Summary

Your hair type (curl pattern and strand thickness) and porosity determine how your hair absorbs moisture and responds to products and heat. Here is how to test both at home.

Most "this product did nothing" stories come down to a mismatch: the product was fine, but it wasn't made for that hair. Two simple traits explain most of it — your hair type and your porosity. Learn them once and every future decision gets easier. This is the foundation our complete hair-care guide is built on.

Key takeaways

  • Hair type = curl pattern (straight, wavy, curly, coily) plus strand thickness (fine, medium, coarse).
  • Porosity = how easily your hair absorbs and holds moisture. It drives how products and heat behave.
  • Both can be tested at home in a few minutes.
More on HairHair Care, Decoded: The Complete Guide for Every Hair Type

Find your curl pattern and thickness

Curl pattern is usually described in four families: Type 1 straight, Type 2 wavy, Type 3 curly, and Type 4 coily. For thickness, hold a single strand: if you can barely feel it, it's fine; if it feels like a thick thread, it's coarse. Thickness decides how much heat and weight your hair can take — fine hair needs gentler tools (see the best dryers for fine hair), while coarse hair often needs more (see flat irons for thick, curly hair).

The porosity float test

Drop a clean, dry strand into a glass of water and wait two to three minutes. If it sinks quickly, you likely have high porosity (absorbs fast, loses moisture fast). If it floats, low porosity (resists moisture; products sit on top). If it hovers in the middle, you're in the balanced sweet spot.

What your results mean

High porosity hair loves rich masks and sealing oils to hold moisture in — our hair mask guide is a good next stop. Low porosity hair does better with lightweight products and a little warmth to help them absorb, and it's pickier about shampoo, so the shampoo guide is worth a read. Whatever your result, protect it: porosity also affects how heat behaves, so a heat protectant is always worth using.

More on HairThe Best Hair Dryers for Fine, Thin Hair

Now build the routine

Once you know your type and porosity, the last piece is sequence. Head to the right order to apply your hair products to put it all together.