How to Measure Thickness of Hair

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You wouldn’t think it, but the average person has just over 100,000 hairs on their scalp, but it’s just one of the factors which determine how thick your hair will be. So what are the main factors which determine hair thickness and how can you measure it?

If you’re anything like me, a little hair-obsessed? Then you’re probably always looking for ways to improve hair growth and measure your progress.

In this article, I’ll go over several things

  1. What determines hair thickness
  2. Classifying hair types
  3. Ways to measure hair thickness
  4. What makes your hair appear thinner than it really is

Main factors which determine your hair thickness

Hair color

There appears to be a correlation between hair color and how many hair follicles on the scalp. Obviously, it’s not the hair color itself, but probably a genetic and evolutionary adaptation.

It’s been found that people who are naturally blonde (like myself) have between 120,000 to 150,000 hairs on the scalp.

Brunettes have between 100,000 to 120,000 hairs on their scalp.

And people with red hair have even fewer hairs, usually between 80,000 to 90,000 hairs on their scalp.

Hair strand type

Fine hair – Hair strands tend to be very thin and even have a translucent quality to them if held up to the light.

Normal hair – Each individual strand of hair doesn’t feel fine or particularly coarse when you run your hands through your hair. You’ll find this type of hair most often on Caucasian persons.

Coarse hair – Texture will feel a bit rougher and hair can easily be seen against different types of surfaces.

Depending on how thick each individual strand of hair is can have a massive impact on the overall thickness of your hair.

Other factors such as whether the hair is straight, wavy, curly will impact how thick it appears.

Your age

That’s right – the older you are, the harder it’s going to be to maintain the hair thickness you once had in your late teens. Of course, by paying attention to your diet, eating well, exercising and generally taking care of your hair, you may be able to maintain a higher number of active hair follicles on your scalp for longer.


Genes play an important role in how long each strand of hair can continue to grow. Some people can grow their hair for up to 10 years before it falls out.  The average person though will have a growth cycle which lasts anywhere between 3 – 7 years.

I may have been lucky in this regard. My hair just seems to grow and grow. My sister has also grown hair much longer than mine, and hers grew for more than 10 years until she finally cut it.


Getting adequate levels of vitamins and minerals to support healthy hair growth is super important. There are many nutrients that are involved in hair growth, and any deficiencies will lead to increased hair loss and a decrease in overall hair thickness.

How do you actually measure hair thickness?

So now that we know the ins and outs of how and why hair thickness can vary from person to person, let’s look at how you can measure your progress in increasing hair thickness.

Measuring ponytail circumference

If you have hair which you can put in a ponytail, you can quite easily measure the variations in hair thickness over time.

It’s important to look at trends. Hair growth cycles, so what you want to look for is a positive trend upwards, even if there are some decreases in hair thickness at certain points. For example, hair fall in the autumn can temporarily decrease hair ponytail circumference.

Thin hair – Measures less than 2 inches

Normal hair – Measures between 2 – 4 inches

Thick hair – Measures over 4 inches

My own hair is usually somewhere between 3.75 and just over 4 inches depending on whether it’s just washed or not. My absolute lowest ponytail circumference was about 3.25 inches when I had a zinc deficiency, but I reversed hair loss after taking zinc supplements. Even now, I still continue to see improvements in hair thickness!

How to measure

  1. Get some cotton yarn to use for measuring the circumference of the ponytail
  2. Grab one of your hair bands and get as much hair as you can into it and tighten it so it’s secure
  3. Make a slipknot with the cotton yawn
  4. Between the scalp and your hairband, place the loop as close to the scalp as possible
  5. Tighten the slipknot until it can’t be tightened anymore and then slowly pull it off your ponytail to measure
  6. Cut the slipknot and then measure the length of the cotton yarn using a ruler or tape measure

What makes hair look thinner?

Hair can sometimes appear much thinner than it really is because of a few reasons!

Also, remember that in order to get a good measurement of hair thickness, make sure that you have clean and freshly washed hair that has had plenty of time to dry!

So, back to your hair looking thinner sometimes… it can be caused by the following:

  • Oily hair and scalp causing hair to clump together and become stringy
  • Heavy products in your hair and heavy conditioners can make hair look thinner
  • Are you using hair straighteners? 🙂
  • You’ve not clarified your hair in a long time
  • The type of hairbrush you’re using
  • You don’t have many layers to your hair. Much of it is one length.
  • You haven’t learned the trick to blow dry your hair with your head upside down. 😉

To finish…

Measuring hair thickness can be a great way to see the progress you’re making whether it be preventing hair loss or trying to increase hair growth and trying to grow thicker hair.

Hair grows pretty slowly, so don’t be too worried if you don’t see much change within a month or two. I’d recommend that you measure your hair every 3-4 months at least, because that way, you’ll give much of your new hairs more chance to reach ponytail length to see a significant difference.

Of course, it wouldn’t hurt measuring hair thickness more often if you want to keep a closer eye on your progress!


  • Reply
    January 27, 2020 at 7:52 pm

    Should I do this hair on freshly washed hair ? Or stretched hair?

    • Reply
      January 28, 2020 at 9:38 am

      Wash your hair first and measure after drying. If there is a lot of product in there, it might be worth using a clarifying shampoo as well. Just be consistent with how you measure the thickness. 🙂

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