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Fine, Medium or Coarse Hair Test

Take this fine, medium or coarse hair test: five quick checks on a single strand, including the thread test, show your strand thickness and what it changes.

Question 1 of 5

Lay one strand next to a piece of sewing thread. Your strand is…

Use a clean shed hair and ordinary all-purpose thread, on a surface that contrasts with your hair color.

How to use the Fine, Medium or Coarse Hair Test

  1. Collect one clean strand and a piece of thread

    Take a shed hair from your comb, free of product, and a piece of ordinary sewing thread. A sheet of paper that contrasts with your hair color helps.

  2. Do the thread and finger checks

    Lay the strand next to the thread and compare the width, then roll it between your thumb and finger and note how much you can feel.

  3. Answer the questions about styling

    Tell the test how easy the strand is to see, how your styles hold, and how your hair reacts to heat and rich products.

  4. Read your result

    You get fine, medium or coarse, a note if your answers were mixed, and what it changes for heat, product weight and protective-style tension.

How to use the Fine, Medium or Coarse Hair Test (58 s)

How the fine, medium or coarse hair test works

Strand thickness, also called hair texture or width, is how wide one single hair is. It is separate from your curl pattern and from how much hair you have. The test asks five things you can check at home in a couple of minutes.

The five checks

Two checks look at the strand directly: comparing it with a piece of sewing thread, and rolling it between your thumb and finger. Three checks look at how your hair behaves: how easy one strand is to see against a contrasting background, how well styles hold, and how your hair responds to heat and to rich products. Use a clean shed hair, because product coats the strand and makes it feel thicker.

How the answers are scored

Every answer votes fine, medium or coarse. The two direct checks count double, because they depend less on your routine. A fine answer subtracts its weight, a coarse answer adds it, and a medium answer adds nothing. 

score = coarse points − fine points   (from −7 to +7)
fine: −3 or lower · coarse: +3 or higher · medium: in between

If fine and coarse answers each collect at least 2 points, the result is flagged as mixed. That usually means your strands differ from one part of your head to another, which is common: the hairline and nape are often finer than the crown.

What strand thickness changes

Thickness sets how much heat a strand can take, how much product it can carry and how much pull it can stand. Fine strands heat through fast and break under less force, so they need lower temperatures, lighter products and lighter protective styles. Coarse strands are stronger and hold styles longer, but they often feel dry and need richer products. The heat ranges in the result come straight from the flat iron temperature guide, so the two tools always agree.

What the test cannot tell you

It does not measure anything. The diameters in the chart below are commonly quoted, approximate ranges, and studies of hair from around the world show a wide, overlapping spread. The test also says nothing about density, which is the number of strands on your scalp — check that with the hair density test — or about porosity, which you can check with the hair porosity test.

Fine vs medium vs coarse hair chart

Strand thickness Approx. diameter Flat iron range Products Protective styles
Fine under about 60 µm 320–360 °F (160–180 °C) Choose light products: milks, lotions, foams and light oils. Keep protective styles light: medium or large parts, shorter lengths and less added hair.
Medium about 60–80 µm 360–400 °F (180–205 °C) Most product weights work. Most braid and twist sizes work.
Coarse over about 80 µm 400–425 °F (205–220 °C) Use richer products: creamy leave-ins, butters and heavier oils to soften the strand and hold moisture in. Thicker strands are stronger, but your scalp is not.

Diameters are commonly quoted rules of thumb in microns (µm), not cut-offs from a standard. Flat iron ranges are for healthy coily hair, ceramic plates and heat protectant.

The five checks at a glance

Check Points to fine Points to coarse Weight
Lay one strand next to a piece of sewing thread. Your strand is… Clearly thinner than the thread As thick as the thread or thicker Counts double
Roll one strand between your thumb and finger. What do you feel? Almost nothing I can feel it clearly Counts double
Hold one strand against a contrasting background. How easy is it to see? Hard to see It stands out as a bold line Counts once
How do your styles hold? They slip, go limp or fall out quickly They hold for days and resist being reshaped Counts once
How does your hair respond to heat and to rich products? It straightens fast on low heat It needs more heat or extra passes Counts once

Frequently asked questions

How do I know if my hair is fine, medium or coarse?
Look at one strand, not the whole head. Compare a clean shed hair with a piece of sewing thread and roll it between your fingers. A strand that is much thinner than the thread and hard to feel is fine, one you can feel clearly and that looks sturdy is coarse, and anything in between is medium. This fine, medium or coarse hair test adds three more signs to make the call steadier.

Is coarse hair the same as thick hair?
No. Coarse describes the width of each strand. Thick usually describes density, which is how many strands you have. You can have fine strands and a lot of them, or coarse strands and few. Use the hair density test to check the second part.

Is 4c hair always coarse?
No. Curl pattern and strand thickness are separate traits. Many people with tightly coiled hair have fine strands, which is one reason coily hair can be fragile even when it looks full. Measured strand diameter varies widely within every hair type.

How accurate is the thread test?
It is a rough comparison, not a measurement. Sewing thread varies in width, and strands differ across your head. That is why the test combines the thread check with feel, visibility and how your hair behaves. Only a microscope or a micrometer gives an actual diameter.

Can my hair be fine in one area and coarse in another?
Yes. The hairline and nape are often finer than the crown. If your answers split, the result is marked as mixed and you are asked to repeat the checks with strands from two or three areas.

What flat iron temperature should I use for fine hair?
Lower than you think. For healthy coily hair with heat protectant the starting range is 320–360 °F for fine strands, compared with 400–425 °F for coarse ones. Color-treated, relaxed or damaged hair needs less. The flat iron temperature guide adjusts the range for your hair.

Can I change my strand thickness?
Not with products. Strand width is set in the follicle. It can change with age, hormones and health, and products can only coat the strand so it feels thicker for a while. If your hair has become noticeably thinner in a short time, see a board-certified dermatologist.

Sources

Last data update:

  1. Loussouarn G, Lozano I, Panhard S, et al. Diversity in human hair growth, diameter, colour and shape. An in vivo study on young adults from 24 different ethnic groups observed in the five continents. Eur J Dermatol. 2016;26(2):144-154. Growth rate, diameter and curl shape vary widely between and within groups.
  2. Robbins CR. Chemical and Physical Behavior of Human Hair. 5th ed. Springer; 2012. Reference text on hair structure, surfactants, conditioning agents, protein, heat and chemical treatments.

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