What Does Your Hair Type Actually Tell You?

Researched and written by Curl Centric. Read by an AI voice.

The 1A to 4C chart started with a stylist's book, not a lab. We explain how to read it, what it can't tell you about your hair, and what to check instead when you choose products.

Podcast: Play in new window | Download

The full guide, with every source: Hair Typing System: The Curl Pattern Chart, 1A to 4C.

Our hair porosity quiz: https://www.curlcentric.com/hair-porosity-test/

Transcript

This is Curl Science by Curl Centric.

If you've ever stood in the hair aisle trying to remember whether you're a 3C or a 4A, you're not alone. The hair type chart is one of the first things most of us learn about our curls. In this episode, we'll tell you how to read it, where it came from, and what it can and can't tell you about your hair. Then we'll explain what to check instead when you're choosing products.

Let's start with the chart itself. It sorts hair into four types by shape. Type 1 is straight, type 2 is wavy, type 3 is curly, and type 4 is coily.

Each type then gets a letter: A, B, or C. For waves, curls, and coils, the letter describes the size of the pattern. A is the loosest and widest, and C is the tightest.

It helps to picture them with things you already own. A 3A curl is about as wide as a stick of sidewalk chalk. A 3B curl is closer to a permanent marker. A 3C curl is about the width of a pencil. And 4A coils are about as wide as a crochet needle. Those comparisons are our own guide, not a lab measurement, but they're a handy way to hold up a strand and compare.

Type 4 also changes shape as it tightens. A 4A coil has an S you can see when you stretch it. A 4B strand bends at sharper angles, more like a Z than an S. And 4C is usually described as having the least visible definition and the most shrinkage on the chart.

So where did this chart come from? Andre Walker, Oprah Winfrey's longtime stylist, says he developed it in 1997 for his book, Andre Talks Hair. He built it to go with his line of hair products, and each type on his chart points to one of them.

Here's the part that surprises people. His chart had ten boxes, not twelve. Type 3 stopped at 3B, and type 4 stopped at 4B. There was no 3C or 4C. The natural hair community added both later to describe hair the original chart left out.

Walker didn't even name it the Andre Walker Hair Typing System. He's said that he found out years later that bloggers were calling it that. And he's said he never meant the numbers as a ranking. A 4C isn't a lower grade than a 2A. The numbers only describe shape.

To find your type, wash your hair and let it air-dry without styling products, since products can change how a strand behaves. Then pull one strand away from your scalp and look at its pattern.

Check a few more spots, including your nape, crown, and edges. In one lab study, strands taken from one person's head landed in four different curl groups. So if you have more than one pattern, that's completely normal. Most people go by the pattern they see most.

The shape of your curl starts under your skin, in the follicle, which is the tiny pocket in your scalp that each strand grows from. Researchers found that curly hair grows from a curved follicle, with the bulb at the bottom bent like a golf club. When they grew those follicles in a dish, they still produced curved hair.

That curve appears across every background. In one study of 230 Japanese women, almost half had curved hair. And when researchers sorted hair by curl alone, people from every self-described race group landed in three or four different curl groups. Curl comes from the shape of your follicles, whatever your background.

Scientists have tried to build a more exact chart. Researchers at L'Oreal measured hair from 1,442 people in 18 countries. They measured how wide each curl was, how far it stretched, and how many waves fit into a set length. That gave them eight curl types, sorted without referring to ethnicity. They later expanded the sample to 2,449 people.

But even that system has limits. When three trained researchers used it to sort the same strands, they agreed only fair to moderately often. The authors called the system unreliable. So if you can't decide between two curl types, that's normal. Trained researchers can't always agree either.

Before we get to what the chart can actually tell you, one quick ask. If you want more answers like this, follow the show, so the next one finds you.

The chart's most useful job is showing you how gently to handle your hair. Tighter curls tangle and knot more easily. In one study, 10 to 16 percent of tightly coiled hair shafts from African volunteers had knots, compared with 0.15 percent of hair shafts from European and Asian volunteers. That's why the tightest section of your hair should decide how slowly you detangle.

Dermatologists are also starting to study curl pattern. In a 2022 study of 74 women with hair loss, tighter curl patterns were associated with higher odds of a scarring type of hair loss called CCCA. The authors found that curl pattern appeared to matter more than ethnicity. And the first source that paper cites is our hair type guide.

Now, here's what the chart can't tell you. It doesn't tell you your density, which is how many hairs grow on your head. In one study, density ranged from 90 to 290 hairs per square centimeter within one group of people. So two women with the same curl type can have about three times as many hairs as each other.

It doesn't tell you how thick each strand is, either. Strand thickness overlaps across curl types, and strands from the same head can differ considerably. In one study, three strands from one person's head measured 81, 119, and 127 micrometers across. The thickest was about half again as wide as the thinnest. One strand describes that strand, not your whole head.

And it doesn't tell you your porosity, which is how easily water gets into and out of your hair. Porosity is influenced much more by damage from bleach, permanent color, relaxers, and heat than by your curl type. A wavy strand and a coily strand can have the same porosity.

Those three things often matter more than curl type when you're choosing products. Fine strands on a low-density head may feel weighed down by a heavy butter that thick, dense hair handles easily. Damaged hair often needs more conditioning than undamaged hair with the same curl pattern.

The chart also has its biggest blind spot right where many of us live. Researchers found that people describe their own curl type inconsistently and that the tightest category hides much of the variety in tightly coiled hair. The label 4C covers a huge range of hair with only one letter.

Can your curl pattern change? Yes, in a few ways. Heat is the big one. In one lab study, curly hair that was repeatedly flat-ironed at 120 to 175 degrees Celsius, or about 250 to 350 degrees Fahrenheit, straightened permanently. The damage stays in the hair you already have, but your follicles don't change. New growth still comes in with your natural pattern.

Relaxers and perms also change the hair that was treated, not the follicle underneath it.

Some medications can change your curl pattern, too. A review of 31 studies found that certain cancer drugs, seizure medications, and acne medications called retinoids can make hair curlier. The change often went away after treatment. Curl can also become more irregular as you age, and many women notice changes during pregnancy. If your curls change, work with the pattern you have now.

So here's what we'd do. Use the chart as a starting point. It's helpful for describing your hair to a stylist, finding videos from people with hair like yours, and deciding how gently to detangle. Then check your density, strand thickness, and porosity separately because those traits help determine which products work. If your hair has more than one pattern, care for the tightest section first.

We drew all twelve types on one free page that you can print and hold next to a strand, with no email required. The link is in the show notes, along with our porosity quiz. And if this helped you understand your hair, follow the show for the next one.

That's it for this episode. If it helped, follow Curl Science in your podcast app so the next one reaches you, and leave us a rating while you're there. Curl Science is researched and written by the Curl Centric team, and it's read by an AI voice.