Free tool · 2 minutes

Hair Porosity Test: Low, Medium or High?

Eight questions, including the float test and the finger-slide test, and you get your porosity with a wash-day routine, the ingredients that work on it, and the ones that will sit on top doing nothing.

Two people can buy the same conditioner and get opposite results. Porosity is why. Porosity means how open the outer layer of your hair is. It decides how fast water gets in, and how fast it leaves. Guess wrong and your hair feels greasy and dry at once. Or it drinks a whole bottle of product and still frizzes by lunch.

This test asks eight questions. It includes the float test and the slide test, and it weighs them together instead of trusting one. You get low, medium or high porosity. You also get a wash-day routine, the ingredients to reach for, and the ones to skip.

What hair porosity actually is

Every strand has an outer layer called the cuticle. It is made of tiny scales that overlap like roof tiles. When those scales lie flat and tight, water struggles to get past them. That is low porosity. When they are lifted or damaged, water moves in and out freely. That is high porosity. Medium sits between the two and is the easiest to live with.

Part of your porosity comes from your genes. Part of it you earn. Some people are born with a tightly packed cuticle. Most people move toward high porosity over time. Bleach, box dye, flat irons and hot water all push it that way. That is why the same head of hair can be low porosity at the roots and high porosity at the ends, where the damage has built up.

The three tests, done properly

The float test. Take a strand that has shed naturally, drop it in a glass of room-temperature water, and wait four minutes. Floating means low porosity, mid-glass means medium, and sinking means high. The catch is that it only works on clean hair. Any product, oil or dry shampoo coats the strand and makes it float. That is how so many people decide they are low porosity when they are not.

The spray test. Mist plain water onto a dry section. Water that beads and rolls off is meeting a closed cuticle. Water that vanishes on contact is being pulled straight in. This one is quicker than the float test and harder to get wrong.

The slide test. Hold a strand at the end and run your fingers up toward your scalp. Smooth and slippery is a flat cuticle. Bumpy, rough or catchy means the scales are raised. Do this on the mid-lengths, not the very ends, which are damaged on almost everyone.

Two drying clues matter just as much. One is how long your hair takes to air dry. The other is how it acts in humid air. Hair that stays wet for hours is holding water behind a closed cuticle. Hair that dries in forty minutes and frizzes right away is holding nothing.

How to treat each porosity type

Low porosity. Your problem is getting moisture in, not keeping it. Warmth is the key: apply your mask to damp hair, add a cap, and give it ten minutes. Keep products light and watery. Use a clarifying shampoo often so build-up does not block them. Go easy on protein, since low porosity hair rarely needs it.

Medium porosity. Switch between protein and moisture masks. Condition every wash and use heat protectant. This type turns into high porosity more often than any other, so your job is upkeep, not repair.

High porosity. Your problem is keeping moisture in. Layer it: liquid first, then an oil to seal, then a cream on top. Use cooler rinses, sleep on satin, and pair every protein treatment with a moisturizing mask so your hair does not go brittle.

Three myths worth dropping

“The float test is the final word.” It is one clue. Clean hair, room-temperature water and four minutes give you a decent signal; anything else gives you a coin flip. That is why this test weighs eight answers instead of one.

“Low porosity means healthy hair.” Porosity is not a grade. Low porosity hair can be perfectly healthy and still look dull because products are sitting on the surface.

“You can change your porosity for good.” You can close a raised cuticle for a few days with cool rinses and protein. You can also stop more damage. But you cannot rebuild a cuticle that bleach has worn away. Those ends have to grow out.

Frequently Asked Questions

What is a hair porosity test? −

It is a set of checks that show how easily your hair takes in water and how long it holds it. The float test, the spray test and the finger-slide test are the common ones, and together they place you at low, medium or high porosity.

How do I test hair porosity at home? −

Drop one clean shed strand into a glass of room-temperature water and wait four minutes. Floating means low porosity, mid-glass means medium, sinking means high. Back it up by spraying water on dry hair and watching whether it beads or absorbs.

Is the float test accurate? −

Only as one clue among several. Product, oil or dry shampoo on the strand makes it float regardless of porosity, which is the most common reason people get a wrong result. Use clean hair and combine it with the spray and slide tests.

What does low porosity hair need? −

Warmth and light products. Apply conditioner to damp hair with a cap for ten minutes, use watery leave-ins rather than heavy butters, clarify every few weeks to clear build-up, and keep protein treatments occasional.

What does high porosity hair need? −

Sealing. Apply liquid, then oil, then cream on damp hair, rinse with cool water, deep condition weekly and use protein often, always followed by a moisturizing mask so the hair does not turn brittle.

Can hair porosity change? −

Yes, in one direction easily. Bleach, box dye and heat raise the cuticle and push hair toward high porosity. You can smooth a raised cuticle for a while with cool rinses and protein, but damaged ends only truly leave when they are cut off.

Keep going: once you know your porosity, pick a cut that works with it in our thin hair guide or coily hairstyles, and find your color season with the color analysis quiz.