Is Your Hair Fine, Medium, or Coarse? How to Measure

Is your hair fine, medium, or coarse? It's not always easy to tell. Healthy hair and dry, environmentally-stressed hair may feel and look very different. You may think your hair is coarse (wide) when it really has some fiber twists and bends (kinking) or is "medium." Dry hair is often described as "coarse" feeling because it feels rough.©Science-y Hair Blog 2013

Measuring is the best way to find out what the dimension of anything actually is. Hair is measured in microns. There are 1000 microns in one millimeter. ©Science-y Hair Blog 2013

Hair Diameter Categories:©Science-y Hair Blog 2013

Fine hair: Less than 60 microns (16 or more hairs per millimeter)

Medium hair: 60-80 microns (12 to 16 hairs per millimeter)

Coarse or wide hair: 80 microns or greater (fewer than 12 hairs per millimeter)

To do this test, you need about 20 hairs which you have shed, and a metric ruler. 

How to choose your sample:

We're assuming that hairs you've shed while washing or on your clothes are a "random sample" meaning they are hairs from all over your head and therefore there is a good chance that these represent your hair in general. If you take hairs from only one part of your head, you may get a inaccurate result. 

Method:

1) Dip the hairs in clean water to rinse them and make them pliable. No knots! Cut them to a manageable length if they are quite long.

2) Line up 10 of the hairs in a drop of water or a drop of hair gel (the water will help them stay in place and prevent them from bending or curling). Pack them as closely as possible without overlapping - use a straight pin or toothpick to press them together. Make sure you count how many hairs you are using. You're going to pack them more tightly than you probably think is correct. Just don't let them overlap. If you do not press them very tightly together, you'll get an estimate which is too large. You'll create a very solid little sheath of hair. There should be no gaps or air spaces. If your hairs are very curly, weight them at each end and gently pull them straight. If you have tightly-curled hair with many kinks, apply coconut oil or another oil to the hairs to make them pliable.

3) Place the ruler gently over the swath of hairs and see how many are fitting into a millimeter. Put the ruler down on the hairs, don't hold it above them. If you can add more, add them, make sure you keep track of how many you added.©Science-y Hair Blog 2013

Then refer back to the list. 

• 15-16 hairs or more pack into a millimeter: Your hair is fine.

• 10-12 pack into a millimeter and you are pressing them tightly: Your hair is medium.

• 10 hairs pack together within a millimeter: Your hair is either medium and has kinks that prevent close packing, or it is coarse.

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• Fine hair is silky when healthy. It bends easily, it is dented easily by ponytail holders and hair pins. It is easily flattened by weight of water, oils and conditioners or or other hairs. Think of milkweed down or little-kid hair. 
• Medium hair has a little more structure. It resists bending a little more than fine hair. Medium hairs are easier to see individually and feel between the fingers - but medium hair behaves a lot like fine hair. In reality, it seems medium and coarse hair are often mixed together on the same head. 
• Coarse hair resists bending. It feels strong between the fingers and is quite visible, even against a similar-colored background. Hair that may not look coarse can give away its coarseness by being very buoyant (in the air) when it's well-hydrated.

This picture if of fine-medium hair. I packed 12-13 of these hairs into one millimeter. You can see it wet, but there's a photograph of the hair dry too because it photographed better. 

Hairs laid out in water - the space between the
smaller marks is one millimeter.

Oops. I made a gap when I put the ruler down.
This will give me an inaccurate result. But the
photo is in better focus.

Same hairs, photographed dry. They spread out a bit
when I put the ruler down - that's why
I suggest using water to hold them in place.

These are the same hairs, all spread out. It's hard to tell from
looking at them like this that so many will pack into
one millimeter.

A word about kinks in hair. Anybody can have kinking in their hair strands. This may be subtle widening and narrowing of the hair shaft. It may be a subtle twist in a similar motion to wringing the water out of a wet cloth. Or it may be lots of tiny bends. You may feel these when you run your fingers over a strand of hair as bumps or roughness, but you may or may not be able to see them. 

Is this method completely accurate? Sorta. It's difficult to handle individual hairs, difficult to pack them close together and difficult to get a good reading on a ruler when we're looking that closely - look at how wide those lines are compared to the actual hairs! But it might get you close. If you pack those little hairs in tightly and also take into consideration the way your hair behaves as well - it should give you a good estimate. You can always have hair which is in-between. Measurements are only as good as the technique of the person doing the measuring. If you feel you got the wrong result, try it again, try it with the hairs dry instead of wet, use a hand lens (magnifying glass) to see your work.

The trickiest part of this method is to get the hairs to stay in place.

©Science-y Hair Blog 2013