FIA Hair Typing: System combining curl type, strand thickness, and volume

What is FIA Hair Typing?

FIA Hair Typing is a detailed classification system that categorizes hair based on its curl pattern, texture, and density. It expands on simpler systems to give you a more precise understanding of your hair’s unique blueprint. Most people don’t realize that this system also considers your hair’s thickness and overall volume, not just the shape of your curls.

This framework helps you decode what your hair truly needs to look and feel its best.

How FIA Hair Typing Decodes Your Curl Pattern

Your curl pattern is determined by the shape of your hair follicle. Think of a straight follicle like a round tube producing straight hair, while a curved or oval-shaped follicle creates bends and curls.

The more oval the follicle, the tighter the curl spring. I often see patients who are frustrated because they’re using products meant for a different curl type, which leads to constant bad hair days.

Understanding this biological basis is the first step to choosing the right routine.

Why FIA Hair Typing Includes Texture and Density

FIA Hair Typing goes beyond just curl shape by including your hair’s thickness and how many strands you have per square inch. Your hair’s texture refers to the width of a single strand—whether it’s fine, medium, or coarse.

Density is about how many of those strands are packed on your scalp. A head of fine hair can feel incredibly thick if the density is high. This is a crucial distinction most at-home quizzes miss completely.

In my clinic, I find that nearly 80% of clients with fine, high-density hair mistakenly treat it as coarse, weighing it down with heavy products.

When Your FIA Hair Type Changes

Your FIA type isn’t always set in stone. Hormonal shifts, like those during pregnancy or menopause, can alter your curl pattern and texture by changing your follicle’s shape and output.

Medical conditions and certain medications can also have a dramatic impact. I always ask new patients about recent health changes, not just their product history, as the root cause of hair complaints often lies here.

Think of your hair type as a current weather report, not a fixed genetic destiny.

The Biggest FIA Hair Typing Mistake I See

The most common error is focusing only on the curl category while ignoring texture and density. This leads to a flawed product selection that never delivers the promised results.

For example, a Type 4 coily pattern with fine, low-density strands needs lightweight liquid moisturizers. A Type 4 coily pattern with coarse, high-density hair can handle heavier creams and butters.

Using the wrong one either causes greasy, limp hair or dry, brittle strands. I see this confusion causing breakage in my practice weekly.

From My Experience

After years of scalp analysis, I’ve observed a pattern I call “Porosity Primacy.” While your FIA type gives a great structural overview, your hair’s porosity—its ability to absorb and hold moisture—is the ultimate dictator of product performance.

A low-porosity Type 3 curl will reject heavy oils that a high-porosity Type 3 curl desperately needs. I advise my clients to determine their FIA type first to understand structure, then do a porosity test to master moisture management. This two-step approach eliminates nearly all guesswork.

Your hair’s behavior is a perfect conversation between its structure (FIA type) and its function (porosity). Listening to both is the secret to truly healthy hair.