The hair-typing chart was invented for styling advice, not shopping. It groups every head on earth into a handful of letters and numbers, and then the hair industry borrowed it as a sizing system. That is how women end up with "4C" wefts that look nothing like their own 4C.
What a label hides
Two things decide whether hair reads as one texture: how tight the coil is, and what shape it makes. A label like 4C compresses both into one box. The coil itself is set deep in the follicle: curly fibres grow from curved follicles, and the cortex inside packs unevenly, with one cell population gathering on the concave side of the bend and another on the convex side.1 That built-in asymmetry is what makes a coil a coil, and why two coils can differ in ways a single letter never captures.
Coil tightness is measurable. Researchers describe curl with geometric measures like curvature degree, width and amplitude rather than a single letter, which is exactly the kind of detail a letter throws away.1 You can borrow the idea at home: wrap a strand around a pen and you can see the diameter of the curl it makes; some coils wind at three millimetres, some at nine, and both might get called 4C. Shape is the second axis: some hair bends in soft S curves, some in sharp Z angles. An S coil and a Z coil of similar tightness sit differently, reflect light differently, and blend differently.
This is why every Adéorí product page carries a spec block: coil size in millimetres, pattern S or Z. Not because the numbers are impressive, but because they are checkable. You can look at your own hair and compare.
Why the typing chart falls apart at the register
The Andre Walker system was built to sort styling routines, not to size a weft. A stylist devised it in the 1990s, and it was originally created to help market a line of hair products, not as peer-reviewed science. It answers a broad question, is your hair straight, wavy, curly, or coily, and it answers it well enough for a shelf of conditioner. It was never meant to promise that two heads labelled 4C will blend into the same hair. It also assumes one number can speak for a whole head, when hair commonly shifts pattern from crown to nape. They often will not.
The gap inside 4C is as wide as the gap between 4A and 4C, and nobody prints a letter for it. One woman's 4C springs like a phone cord. Another woman's bends in tight zigzags with barely any spring. Same label, different hair, and a weft matched to the label instead of the coil sits wrong on at least one of them. Coil size can tell those two heads apart. A letter cannot.
S coils and Z coils are not the same hair
People treat S and Z as a footnote. It is not. The shape changes how the hair behaves before tightness ever enters the conversation.
An S coil turns in rounded arcs, like a ribbon curled over scissors. Light rolls along those curves, so an S pattern reads glossier and clumps into defined coils on its own. A Z coil turns in hard angles, folding back on itself at sharp corners. It catches light in more directions, so it reads more matte and fuller, and holds a shape without much help. Neither is better. They are different tools.
Here is where it matters. Put a defined S weft against a Z leave-out and the seam shows, because one side stacks neat spirals and the other zigzags into density. The tightness can match to the millimetre and the eye still finds the line. Match the shape first, then the size. Folds in angles, you want a Z. Curls in rounds, you want an S.
| S coil | Z coil | |
|---|---|---|
| Bend shape | Rounded, spiralling turns | Sharp, angular zigzag turns |
| Looks like | Springs and ringlets | Tight folds, cotton-dense |
| How it catches light | More visible sheen | Matte, reads fuller |
| Blends cleanly with | Other S coils of similar tightness | Other Z coils of similar tightness |
How to read your own hair
- Work with clean, dry, product-free hair in its natural state. Stretched or braided-out hair lies to you.
- Look at the section that will sit against the extension, usually your leave-out or hairline. Most heads carry more than one pattern; the nape is often tighter than the crown.
- Check the coil against a familiar object. Pen-spring tight? Pencil width? Wider?
- Then check the angle. Rounded turns are S. Sharp zigzag turns are Z.
Five minutes of looking beats an hour of comparing labels.
Measuring the coil so the number means something
Reading is enough for most people. If you want the actual number, it takes one strand and something round. Let a single coil relax, then wind it once around a common object. A pen barrel runs close to nine millimetres across. A pencil sits nearer seven. A thin straw or coffee stirrer lands around three to four. Whichever object the coil hugs naturally is roughly your diameter, and that is the number to hold against a product spec.
Two cautions. Take the reading dry and untouched; water and product both loosen the coil and hand you a looser number than you actually wear. And read the section that meets the weft, not your loosest patch. If your crown coils wide but your hairline coils tight, the hairline is what has to match.
When you sit between two textures
Take the tighter one. A tighter coil blends into a looser head far more forgivingly than a looser coil disappears into a tighter one. And if you are genuinely torn, email support@adeori.com with a photo of your hair as you wear it. A person answers, and we would rather match you slowly than sell you the wrong weft fast.
Common questions
Is my hair type wrong if two 4C wefts look different?
No. Your hair type is not the problem; the label is doing too much work. 4C covers a wide band of coil sizes and both S and Z shapes. Two wefts can honestly be sold as 4C and still not match each other, or you. Ignore the letter and compare the coil size and pattern instead.
What if my hair is between an S and a Z?
Plenty of hair is. Look at how the coil turns when it is fully dry: rounded bends read as S, sharp corners read as Z. When it is a true toss-up, a Z weft carries more density and hides a soft leave-out better, so it tends to be the safer pick.
Does coil size change with length?
The diameter of an individual coil stays about the same. What changes with length is how much shrinkage you see and how much the weight of longer hair stretches the pattern out. Match by the coil size at the root section, not by how long you plan to wear it.
The Texture Match Guide lays every texture out from loosest to tightest, and the quiz does the reading for you in about a minute.
1 Cloete, E., Khumalo, N.P., Ngoepe, M.N. (2019). The what, why and how of curly hair: a review. Proceedings of the Royal Society A, 475(2231). ncbi.nlm.nih.gov.