1A Hair Type: What It Is and How It Differs From 1B and 1C

1A hair type is the straightest hair on the typing chart. It has no wave and no bend, and the strands are usually fine. Most people who look it up are trying to place their own hair between 1A, 1B and 1C.

This guide covers what 1A hair type means, how it differs from 1B and 1C, how to test your own hair, why "1B" also turns up as a color code, and how to match extensions to straight hair.

The hair typing chart most guides use sorts hair by shape. The number runs from 1 to 4: straight, wavy, curly, coily. The letter runs from A to C inside each number. Hairstylist Andre Walker made the system popular in the 1990s.

So 1A hair type sits at the first position on the chart. Allure and Byrdie describe it the same way: completely straight, fine, flat at the root, shiny, quick to turn oily and hard to curl (both checked 8 October 2026).

The shine and the oil have one cause. Scalp oil travels down a straight strand with nothing in its way.

No lab or industry body defines these types. They are descriptions that stylists and brands share, which is why two guides can place the same head of hair one letter apart.

The descriptions for 1B and 1C follow salon guides from Hairicc and Sunday Salon and the type 1 guide from Function of Beauty (checked 8 October 2026). Your hair can sit between two columns. Many heads show two types at once.

You need clean hair, no product and about an hour.

1. Wash and condition as usual. Use no leave-in, no mousse and no oil.
2. Let the hair air dry. Don't brush it, twist it or tie it while it dries.
3. Look at the last 3 inches. If they hang straight down with no bend at all, that points to 1A. If they curve in or flip out, that points to 1B.
4. Look at the whole length in a mirror. Two or three loose bends and some frizz around the crown point to 1C.
5. Curl one section with an iron and no product. Hair that drops the curl within the hour is behaving like 1A.

Hair type is one of three things people mix together. Type is the shape. Strand thickness is how wide a single hair is: fine, medium or coarse. Density is how many hairs you have. A person can have 1A hair that is fine and dense, and it still looks flat because each strand is so thin.

Search for 1A hair type and you'll soon meet "1B" used in a second way. The two have nothing to do with each other.

• 1B hair type. A shape. Straight hair with some body and ends that bend.
• #1B hair color. A shade code on hair extensions. It means natural black, an off-black with a faint brown cast.

A client with 1A hair type can be #1B in color. A client with 1B hair type can be blonde. When you order extensions, the type tells you which texture to pick and the color code tells you which shade. Write both on the order.

Extensions show when their texture differs from the hair around them. On 1A hair type there is no wave to hide a join, so a body wave weft sits on top of pin-straight hair and reads as two separate textures.

Bone straight is the straight texture in our range. It is the match for 1A and for most 1B hair. Our guide to bone straight hair covers how that texture is made and how it behaves.

1C is the tricky one. The client's own hair has bends and some frizz, and a flat extension beside it looks too sleek. Two fixes work. Blow-dry the client's hair smooth so it meets the extension, or put a soft bend into the extension with a heat tool. Human hair extensions take heat styling the same way natural hair does.

Check shine too. 1A hair is naturally glossy. Hold the sample against the client's hair by a window and make sure the two reflect light alike.

1A hair type is usually fine, and fine hair carries less weight. Every tape, bond or bead hangs from a small section of the client's own hair. A thin section under a heavy piece breaks at the attachment.

So the planning runs the other way from thick hair. Use lighter pieces, more of them, and a shorter length. Our guide to the best hair extensions for thin hair ranks the methods by how much load they put on the root.

Slip is the second problem. Fine straight hair is smooth, and stylists often find that clips and beads slide down it faster than they do on thicker hair. Ask the stylist how they stop that before you choose a method.

Flat hair also hides less. With no volume at the root, an attachment placed too high shows through. Keep rows lower and further from the parting than you would on 1C hair.

1A hair type gets oily at the root quickly, and oil loosens tape and keratin bonds. The two facts pull against each other, so the routine matters.

• Wash at the scalp. Shampoo at the root as often as the oil needs. Let the lather rinse through the extensions.
• Keep conditioner low. Mid-lengths and ends only. Conditioner on the attachments softens them and weighs the root down.
• Skip heavy products. Oils, creams and serums flatten 1A hair and travel to the bonds. A light volumising spray at the root does more.
• Dry the attachments. Don't sleep on damp roots. Wet bonds twist and slip.

How long each method stays in, and what shortens it, is in how long hair extensions last.

The 1A hair type chart describes hair growing on a head. At the factory we sort by length, drawn type, texture and color, and we send a sample so the stylist can judge the match by hand.

The testing minimum is one bundle or one pack at 100 grams, sold at the normal price. For a texture match that is the right order: hold it against the client's hair before you buy for a full head.

Frequently asked questions