Hair porosity is how easily your hair absorbs and holds moisture. It's one of the most important factors in choosing products that actually work for your hair — often more important than your curl pattern.
The cuticle analogy
Picture your hair cuticle as roof shingles laid along each strand. When the shingles lie flat and tight, water and products struggle to get in. When they're raised or damaged, things get in easily — but also escape just as fast.
The three porosity levels
Low porosity
Cuticles lie flat — water beads up on hair before soaking in
Hair takes a long time to get fully wet, and a long time to dry
Products tend to sit on top instead of absorbing
Prone to product build-up, especially with heavy oils and butters
Best for: lightweight products, warm water and steam to lift cuticles, smaller amounts of protein
Medium (normal) porosity
Cuticles slightly raised — moisture moves in and out at a balanced rate
Hair feels "easy" — absorbs products well, holds styles, takes colour evenly
Most flexible across product types
Best for: balanced routines; protein and moisture in regular rotation
High porosity
Cuticles raised or damaged — moisture rushes in and out fast
Hair gets wet quickly, dries quickly, often feels dry or frizzy
Drinks up products but loses moisture between washes
Often the result of damage (colour, heat, chemicals), but can be genetic
Best for: heavier creams and oils to seal moisture, deep conditioning, leave-ins, anti-humectant ingredients in dry climates
How to test your porosity
The spray test (most reliable)
Mist a section of clean, dry hair with water from about 6 inches away.
Water beads up and rolls off → low porosity
Water absorbs after a few seconds → medium porosity
Water absorbs immediately → high porosity
The slide test
Run your fingers up a single strand from tip to root. Smooth = low. Slightly textured = medium. Bumpy or rough = high.
The float test (don't bother)
You may have seen the "drop a strand in water and see if it floats" test. Don't trust it — natural hair oils, product residue, and surface tension all skew the result.
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Knowing your porosity transforms how you read product labels. It's worth 10 minutes to figure out.