The hair typing system is a classification method that sorts all human hair into four main types based on curl pattern: Type 1 (straight), Type 2 (wavy), Type 3 (curly), and Type 4 (coily/kinky). Each type breaks down further into subcategories A, B, and C, creating a spectrum from perfectly straight (1A) to tightly coiled (4C). The system was created by celebrity hairstylist Andre Walker and has become the most widely used framework for talking about hair texture, though it has real limitations that are worth understanding.
How the Four Types Are Defined
The system organizes hair by its visible curl pattern, which is determined by the shape of the hair follicle underneath the skin. Straight hair grows from a round follicle that sits perpendicular to the scalp. As hair gets curlier, the follicle becomes more oval in cross-section and tilts at a steeper angle. By Type 4, the follicle is significantly curved in two directions, a feature called retro-curvature, which sets the coil shape before the hair even exits the skin.
Type 1 hair hangs flat with no bend or wave. Because the strand is smooth and the cuticle lies flat, natural oils travel easily from scalp to tips, making this type the most prone to looking greasy. Type 2 hair has a visible S-shaped wave that ranges from loose and fine (2A) to thick waves often mistaken for curls (2C). Type 3 hair forms three-dimensional spirals that look like waves when wet but spring into defined curls as they dry. Type 4 hair coils tightly, sometimes in a visible spring pattern (4A) and sometimes in a zigzag so tight it can appear to have no defined curl at all (4C).
What the A, B, and C Subcategories Mean
Within each numbered type, the letter subcategories reflect differences in strand diameter and coarseness. Moving from A to C, the individual strands get thicker, the texture gets coarser, and the pattern generally becomes tighter or more pronounced. In practical terms:
- 1A: Fine, completely flat, and resistant to holding a curl.
- 1B: Straight with slightly more body.
- 1C: Still straight but noticeably thicker, with some frizz in humid conditions.
- 2A: Fine with subtle, barely-there waves.
- 2B: More defined waves with added frizz.
- 2C: Thick, coarse waves that border on curly.
- 3A: Large, loose spiral curls, typically fine to medium in texture.
- 3B and 3C: Progressively tighter ringlets with more volume.
- 4A: Dense, springy coils with visible definition.
- 4B and 4C: Very tight coils or Z-shaped patterns with significant shrinkage.
Type 3 is the category most likely to feature mixed textures on the same head. Individual strands can range from thin to thick, and the curl diameter can vary from one section of hair to another.
Why Curl Pattern Alone Doesn’t Tell the Whole Story
The biggest criticism of the hair typing system is that it focuses almost entirely on what hair looks like, not how it behaves. Two people with the same curl pattern can have completely different moisture needs, product tolerances, and breakage tendencies. The properties that actually dictate how your hair responds to care, particularly porosity, density, and elasticity, aren’t captured by a number and letter.
Porosity describes how easily your hair absorbs and holds onto water. Low-porosity hair resists moisture: water beads up on the strand’s surface instead of soaking in, and heavy products tend to sit on top and weigh the hair down. High-porosity hair absorbs water quickly but loses it just as fast, often needing richer products and more frequent moisture treatments. Porosity can also change over time. Bleaching or heat damage, for example, raises porosity by lifting the cuticle layer, which is why chemically processed hair sometimes feels softer when wet (it’s absorbing more water) but dries out faster.
Knowing your porosity matters more for product selection than knowing whether you’re a 3B or a 3C. Someone with low-porosity 4A hair and someone with high-porosity 4A hair need fundamentally different routines, even though they share a curl pattern.
How to Identify Your Type and Properties
Start with curl pattern, since it’s the easiest to see. Wash your hair, skip all styling products, and let it air dry. The shape it takes on its own is your baseline type. If it lies flat, you’re Type 1. If it forms an S-wave, Type 2. Spirals and ringlets indicate Type 3, and tight coils or zigzags point to Type 4.
For density, part your hair at the front and pull it to the side while facing a mirror. If you can clearly see your scalp, your density is low. If you can barely see it, density is high. For strand thickness, pinch a single hair between your thumb and index finger. If you can barely feel it, you have fine strands. If it feels like a piece of thread, your strands are coarse.
To test porosity at home, drop a clean strand of hair into a bowl of water. Hair that floats is low porosity. Hair that sinks slowly has medium porosity. Hair that drops to the bottom quickly is high porosity. For elasticity, gently stretch a wet strand. Healthy hair with good elasticity will stretch noticeably before springing back. Hair that snaps with little stretch is low in elasticity and likely needs protein-based treatments.
Alternative Systems
The LOIS system was developed as an alternative that moves away from numbers entirely. Instead of assigning a type, it describes the actual shape each strand makes: L (a sharp bend), O (a round coil), I (straight with no curve), and S (a wave). It also accounts for strand size and sheen, which the Walker system doesn’t address. The tradeoff is that LOIS doesn’t capture curl diameter or tightness, so it can be harder to use when comparing your hair to someone else’s for product recommendations.
L’Oréal has its own classification system used in research settings, but it largely mirrors the Walker system’s structure of four main types with subcategories. In everyday conversations about hair care, the Walker system remains the default.
What the System Gets Right and Wrong
The hair typing system works well as a shared vocabulary. It gives people a quick way to communicate what their hair looks like, find tutorials from people with similar textures, and narrow down product recommendations. Before the system existed, describing your hair to a stylist or searching for advice online was far less precise.
Where it falls short is in implying that curl pattern is the most important thing about your hair. The biological structure of curly and coily hair makes it inherently more fragile than straight hair. The twisting follicle creates spots where the outer cuticle lifts, leaving the strand vulnerable to damage. There’s also less of the structural protein in the center of each strand, which makes breakage more likely. These structural realities affect Types 3 and 4 across all subcategories, but the degree of dryness, damage risk, and product need within those types varies enormously based on porosity and thickness.
The most useful approach is to treat your hair type number as a starting point for finding people with similar-looking hair, then refine your routine based on porosity, density, and elasticity. Those properties, not the curl pattern itself, determine which products your hair will actually absorb and benefit from.