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models with various hair types

What is Your Hair Type?

Just like with skincare, haircare responds to unique needs and concerns. Most of us know what our skin type is – but are you across the defining features of your hair type? Alongside categories like wavy, straight and curly hair shapes, there are other factors which determine different hair types.
Hair responds to environmental stress in its own way, and benefits from specially designed haircare products. To strengthen, smooth and add shine to your hair, the right supportive haircare routine is needed.
For those googling ‘what type of hair do I have’, we’ve broken down each category and their features in this simple guide. Read on to understand your unique hair type and the best approach for healthy, happy locks.

What are the different hair types?

Broadly speaking, different hair types can be broken into four textural categories: straight, wavy, curly and coily. Within each are three separate subcategories, which define the variations of each hair type. Let’s look through the four types of hair to help pinpoint yours.

model with straight hair type

1a -1c Straight Hair

The flattest hair type, 1a, 1b and 1c tend to have fine to medium strands. Those with 1a hair types have poker straight hair, which can make attaining volume tricky. 1b can feature a slight wave, with visible ‘S’ waves apparent in 1c hair types. 

curly hair

2a - 2c Wavy Hair

Unlike the sparse waves you may find in straight hair types, 2a, 3b and 2c are defined by the bends which move from root to tip. While 2a hair types feature looser style S waves, the 2c category has more distinct waves and some loose curls. 

curly hair

3a - 3c Curly Hair

The curls in those with type 3 hair wrap around themselves instead of forming an S shape. Typically a dry hair category, curly hair routines include hydrating formulas. This hair type can feature a mix of textures. Where 3a types have big, loose spiral curls, 3b curls err on ringlets, and 3c have tighter corkscrew shaped curls. 

coily hair

4a - 4c Coily Hair

Type 4 hair features tightly coiled curls in a variety of shapes. Scalp oil can’t fully lubricate strands of this hair type, which means that while you’ll avoid oiliness, you may be prone to dryness. 4a feature coiled S curls, 4b’s curls are Z-patterned, and those with 4c hair have very tightly kinked Z-patterned curls.

What is my hair type?

So we know the separate definitions of each category, but how do I find out what my hair type is? As mentioned before, the shape of your strands is not the only attribute that determines hair type. Those with oily or dry skin know that a number of signs and features make up their skin type. Below, we’ve listed the different components that help to classify unique types of hair. You can check them out and then find the best routine for yours with our Online Hair Diagnosis.

brown healthy hair

Hair structure

Different hair types have differently sized strands. The thickness of strands is defined by three categories: fine, medium and coarse. Fine strands have a smaller diameter of hair than medium and coarse. Those with coarse strands have a diameter of around 120 microns – over double those with fine. An easy way to determine your hair structure is by comparing a single strand to a sewing thread. If it appears thinner, you likely have fine hair – larger strands will sit in the medium or coarse category.  


Hair structure isn’t to be confused with ‘thin’ or ‘thick’ hair density though. These terms refer to the number of strands on the scalp – so you could have both coarse and thin hair. 

healthy blonde hair

Hair porosity

Alongside density, thickness and strand shapes, different hair types have unique levels of ‘porosity’. Hair porosity refers to a strand’s ability to absorb water. This matters for the haircare formulas your hair type should use. ‘High porosity’ hair absorbs more moisture, and ‘low porosity’ strands have flat cuticles which block moisture from reaching strands.  


You can check your hair porosity by dropping a strand into a glass of water. High porosity hair will sink to the bottom – this indicates that hair is damaged and releases moisture quickly. Treatments that address frizz and breakage can help here. Hair which floats on the surface is low porosity – it’s recommended that product is applied while hair is still damp, to assist with moisture absorption.  

brown healthy hair

Scalp moisture

Oily or flaky scalps can be tricky to get on top of without the right support. If you’ve noticed dandruff and flaking, your scalp is likely dry. Dry scalp treatments can include gentle and nourishing shampoo and conditioners, alongside nourishing serum treatments.  


If the roots of your hair often appear greasy, you probably have an oily scalp. Oily scalp products address greasy roots and help to re-establish a balanced level of moisture in hair. 

How to care for your hair type

You’re hopefully more confident around types of hair and where yours sits now. To care for different hair types, Kérastase has formulated specific haircare solutions. One of those is the in-salon Fusio-Dose Treatment. A bespoke experience, each Fusio-Dose booster treatment is personalised to you according to your hairdresser’s hair type diagnosis. To access this special experience and address your unique hair goals, locate your nearest salon and book in a treatment today.

Loved our guide to hair types? Keep reading to discover how to repair damaged hair.

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Far more than the place to get your root touch-up or an occasional trim, book an appointment at your nearest Kérastase salon for a complimentary personalized hair diagnosis.

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