low | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| GBP 248 | Mean annual spend | Medium | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| GBP 205 | Median | Medium | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| 7.1 | Products in rotation | Medium | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| GBP 72 | Abandoned per year | Medium | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| 29.0% | Waste as a share of spend | Medium | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| 11 | Products tried before a working routine | Medium | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| GBP 341 | Mean annual spend | High | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| GBP 289 | Median | High | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| 9.8 | Products in rotation | High | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| GBP 118 | Abandoned per year | High | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| 34.6% | Waste as a share of spend | High | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| 16 | Products tried before a working routine | High | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| GBP 264 | Mean annual spend | UK average | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| GBP 216 | Median | UK average | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| 7.6 | Products in rotation | UK average | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| GBP 81 | Abandoned per year | UK average | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| 30.7% | Waste as a share of spend | UK average | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| 12 | Products tried before a working routine | UK average | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| GBP 212 | Year 1 | Low | Porosity band | Table 12 | 1,000 |
| GBP 636 | Year 3 cumulative | Low | Porosity band | Table 12 | 1,000 |
| GBP 1,060 | Year 5 cumulative | Low | Porosity band | Table 12 | 1,000 |
| GBP 305 | Of which abandoned | Low | Porosity band | Table 12 | 1,000 |
| GBP 248 | Year 1 | Medium | Porosity band | Table 12 | 1,000 |
| GBP 744 | Year 3 cumulative | Medium | Porosity band | Table 12 | 1,000 |
| GBP 1,240 | Year 5 cumulative | Medium | Porosity band | Table 12 | 1,000 |
| GBP 360 | Of which abandoned | Medium | Porosity band | Table 12 | 1,000 |
| +GBP 180 | Five-year gap against low porosity | Medium | Porosity band | Table 12 | 1,000 |
| GBP 341 | Year 1 | High | Porosity band | Table 12 | 1,000 |
| GBP 1,023 | Year 3 cumulative | High | Porosity band | Table 12 | 1,000 |
| GBP 1,705 | Year 5 cumulative | High | Porosity band | Table 12 | 1,000 |
| GBP 590 | Of which abandoned | High | Porosity band | Table 12 | 1,000 |
| +GBP 645 | Five-year gap against low porosity | High | Porosity band | Table 12 | 1,000 |
| 36% | Measure high porosity | Under GBP 20,000 | Household income | Table 13 | 890 |
| GBP 171 | Annual spend | Under GBP 20,000 | Household income | Table 13 | 890 |
| GBP 59 | Abandoned per year | Under GBP 20,000 | Household income | Table 13 | 890 |
| 34.5% | Waste as a share of spend | Under GBP 20,000 | Household income | Table 13 | 890 |
| 34% | Have ever tested porosity | Under GBP 20,000 | Household income | Table 13 | 890 |
| 8% | Have ever returned a haircare product | Under GBP 20,000 | Household income | Table 13 | 890 |
| 35% | Measure high porosity | GBP 20,000 to GBP 34,999 | Household income | Table 13 | 890 |
| GBP 221 | Annual spend | GBP 20,000 to GBP 34,999 | Household income | Table 13 | 890 |
| GBP 74 | Abandoned per year | GBP 20,000 to GBP 34,999 | Household income | Table 13 | 890 |
| 33.5% | Waste as a share of spend | GBP 20,000 to GBP 34,999 | Household income | Table 13 | 890 |
| 36% | Have ever tested porosity | GBP 20,000 to GBP 34,999 | Household income | Table 13 | 890 |
| 11% | Have ever returned a haircare product | GBP 20,000 to GBP 34,999 | Household income | Table 13 | 890 |
| 33% | Measure high porosity | GBP 35,000 to GBP 54,999 | Household income | Table 13 | 890 |
| GBP 276 | Annual spend | GBP 35,000 to GBP 54,999 | Household income | Table 13 | 890 |
| GBP 86 | Abandoned per year | GBP 35,000 to GBP 54,999 | Household income | Table 13 | 890 |
| 31.2% | Waste as a share of spend | GBP 35,000 to GBP 54,999 | Household income | Table 13 | 890 |
| 39% | Have ever tested porosity | GBP 35,000 to GBP 54,999 | Household income | Table 13 | 890 |
| 14% | Have ever returned a haircare product | GBP 35,000 to GBP 54,999 | Household income | Table 13 | 890 |
| 31% | Measure high porosity | GBP 55,000 to GBP 79,999 | Household income | Table 13 | 890 |
| GBP 329 | Annual spend | GBP 55,000 to GBP 79,999 | Household income | Table 13 | 890 |
| GBP 94 | Abandoned per year | GBP 55,000 to GBP 79,999 | Household income | Table 13 | 890 |
| 28.6% | Waste as a share of spend | GBP 55,000 to GBP 79,999 | Household income | Table 13 | 890 |
| 43% | Have ever tested porosity | GBP 55,000 to GBP 79,999 | Household income | Table 13 | 890 |
| 17% | Have ever returned a haircare product | GBP 55,000 to GBP 79,999 | Household income | Table 13 | 890 |
| 29% | Measure high porosity | GBP 80,000 and over | Household income | Table 13 | 890 |
| GBP 412 | Annual spend | GBP 80,000 and over | Household income | Table 13 | 890 |
| GBP 108 | Abandoned per year | GBP 80,000 and over | Household income | Table 13 | 890 |
| 26.2% | Waste as a share of spend | GBP 80,000 and over | Household income | Table 13 | 890 |
| 47% | Have ever tested porosity | GBP 80,000 and over | Household income | Table 13 | 890 |
| 19% | Have ever returned a haircare product | GBP 80,000 and over | Household income | Table 13 | 890 |
| 33% | Measure high porosity | All | Household income | Table 13 | 890 |
| GBP 264 | Annual spend | All | Household income | Table 13 | 890 |
| GBP 81 | Abandoned per year | All | Household income | Table 13 | 890 |
| 30.7% | Waste as a share of spend | All | Household income | Table 13 | 890 |
| 39% | Have ever tested porosity | All | Household income | Table 13 | 890 |
| 13% | Have ever returned a haircare product | All | Household income | Table 13 | 890 |
| 218 | Base | Hairdresser or stylist | Source of label | Table 14 | 512 |
| 57% | Mismatch on retest | Hairdresser or stylist | Source of label | Table 14 | 512 |
| 66% | Direction of error (labelled too high) | Hairdresser or stylist | Source of label | Table 14 | 512 |
| 4.4 | Products bought on that advice | Hairdresser or stylist | Source of label | Table 14 | 512 |
| 2.6 | Products abandoned | Hairdresser or stylist | Source of label | Table 14 | 512 |
| 147 | Base | Brand or retailer quiz | Source of label | Table 14 | 512 |
| 68% | Mismatch on retest | Brand or retailer quiz | Source of label | Table 14 | 512 |
| 79% | Direction of error (labelled too high) | Brand or retailer quiz | Source of label | Table 14 | 512 |
| 4.2 | Products bought on that advice | Brand or retailer quiz | Source of label | Table 14 | 512 |
| 3.0 | Products abandoned | Brand or retailer quiz | Source of label | Table 14 | 512 |
| 89 | Base | Shop assistant or consultant | Source of label | Table 14 | 512 |
| 71% | Mismatch on retest | Shop assistant or consultant | Source of label | Table 14 | 512 |
| 74% | Direction of error (labelled too high) | Shop assistant or consultant | Source of label | Table 14 | 512 |
| 3.6 | Products bought on that advice | Shop assistant or consultant | Source of label | Table 14 | 512 |
| 2.6 | Products abandoned | Shop assistant or consultant | Source of label | Table 14 | 512 |
| 58 | Base | Friend or family member | Source of label | Table 14 | 512 |
| 64% | Mismatch on retest | Friend or family member | Source of label | Table 14 | 512 |
| 62% | Direction of error (labelled too high) | Friend or family member | Source of label | Table 14 | 512 |
| 3.1 | Products bought on that advice | Friend or family member | Source of label | Table 14 | 512 |
| 2.2 | Products abandoned | Friend or family member | Source of label | Table 14 | 512 |
| 512 | Base | All | Source of label | Table 14 | 512 |
| 61% | Mismatch on retest | All | Source of label | Table 14 | 512 |
| 71% | Direction of error (labelled too high) | All | Source of label | Table 14 | 512 |
| 4.1 | Products bought on that advice | All | Source of label | Table 14 | 512 |
| 2.7 | Products abandoned | All | Source of label | Table 14 | 512 |
| 51% | Measured low | Guessed low | Guessed band | Table 15 | 1,000 |
| 32% | Measured medium | Guessed low | Guessed band | Table 15 | 1,000 |
| 17% | Measured high | Guessed low | Guessed band | Table 15 | 1,000 |
| 51% | Guessed correctly | Guessed low | Guessed band | Table 15 | 1,000 |
| 34% | Measured low | Guessed medium | Guessed band | Table 15 | 1,000 |
| 27% | Measured medium | Guessed medium | Guessed band | Table 15 | 1,000 |
| 39% | Measured high | Guessed medium | Guessed band | Table 15 | 1,000 |
| 27% | Guessed correctly | Guessed medium | Guessed band | Table 15 | 1,000 |
| 19% | Measured low | Guessed high | Guessed band | Table 15 | 1,000 |
| 29% | Measured medium | Guessed high | Guessed band | Table 15 | 1,000 |
| 52% | Measured high | Guessed high | Guessed band | Table 15 | 1,000 |
| 52% | Guessed correctly | Guessed high | Guessed band | Table 15 | 1,000 |
| 46% | Guessed correctly | All respondents | Guessed band | Table 15 | 1,000 |
| 41% | Share who agree | Porosity is fixed for life | Belief | Table 16 | 1,000 |
| 37% | Share who agree | Low porosity means healthy hair | Belief | Table 16 | 1,000 |
| 44% | Share who agree | The float test is reliable | Belief | Table 16 | 1,000 |
| 33% | Share who agree | Curly hair is automatically high porosity | Belief | Table 16 | 1,000 |
| 52% | Share who agree | Protein repairs all damaged hair | Belief | Table 16 | 1,000 |
| 29% | Share who agree | A product can change your porosity | Belief | Table 16 | 1,000 |
| 58% | Share who agree | Porosity-labelled products work better | Belief | Table 16 | 1,000 |
| 3h 40m | Low porosity | Median air-dry time | Porosity band | Table 17 | 400 |
| 2h 25m | UK average | Median air-dry time | Porosity band | Table 17 | 400 |
| 62% | Low porosity | Product build-up within four washes | Porosity band | Table 17 | 400 |
| 44% | UK average | Product build-up within four washes | Porosity band | Table 17 | 400 |
| 29% | Low porosity | Frizz within 30 minutes of humid air | Porosity band | Table 17 | 400 |
| 48% | UK average | Frizz within 30 minutes of humid air | Porosity band | Table 17 | 400 |
| 23% | Low porosity | Uses a heavy butter or oil daily | Porosity band | Table 17 | 400 |
| 27% | UK average | Uses a heavy butter or oil daily | Porosity band | Table 17 | 400 |
| 34% | Low porosity | Used a protein treatment in the last 90 days | Porosity band | Table 17 | 400 |
| 38% | UK average | Used a protein treatment in the last 90 days | Porosity band | Table 17 | 400 |
| 47% | Low porosity | Rated that protein treatment negatively | Porosity band | Table 17 | 400 |
| 29% | UK average | Rated that protein treatment negatively | Porosity band | Table 17 | 400 |
| 51% | Low porosity | Bought a repair or bond-building product in the last 12 months | Porosity band | Table 17 | 400 |
| 46% | UK average | Bought a repair or bond-building product in the last 12 months | Porosity band | Table 17 | 400 |
| GBP 212 | Low porosity | Annual haircare spend | Porosity band | Table 17 | 400 |
| GBP 264 | UK average | Annual haircare spend | Porosity band | Table 17 | 400 |
| 28.8% | Low porosity | Waste as a share of spend | Porosity band | Table 17 | 400 |
| 30.7% | UK average | Waste as a share of spend | Porosity band | Table 17 | 400 |
| 1h 15m | High porosity | Median air-dry time | Porosity band | Table 18 | 330 |
| 2h 25m | UK average | Median air-dry time | Porosity band | Table 18 | 330 |
| 68% | High porosity | "Products stop working after a few weeks" | Porosity band | Table 18 | 330 |
| 49% | UK average | "Products stop working after a few weeks" | Porosity band | Table 18 | 330 |
| 71% | High porosity | Frizz within 30 minutes of humid air | Porosity band | Table 18 | 330 |
| 48% | UK average | Frizz within 30 minutes of humid air | Porosity band | Table 18 | 330 |
| 58% | High porosity | Chemically straightened or coloured in the last 3 years | Porosity band | Table 18 | 330 |
| 42% | UK average | Chemically straightened or coloured in the last 3 years | Porosity band | Table 18 | 330 |
| 21% | High porosity | Product build-up within four washes | Porosity band | Table 18 | 330 |
| 44% | UK average | Product build-up within four washes | Porosity band | Table 18 | 330 |
| 39% | High porosity | Uses a heavy butter or oil daily | Porosity band | Table 18 | 330 |
| 27% | UK average | Uses a heavy butter or oil daily | Porosity band | Table 18 | 330 |
| 63% | High porosity | Bought a repair or bond-building product in the last 12 months | Porosity band | Table 18 | 330 |
| 46% | UK average | Bought a repair or bond-building product in the last 12 months | Porosity band | Table 18 | 330 |
| GBP 341 | High porosity | Annual haircare spend | Porosity band | Table 18 | 330 |
| GBP 264 | UK average | Annual haircare spend | Porosity band | Table 18 | 330 |
| 34.6% | High porosity | Waste as a share of spend | Porosity band | Table 18 | 330 |
| 30.7% | UK average | Waste as a share of spend | Porosity band | Table 18 | 330 |
| 27% | Medium porosity | Share of UK women | Porosity band | Table 19 | 270 |
| 27% | Medium porosity | Guessed their band correctly | Porosity band | Table 19 | 270 |
| 46% | UK average | Guessed their band correctly | Porosity band | Table 19 | 270 |
| 2h 10m | Medium porosity | Median air-dry time | Porosity band | Table 19 | 270 |
| 2h 25m | UK average | Median air-dry time | Porosity band | Table 19 | 270 |
| 38% | Medium porosity | Build-up within four washes | Porosity band | Table 19 | 270 |
| 44% | UK average | Build-up within four washes | Porosity band | Table 19 | 270 |
| 44% | Medium porosity | Frizz within 30 minutes | Porosity band | Table 19 | 270 |
| 48% | UK average | Frizz within 30 minutes | Porosity band | Table 19 | 270 |
| 7.1 | Medium porosity | Products in rotation | Porosity band | Table 19 | 270 |
| 7.6 | UK average | Products in rotation | Porosity band | Table 19 | 270 |
| GBP 248 | Medium porosity | Annual spend | Porosity band | Table 19 | 270 |
| GBP 264 | UK average | Annual spend | Porosity band | Table 19 | 270 |
| GBP 72 | Medium porosity | Abandoned per year | Porosity band | Table 19 | 270 |
| GBP 81 | UK average | Abandoned per year | Porosity band | Table 19 | 270 |
| 4.6% | Medium porosity | Share of the labelled product range | Porosity band | Table 19 | 270 |
| 34 | Intervention | 0 | Trial arm | Table 20 | 312 intervention, 104 control |
| 34 | Control | 0 | Trial arm | Table 20 | 312 intervention, 104 control |
| 0 | Gap | 0 | Trial arm | Table 20 | 312 intervention, 104 control |
| 41 | Intervention | 7 | Trial arm | Table 20 | 312 intervention, 104 control |
| 34 | Control | 7 | Trial arm | Table 20 | 312 intervention, 104 control |
| +7 | Gap | 7 | Trial arm | Table 20 | 312 intervention, 104 control |
| 49 | Intervention | 14 | Trial arm | Table 20 | 312 intervention, 104 control |
| 35 | Control | 14 | Trial arm | Table 20 | 312 intervention, 104 control |
| +14 | Gap | 14 | Trial arm | Table 20 | 312 intervention, 104 control |
| 55 | Intervention | 21 | Trial arm | Table 20 | 312 intervention, 104 control |
| 35 | Control | 21 | Trial arm | Table 20 | 312 intervention, 104 control |
| +20 | Gap | 21 | Trial arm | Table 20 | 312 intervention, 104 control |
| 62 | Intervention | 30 | Trial arm | Table 20 | 312 intervention, 104 control |
| 36 | Control | 30 | Trial arm | Table 20 | 312 intervention, 104 control |
| +26 | Gap | 30 | Trial arm | Table 20 | 312 intervention, 104 control |
| 69 | Intervention | 45 | Trial arm | Table 20 | 312 intervention, 104 control |
| 36 | Control | 45 | Trial arm | Table 20 | 312 intervention, 104 control |
| +33 | Gap | 45 | Trial arm | Table 20 | 312 intervention, 104 control |
| 74 | Intervention | 60 | Trial arm | Table 20 | 312 intervention, 104 control |
| 37 | Control | 60 | Trial arm | Table 20 | 312 intervention, 104 control |
| +37 | Gap | 60 | Trial arm | Table 20 | 312 intervention, 104 control |
| 77 | Intervention | 75 | Trial arm | Table 20 | 312 intervention, 104 control |
| 37 | Control | 75 | Trial arm | Table 20 | 312 intervention, 104 control |
| +40 | Gap | 75 | Trial arm | Table 20 | 312 intervention, 104 control |
| 79 | Intervention | 90 | Trial arm | Table 20 | 312 intervention, 104 control |
| 37 | Control | 90 | Trial arm | Table 20 | 312 intervention, 104 control |
| +42 | Gap | 90 | Trial arm | Table 20 | 312 intervention, 104 control |
| 61 | Day-84 score | A | Trial arm | Table 21 | 524, four arms of 131 |
| GBP 41.20 | Mean 12-week basket | A | Trial arm | Table 21 | 524, four arms of 131 |
| GBP 1.53 | Cost per point above baseline | A | Trial arm | Table 21 | 524, four arms of 131 |
| 71 | Day-84 score | B | Trial arm | Table 21 | 524, four arms of 131 |
| GBP 49.80 | Mean 12-week basket | B | Trial arm | Table 21 | 524, four arms of 131 |
| GBP 1.35 | Cost per point above baseline | B | Trial arm | Table 21 | 524, four arms of 131 |
| 76 | Day-84 score | C | Trial arm | Table 21 | 524, four arms of 131 |
| GBP 38.90 | Mean 12-week basket | C | Trial arm | Table 21 | 524, four arms of 131 |
| GBP 0.93 | Cost per point above baseline | C | Trial arm | Table 21 | 524, four arms of 131 |
| 79 | Day-84 score | D | Trial arm | Table 21 | 524, four arms of 131 |
| GBP 57.40 | Mean 12-week basket | D | Trial arm | Table 21 | 524, four arms of 131 |
| GBP 1.28 | Cost per point above baseline | D | Trial arm | Table 21 | 524, four arms of 131 |
| +19 | Points gained at day 84 | 1 | Change | Table 22 | 524 |
| +14 | Points gained at day 84 | 2 | Change | Table 22 | 524 |
| +11 | Points gained at day 84 | 3 | Change | Table 22 | 524 |
| +11 | Points gained at day 84 | 4 | Change | Table 22 | 524 |
| +9 | Points gained at day 84 | 5 | Change | Table 22 | 524 |
| +8 | Points gained at day 84 | 6 | Change | Table 22 | 524 |
| +8 | Points gained at day 84 | 7 | Change | Table 22 | 524 |
| +7 | Points gained at day 84 | 8 | Change | Table 22 | 524 |
| +6 | Points gained at day 84 | 9 | Change | Table 22 | 524 |
| +3 | Points gained at day 84 | 10 | Change | Table 22 | 524 |
| +2 | Points gained at day 84 | 11 | Change | Table 22 | 524 |
| 33% | February | Measure high porosity | Season | Table 23 | 612 |
| 37% | August | Measure high porosity | Season | Table 23 | 612 |
| +4 pts | Movement | Measure high porosity | Season | Table 23 | 612 |
| 27% | February | Measure medium porosity | Season | Table 23 | 612 |
| 26% | August | Measure medium porosity | Season | Table 23 | 612 |
| -1 pt | Movement | Measure medium porosity | Season | Table 23 | 612 |
| 40% | February | Measure low porosity | Season | Table 23 | 612 |
| 37% | August | Measure low porosity | Season | Table 23 | 612 |
| -3 pts | Movement | Measure low porosity | Season | Table 23 | 612 |
| 2h 25m | February | Median air-dry time | Season | Table 23 | 612 |
| 1h 50m | August | Median air-dry time | Season | Table 23 | 612 |
| -35 min | Movement | Median air-dry time | Season | Table 23 | 612 |
| 44% | February | Build-up within four washes | Season | Table 23 | 612 |
| 39% | August | Build-up within four washes | Season | Table 23 | 612 |
| -5 pts | Movement | Build-up within four washes | Season | Table 23 | 612 |
| 48% | February | Frizz within 30 minutes of humid air | Season | Table 23 | 612 |
| 63% | August | Frizz within 30 minutes of humid air | Season | Table 23 | 612 |
| +15 pts | Movement | Frizz within 30 minutes of humid air | Season | Table 23 | 612 |
| 7.6 | February | Products in rotation | Season | Table 23 | 612 |
| 8.4 | August | Products in rotation | Season | Table 23 | 612 |
| +0.8 | Movement | Products in rotation | Season | Table 23 | 612 |
| GBP 22 | February | Monthly haircare spend | Season | Table 23 | 612 |
| GBP 24 | August | Monthly haircare spend | Season | Table 23 | 612 |
| +GBP 2 | Movement | Monthly haircare spend | Season | Table 23 | 612 |
| 58% | 2024 | Heard the term | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| 72% | 2026 | Heard the term | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| +14 pts | Movement | Heard the term | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| 31% | 2024 | Ever tested | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| 39% | 2026 | Ever tested | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| +8 pts | Movement | Ever tested | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| 14% | 2024 | Confident they know their own | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| 19% | 2026 | Confident they know their own | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| +5 pts | Movement | Confident they know their own | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| 51% | 2024 | Used the float test, among testers | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| 43% | 2026 | Used the float test, among testers | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| -8 pts | Movement | Used the float test, among testers | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| 27% | 2024 | Bought a porosity-labelled product in the last 12 months | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| 44% | 2026 | Bought a porosity-labelled product in the last 12 months | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| +17 pts | Movement | Bought a porosity-labelled product in the last 12 months | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| GBP 229 | 2024 | Annual spend | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| GBP 264 | 2026 | Annual spend | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| +GBP 35 | Movement | Annual spend | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| GBP 71 | 2024 | Abandoned per year | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| GBP 81 | 2026 | Abandoned per year | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| +GBP 10 | Movement | Abandoned per year | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| 64% | 2024 | Mismatch rate on retest | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| 61% | 2026 | Mismatch rate on retest | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| -3 pts | Movement | Mismatch rate on retest | Year | Table 24 | 604 in 2024, 1,000 in 2026 |
| 72% | 2026 actual | Heard the term | Year | Table 25 | 1,000 in 2026 |
| 81% | 2028 projected | Heard the term | Year | Table 25 | 1,000 in 2026 |
| 89% | 2031 projected | Heard the term | Year | Table 25 | 1,000 in 2026 |
| 39% | 2026 actual | Ever tested | Year | Table 25 | 1,000 in 2026 |
| 47% | 2028 projected | Ever tested | Year | Table 25 | 1,000 in 2026 |
| 58% | 2031 projected | Ever tested | Year | Table 25 | 1,000 in 2026 |
| 19% | 2026 actual | Confident they know their own | Year | Table 25 | 1,000 in 2026 |
| 26% | 2028 projected | Confident they know their own | Year | Table 25 | 1,000 in 2026 |
| 35% | 2031 projected | Confident they know their own | Year | Table 25 | 1,000 in 2026 |
| 61% | 2026 actual | Mismatch rate on retest | Year | Table 25 | 1,000 in 2026 |
| 55% | 2028 projected | Mismatch rate on retest | Year | Table 25 | 1,000 in 2026 |
| 44% | 2031 projected | Mismatch rate on retest | Year | Table 25 | 1,000 in 2026 |
| GBP 264 | 2026 actual | Annual spend | Year | Table 25 | 1,000 in 2026 |
| GBP 291 | 2028 projected | Annual spend | Year | Table 25 | 1,000 in 2026 |
| GBP 328 | 2031 projected | Annual spend | Year | Table 25 | 1,000 in 2026 |
| GBP 81 | 2026 actual | Abandoned per year | Year | Table 25 | 1,000 in 2026 |
| GBP 79 | 2028 projected | Abandoned per year | Year | Table 25 | 1,000 in 2026 |
| GBP 68 | 2031 projected | Abandoned per year | Year | Table 25 | 1,000 in 2026 |
| 78% | 2026 figure | Working without a reliable porosity reading | Finding | Table 26 | 1,000 |
| 34 / 31 / 35 | 2026 figure | Porosity split at 3B hair | Finding | Table 26 | 1,000 |
| 11% v 27% | 2026 figure | Explained variance, curl pattern against porosity | Finding | Table 26 | 1,000 |
| 265 mg/l | 2026 figure | Hardness gap, East of England to Scotland | Finding | Table 26 | 1,000 |
| 4.6% | 2026 figure | Medium porosity share of the labelled range | Finding | Table 26 | 1,000 |
| +42 points | 2026 figure | 90-day satisfaction gap after correction | Finding | Table 26 | 1,000 |
| 34.5% | 2026 figure | Waste as a share of spend, lowest income band | Finding | Table 26 | 1,000 |
| +3 points at +48% cost | 2026 figure | Porosity labelling advantage | Finding | Table 26 | 1,000 |
| 61% | Have never tested their own porosity | All UK women | National | Table 1 | 1,000 |
| 40% | UK national panel | Low porosity | Porosity band | Table 3 | 1,000 panel, 8,847 Curl Identifier |
| GBP 341 | Mean annual spend | High porosity | Porosity band | Table 11 | 400 low, 270 medium, 330 high |
| 59% | High | 4C, the tightest coil pattern | Curl pattern | Table 5 | 1,000 |
Every row is in the page source whether or not JavaScript runs, which is what makes each figure individually addressable. Source: Zenvy Beauty Research, 2026 edition.
Frequently asked questions[#]
What percentage of people have low porosity hair?
40% of UK women have low-porosity hair in 2026, against 27% medium and 33% high, measured on a six-signal protocol across a panel of 1,000. It is the largest of the three bands, and this is the first national porosity distribution published for the UK.
How common is high porosity hair?
33% of UK women measure high porosity in 2026. It rises with age, from 21% at 18-24 to 46% at 55-65, and with curl pattern, from 17% of 2A hair to 59% of 4C hair. High-porosity women spend £341 a year on haircare against £212 for low porosity.
How many people have medium porosity hair?
27% of UK women have medium-porosity hair in 2026, and only 27% of them guess it correctly before testing. Just 4.6% of the labelled UK product range is aimed at them, which makes it the largest group in Britain with no category built for it.
Is the float test for hair porosity accurate?
43% of everyone who has tested their porosity in the UK used the float test in 2026, and it is the most confounded of the six signals we measured. Product residue, strand thickness and surface tension all move the result without the cuticle changing at all.
How do I test my hair porosity properly?
Use six signals, not one. The Zenvy 2026 protocol combines strand float, spray absorption, air-dry time, washes to build-up, slip-test roughness and time to frizz in humid air. Run against that composite, 61% of UK women who had been given a porosity label by someone else were reclassified.
How long should low porosity hair take to dry?
3 hours 40 minutes is the median UK air-dry time for low-porosity hair in 2026, against 1 hour 15 minutes for high porosity. That two and a half hour gap is the widest single-signal separation anywhere in our dataset, which makes dry time one of the most useful free tests available.
Does hard water affect hair porosity?
43% of women in England’s hardest-water regions measure high porosity in 2026, against 22% in Scotland, where mean hardness is 47 mg/l of calcium carbonate. Hard water does not restructure the cuticle, but its mineral deposit produces almost every signal a porosity test reads as high porosity.
Will a clarifying wash change my porosity result?
31% of UK women in very hard water areas moved down a porosity band after two clarifying washes over a fortnight in 2026. In soft water areas the same protocol moved 9%. If mineral deposit is driving the reading rather than cuticle damage, clarifying changes the answer inside a fortnight.
Does curly hair have high porosity?
Not automatically. High porosity runs from 17% of 2A hair to 59% of 4C hair in 2026, so even at the tightest coil pattern more than two women in five are not high porosity. Curl pattern narrows the odds. It does not decide the answer.
Can hair porosity change?
Yes. 58% of UK women measuring high porosity in 2026 had chemically straightened or coloured within the previous three years, against 31% of those measuring low porosity. Porosity is a reading you take rather than a label you are, and readings expire.
How often should I retest my hair porosity?
68% of UK women whose porosity label was given more than five years ago now measure a different band in 2026. Retest after any colour service, after any chemical service, and otherwise every two years. A reading taken at 26 is not one you can still buy to at 41.
How much more does high porosity hair cost to look after?
£341 a year in the UK in 2026, against £212 for low porosity. High-porosity women also abandon £118 of product a year against £61, and buy a median of 16 products before finding a routine that works, against 9 for low porosity.
How much money do British women waste on haircare?
£81 a year each, on products bought and then abandoned, in 2026. The cost is regressive. Households under £20,000 waste 34.5% of what they spend on hair, against 26.2% in households over £80,000, so the band least able to absorb it gets the worst return on every pound.
Do porosity-labelled products work better?
By three points on a hundred-point scale, at a 48% higher price. In Zenvy’s 2026 twelve-week trial, unlabelled products chosen by weight to match density scored 76 at day 84, against 79 for porosity-labelled products. That gap sits inside the plus or minus 4.1 margin of error.
What matters more, porosity or curl type?
Porosity, by a wide margin. In Zenvy’s 2026 trial porosity explained 27% of whether a product worked and curl pattern explained 11%, which makes curl pattern the weakest of the three variables. Density and strand width together explained 19%, and all three combined explained 41%.
What is hair density and how is it different from porosity?
Density is how many strands grow per square centimetre of scalp. Porosity is how open the cuticle sits. Only 14% of UK women can describe their own density in 2026, against 72% who have heard of porosity, and 47% are using a product weight that does not match their hair.
What is strand width?
Strand width is the thickness of one individual hair. Britain splits fine 31%, medium 44% and coarse 25% in 2026, and only 19% of UK women can place their own. It decides product weight more directly than curl pattern does, which is why matching product weight to it is the highest-scoring change in our 2026 trial.
How long does it take to see a difference from a porosity-matched routine?
UK women who switched to a porosity-matched routine went from 34 out of 100 at baseline to 79 out of 100 at day 90 in 2026, while a control group who changed nothing moved from 34 to 37. The study ran across 416 women over three months.
Why do my products stop working after a few weeks?
68% of high-porosity UK women reported exactly this in 2026. High-porosity hair loses what it is given, so the deficit reasserts itself; and the sealing products it needs build up if the wash routine does not keep pace, which reads as the product failing when it is the schedule that has slipped.
Is low porosity hair healthy hair?
Low porosity is a description of cuticle closure, not a health grade. 62% of low-porosity UK women see product build-up within four washes in 2026, which is a behaviour rather than a condition. Heavily coated hair reads low on every behavioural signal regardless of its structural state.
Can I have low porosity hair and still have damage?
Yes. Heavily coated hair reads low on every behavioural signal in the protocol whatever its structural condition. 51% of low-porosity UK women bought a repair or bond-building product in 2026, a category built for the opposite problem. A clarifying wash before retesting is how you tell the two apart.
Does protein help low porosity hair?
Usually not. 34% of low-porosity UK women used a protein treatment in the previous 90 days in 2026, and 47% of them described the result as stiff, straw-like or worse than before. Protein is a fit question rather than a quality question.
What is the best thing I can do for my hair?
Match product weight to your strand width and density. It moved satisfaction 19 points in twelve weeks in Zenvy’s 2026 trial, more than any other change measured, and it costs nothing. It is a change in how you choose rather than in what you spend.
Does a satin pillowcase actually do anything?
Eight points of satisfaction over twelve weeks in Zenvy’s 2026 trial, for £8 to £16 once. That places it seventh of the eleven changes we measured, above a porosity-labelled product line at three points and above a bond-building treatment at two.
Are bond-building treatments worth it?
They moved satisfaction two points over twelve weeks in Zenvy’s 2026 trial, at £28 to £42 per treatment. Two points sits inside the plus or minus 4.1 margin of error, so the effect is directional rather than proven, and the treatment ranked last of the eleven changes we measured.
Why does my hair porosity seem different in summer?
Because it reads differently. Measured high porosity rose from 33% in February to 37% in August across the same 612 UK women in 2026, driven by temperature and dew point rather than by any change to the cuticle. Roughly one in nine high-porosity summer readings comes back as medium in winter.
Which UK region has the most high porosity hair?
The East of England, at 43% in 2026, followed by London at 41% and the South East at 39%. Scotland is lowest at 22%. The ranking tracks mean water hardness across the twelve UK regions with a rank correlation of 0.94.
Did my hairdresser get my porosity wrong?
Possibly. 57% of UK women given a porosity label by a hairdresser were reclassified on a six-signal retest in 2026, and 66% of those errors were a label of high porosity on hair measuring medium or low. There is no standard UK protocol for a stylist to follow, which is a training gap rather than a competence one.
How many products do British women try before finding a routine that works?
Twelve on average in 2026, rising to sixteen for high-porosity hair and falling to nine for low porosity. Medium-porosity women sit at eleven. Women who have never tested their porosity try three more products than the women who have, and almost all of that searching happens before anybody has measured anything.
Where can I get the data behind this report?
The full anonymised dataset is available on request to emma@zenvy-beauty.com. Every table on this page can be copied as tab-separated text or downloaded as a CSV using the buttons beneath it, and every figure is indexed back to its source table in the Porosity Data Index.
