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Hair thickness. It’s an area of concern for all of us at some stage or another. Whether it’s alopecia or chemotherapy, hair thinning and loss have medical links to cause significant emotional distress. But is there a scientific way to measure the thickness of your hair? And can you change it?

Here’s everything you need to know about hair density and thickness.

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Studio Firma/Stocksy United

In the simplest possible terms:

  • Thick hair is when there’s a lot of hair per square inch of scalp (either due to width or follicle count).
  • Thin hair is the opposite.

First things first, thick hair doesn’t necessarily mean healthy hair. Some peeps desire thick hair because they associate it with fuller, healthier-looking hair. Many folks try to avoid thinner hair because of its perceived links to unhealthy hair and hair loss.

However, those are only the broadest and most common meanings in the thick vs. thin hair debate. Having thin hair doesn’t mean it’s unhealthy unless your hair was thick beforehand.

Is my hair thick?

If the following problems resonate with you, you’re probably rocking a crop that’s on the thicker side:

  • You have to unclog your shower drain all the time.
  • They don’t make brush handles strong enough to get the damn things through your hair.
  • You run out of shampoo and conditioner fast.
  • Your hair stays damp all day if you don’t dry it properly.
  • You don’t travel anywhere without your lint roller.
  • You can knit a sweater from the amount of hair left on your brushes.
  • Despite the hair lost to brushes and drains, you never seem to run out of hair.
  • Your hair freezes in winter if you half-ass dry it.
  • Pixie cuts make you look like you have a secret electrical socket licking habit.
  • Sweatbands for your neck” doesn’t seem like a totally stupid invention.
  • Humidity gives you all the frizz.
  • Your name is Hermione Granger.

If this all sounds familiar, then you have thick hair. (Except you, Hermione. You can put your hand down now, we know you’re clever.)

Is my hair thin?

If that list didn’t hit different, it doesn’t mean you have thin hair. You may just have average hair which isn’t notably thick or thin.

But If any of these hit home, you’re on Team Thin Hair:

  • The hype around dry shampoo is a mystery.
  • Hats are more than just an aesthetic accessory. (Sunburned scalp, anyone?)
  • When your friends are moaning about frizz and humidity, you’re sneaking looks in the mirror because your hair’s looking particularly full and voluminous.
  • The family comb has been with you for 6 generations.
  • Static electricity and dry weather have the exact same effect.
  • “Braids? Ponytails? Buns? No thanks, I’ll pass.”
  • Keeping back the grease is a full-time job.
  • “Please stop suggesting volumizing products to me.”
  • “Yes, I know about layered cuts.”
  • Shampoo and conditioner are a quarterly purchase.
  • Hairspray is an always-on-hand product.
  • Wind is your natural enemy.
  • Styling your hair is 45 minutes of effort for 30 seconds of the look you want.
  • They don’t make hair ties small enough.

There are upsides and downsides to both thin and thick hair. And, despite how it may seem sometimes, it really isn’t a case of “thick hair good, thin hair bad.”

There are a lot of different hair types. Thick vs. thin is a massive oversimplification. Many people have relatively sparse hair made up of strong, moisture-retaining individual strands. Loads of other folk have an incredibly overpopulated scalp sprouting a sea of wispy spider-silk.

Working out thickness and density

It’s easy to find out your hair type, and you can do it at home. All you need is a mirror and a brush.

Take your brush and part some hair to the side. If you have thick hair, you’ll see no scalp, maybe even at the roots. If you have thin hair, there’ll be mucho scalpage at the point of the parting, and it’ll possibly be visible through the hair itself.

If you want to measure the thickness of individual strands, pluck one out (youch!) and run it between your fingertips. If it feels like frayed silk you have fine, narrow strands of hair. If it feels more like a fishing line, you have thick strands.

Peeps who are still unsure can compare their head hair to other body hair. Arm and leg hairs are finer than head hair. Conversely, underarm hair and pubes are thicker. Take a strand of each. Whichever your scalp strands more closely resemble will give you the answer.

What about porosity?

Porosity is a measure of your hairs’ ability to retain moisture, and can also factor into thickness. To skim the edges of the science, it’s to do with how close the outermost layer of the strands are to the core (yaaaaay, microscope stuff).

You can test your hair porosity with a glass of water. Wash and dry your hair thoroughly, then drop a strand in the glass. If it floats at the top a while before it sinks it’s a sign of low hair porosity (not much space between the outer hair cuticle and the inner ones, so there’s no empty space to take in and store moisture).

Porosity only has a minor influence on hair thickness. However, understanding how your own hair takes (or doesn’t take) moisture is key to a healthy hair care routine whether it’s for thick or thin hair.

Yes, although it’s not as simple as deciding you want thicker hair and then taking a thicker hair pill (they don’t work, don’t believe your spam folder). The only exception is Minoxidil, which research shows may help prevent hair thinning to some degree.

However, don’t trust anyone in your inbox even if that’s what they’re peddling. Spam email quacks have nothing for you. Speak with your actual doctor.

The easiest way to influence your hair type is to find shampoos or conditioners designed to turn your current hair type into your desired one. Whether you want to increase or reduce thickness, there will be a brand and shampoo for you.

Keratin-based shampoos or those labeled as anti-frizz work wonders for thickness reduction. For gains, anything biotin-based or rich in oil can do the trick.

But again, none of these (except for Minoxidil) actually change hair diameter, they just coat it to make it appear thicker.

How to get thicker hair

The key to getting thicker hair is getting the nutrients and vitamins healthy hair needs. B-complex vitamins in particular are important for hair growth, but having a nutritious, balanced diet overall still puts you in a better position.

There are plenty of natural remedies for hair growth and density available that some studies support in part. However, the research is pretty inconclusive. And no hair growth or thickening treatment is guaranteed to be effective and they’re unlikely to affect strand diameter.

Oh, and if you’re really worried about your hair not being thick enough, it’s best to avoid:

  • sprays
  • dyes
  • hot styling tools
  • sulfate products
  • excessive towel/blow-drying

All of these can make your hair thinner.

How to get thinner hair

There are a couple of options for thinner hair. The easiest is a haircut. There are even scissors that are called thinning scissors. Problem solved, see you again in a few weeks.

If you’re growing your hair out or regular haircuts just aren’t your bag, other options are available. Permanent and nonpermanent straightening treatments are available at most hair salons.

Those who want thin hair without straightening it might find some joy in blow-dry creams, as they can help protect hair against heat.

The density of hair follicles and the thickness of individual strands determine hair thickness. You can tell whether you have thick or thin hair at home with a brush and mirror.

There aren’t guaranteed ways to do this, but it’s possible to make your hair thicker or thinner to some degree. There are plenty of readily available hair care products designed for both, and there are also natural remedies like upping your B-vitamin intake (if you’re low in B and that’s what’s leading to more shedding).

The majority of folk looking to get thicker or thinner hair do so for cosmetic reasons. However, there are many medical conditions that could also have you seeking out a way to control your hair density, especially in the context of slowing or reversing hair loss due to conditions like alopecia or side effects of treatments like chemotherapy.

The big takeaway is that our hair is important, and we should look after it, however thick it is.