Because hair porosity isn't visible to the naked eye and can't necessarily be felt through the tips of your fingers, it can be difficult to understand whether you fall on the low or high end of the spectrum. But luckily, there's a tried-and-true test that can be done in minutes to test the porosity level of your hair.
First, you'll need to wash your hair thoroughly to ensure there's no sweat, product, or buildup caked onto your strands. Then, brush your hair through with a clean brush, and take a strand of hair that comes out in the brush. Drop it into a clear glass of water.
After a few minutes of allowing the hair to rest in the water, take a look. If the strand is floating, you have low porosity hair. If the strand is sinking, you have high porosity hair. And if the strand is somewhere in the middle of the water, you have medium to normal porosity hair.