What Is Hair Density and Why Does It Matter?

Typically, when we’re categorizing our hair and how to treat it, we’re looking at how thick or long it is. We’ll also look at what texture it is and whether or not it’s processed to determine how often we need a trim. But another, lesser-known metric that should be taken into consideration is hair density.

Um, What Exactly Is Hair Density?

Simply put, hair density is the number of individual strands per square inch on your scalp. (Fun fact: The average person has approximately 2,200 strands of hair per square inch on their head. The average person also sheds between 50 and 100 hairs per day.)

While hair thinness or thickness refers to the circumference of each strand, hair density refers to how thin or thick the collective group of hairs is. That said, someone could have very fine hair that is also very dense (meaning they have a lot of fine hairs per square inch), or they could have thick, but low-density hair (meaning they have thick strands but not so many of them per square inch).

How Do I Figure Out What My Hair Density Is?

Though you could bust out a microscope and get to counting if you really want to kill some time, the much easier way to measure your hair density is to just look at your ponytail.

To do this, tie your hair back and measure the circumference of your tail. If it’s less than two inches, you have low-density hair, if it’s two to three inches, you have medium-density hair and if it’s four or more inches thick in circumference, you have high-density hair.

For ladies (and gentlemen) who have a short bob or pixie that can’t be pulled back into a ponytail, take a closer look at your scalp. If you can easily see it without touching or moving your hair around, you likely have low-density hair. If your scalp is somewhat visible from the top of your head, then you have medium-density hair. And if your scalp is barely visible then you have high-density hair.

Since We’re Measuring Things Now, How Do You Measure Your Hair Thickness?

There are two main ways to go about this. (One is decidedly less painful than the other, but it also depends on how long your hair is.) The first option is to pluck a single strand of hair from your head. We’d recommend pulling one from the back of your head as opposed to a spot in the front.

Now compare the strand to a piece of thread. If the strand is thinner than the thread, you have thin hair. If your hair is the same width as the thread, you have medium hair. If your strand is wider than the thread, you have thick hair.

The other way to test for hair thickness (which is easier if you have longer hair) is to grab a single strand between your fingers and feel it. If you can barely feel anything, you have thin hair and if you can feel it, you have thicker hair. This method is (ahem) a hair less precise than the former, but it will give you a general idea.

Great, Now What Do I Do With This Info?

You mean other than having another fascinating tidbit to share the next time you’re in a conversational lull with someone? (We kid.)

In all seriousness, knowing your hair density is helpful in figuring out what products to use, how to style your hair and how to cut it.

hair density low
McKenzie Cordell for PureWow

What Should I Do If I Have Low-density Hair?

For low-density hair, you’ll want to steer clear of heavier creams and butters and instead opt for lightweight styling products that won’t weigh your hair down, like leave-in sprays, dry shampoos or volumizing foams and/or mousses.

As for what to tell your stylist? You want straight or rounded ends (over feathered cuts or layers) to create more weight and add fullness to your style.

hair density medium
McKenzie Cordell for PureWow

What Are Your Tips For Medium-density Hair?

For medium-density hair, you can use a variety of products to enhance your natural texture. For example, try a mousse and dry shampoo to boost volume at the roots—or creams and butters to calm down the lengths of your hair.

hair density high
McKenzie Cordell for PureWow

And How Should I Approach High-density Hair?

For high-density hair, you’ll want a product with heavier hold like a gel, a cream or a styling butter—especially if you have curly or coily and dense hair. This will help hold your strands together and minimize any puffiness (a la Hermione Granger pre- Goblet of Fire glow up).

High-density hair has a tendency to look and feel a bit heavy, so you can ask your stylist to remove some excess weight (or debulk) your hair. Avoid blunt ends, which can create that pyramid effect, and for any cut that’s above your shoulders, make sure your stylist carefully thins out your ends to lighten things up and give your overall style some movement.

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Beauty Director

Jenny Jin is PureWow’s Beauty Director and is currently based in Los Angeles. Since beginning her journalism career at Real Simple magazine, she has become a human encyclopedia of...