How to Identify Your Hair Type The 7 Type System Used by Trichologists

Knowing your hair type is the single most useful thing you can do for your hair. Most people use the wrong products because they describe their hair by texture alone ("wavy" or "thick"). Trichologists actually use a 4-axis system: curl pattern, porosity, density, and strand thickness. This guide walks through each axis with a quick self-test you can do at home. If you have ever wondered why one shampoo works for your friend but not for you, the answer is usually in one of these four axes, not in the shampoo itself. Is Argan Oil Good for Hair? Discover the Benefits for Hair and Skin explains why.

Why "Knowing Your Hair Type" Is the First Step to Better Hair

Buying products by hair type is not about marketing segments. Different hair structures physically absorb ingredients differently. Low-porosity hair resists moisture, high-porosity hair loses it fast, and each requires a different delivery vehicle. The hair type chart below maps the most common product recommendations to each axis.

The Trichologist's 4-Axis System

The 4-axis framework was developed to move beyond the "wavy / curly / straight" marketing category. Two people with the same curl pattern can have completely different porosity and density, and therefore need different routines.

Axis	What it measures	Test you can do at home
Curl pattern	Shape of the strand (1-4)	Air-dry without product and look in mirror
Porosity	How well hair absorbs moisture	Float test on a strand in water
Density	How many strands per square cm	Count strands in a 1cm x 1cm parting
Texture	Thickness of a single strand	Compare to sewing thread

Type 1 to Type 4: Curl Pattern Explained

The Andre Walker curl classification is the most widely cited. Each type has three sub-categories (A, B, C) that reflect how defined the curl is.

• Type 1 (Straight): No curl, tends to be oily, resists curling.
• Type 2 (Wavy): S-Shape pattern, frizz-prone at the root, often needs lightweight moisture.
• Type 3 (Curly): Defined spirals, dry by nature, thrives with rich creams and leave-ins.
• Type 4 (Coily): Tight zig-zag or coiled pattern, very fragile, needs heavy sealing products.

Porosity: Low, Medium, High — and the Float Test

Porosity determines whether moisture can get in and stay in. The float test takes 2 minutes: place a clean strand in a glass of room-temperature water and watch what happens over 4 minutes.

• Low porosity: Floats. Cuticle is closed; products sit on top. Use heat or steam to open cuticle before applying masks.
• Medium porosity: Floats then sinks slowly. Cuticle is balanced; most products work well.
• High porosity: Sinks immediately. Cuticle is damaged or naturally open; needs protein and sealing oils.

Karseell Private Label Hair Care Shampoo and Conditioner – Promotes Healthy Scalp and Hair-OEM And ODM Services Available explains the protein vs moisture balance in more depth.

Density: Thin, Medium, Thick — How to Measure

Density is about the number of strands on your head, not the thickness of each strand. Part your hair and look at your scalp visibility:

• Thin density: You can see your scalp easily across the top of your head. Use lightweight products to avoid flattening.
• Medium density: Some scalp visible at the part, not much elsewhere.
• Thick density: You cannot see your scalp through your hair. Use richer products and section carefully when applying.

Texture: Fine, Medium, Coarse

Compare a single strand to a piece of sewing thread. If the strand is much thinner, you have fine hair. If it is roughly the same, medium. If it is much thicker, coarse. Fine hair breaks more easily, coarse hair absorbs more product. Why Now is the Perfect Time to Partner with Karseell for Hair Care Products covers strand-thickness-related care.

How to Build a Routine Based on Your Profile

Once you have a 4-axis profile, the routine writes itself. The rule of thumb:

• Low porosity + fine + thin: Lightweight water-based products, twice-a-week mask only.
• High porosity + coarse + thick: Heavy butters and oils, daily leave-in, monthly protein treatment.
• Medium everything: Most products will work; pick based on scalp condition (oily vs dry).

How to Maintain and Protect Your Keratin Bonded Hair Extensions shows how to layer products by porosity. Which treatment is best for hair? has the full wash-day schedule by density. Will goat milk make your hair grow back? covers seasonal adjustments for each profile.

FAQ: Hair Type Identification

What is the most common hair type?

Globally, Type 3 (curly) is the most common, accounting for roughly 45% of adults. Type 1 (straight) is around 25%, Type 2 (wavy) about 20%, and Type 4 (coily) about 10%.

Can my hair type change with age?

Curl pattern usually does not change, but porosity and density can. Hormonal shifts, childbirth, and chemotherapy can alter porosity and density temporarily or permanently.

Is porosity genetic?

Partly. Genetics set the baseline; chemical processing, heat, and sun exposure shift it over time. Many people start medium and end up high-porosity after years of color treatment.

How often should I do the porosity float test?

Once per season, or after any major chemical treatment. Porosity shifts slowly so monthly testing is overkill.

Do I need different products for the roots vs ends?

Often yes. Roots tend to be oilier and younger, ends tend to be drier and older. Using one formula across both is the most common mistake.

What is the difference between 2A and 2B?

2A has a very loose S-wave, 2B has more defined S-waves with some frizz at the crown. Both are wavy but require different anti-frizz strategies.

Why is my hair dry even though it is low porosity?

Low-porosity hair can still be dry. The cuticle is closed so moisture cannot get in. Use steam, heat, or a clarifying shampoo weekly to open the cuticle before applying masks.

Should curly hair always use sulfate-free shampoo?

Strong recommendation, not requirement. Sulfates strip the natural oils curly hair depends on for definition. A sulfate-free shampoo preserves curl pattern longer.

Article last updated: 2026-10-06 | Author: Karseell Editorial Team | Reviewed by: Guangzhou Chinchy Cosmetic Group Trichology Partner