What is The Diameter of a Human Hair In Inches? (All Facts and Figures)

what is the diameter of a human hair in inches

Human hair is quite a delicate and thread-like structure. Their thickness, color, and length can tell you which style suits your personality. Do you have a chance to check the diameter of your hair?

Or have a question in your mind:

What is the diameter of a human hair in inches? Perhaps you will be confused and think, how can we calculate the diameter of such a tiny and fragile thing.

Don’t worry scientists measure the accurate diameter of human hair.

The diameter of human hair is 0.001 to 0.004 inches. If we want to calculate it in feet divide this by 12(0.00254 cm).

The diversity of the diameter of human hair depends on age, gender, ethnicity, and type of hair.

What is The Diameter of a Human Hair in Inches

 The Skin Biopsy is one of the intrusive methods for finding the hair parameter. However, it is not the preferred choice for hair and scalp because it causes pain and scars

Alternative simple and easy methods are Wash test, Trichoscopy and Phototrichogram are more fit. Quantitative trichoscopy analysis in the form of Videodermscopy combined with an image analysis system gives an accurate measurement of human hair

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With the help of the above technology, it is found that the diameter of human hair is 0.004 inches but not all the hair of a man has the same diameter on all parts of the head. There is a slight variation in size

Now laser light is also used to determine the diameter of the hair.

What Is The Average Diameter of Human Hair

The thickness of hair in different geological areas is different for different races. hair diameter varies across the continent and also in different races.

The thinnest is around two-thousandth of an inch in diameter. The thickest can be measured at about six thousandths. The overall average diameter is 0.0038 inches. This is equal to 0.00033 feet.

What Is the Difference In Hair Diameter Between Male and Females

Hair densities and diameter are not affected due to gender. Both males and females have almost equal or slightly varying diameters. The hypothesis that hormones are not involved in the development and functioning of hair follicles or keratinization of the hair shaft is the result of a lot of research.

This condition is not correct in the case of Androgenetic alopecia(AGA). A patient suffering from AGA and females suffering from FPHL hair density and hair diameter decreases differently. These illnesses originate genetically.

Comparisons of hair density and hair diameter between males and females:

Scalp siteHair density male(hairs/cm)Hair density female (hair/cm2)p-valueHair diameterFemaleinchesHair diameter male inchesP-value

Scalp Areas and Human Hair Diameter

The largest hair diameter of hair is discovered on the frontal side of the scalp, but this is not statistically big different from the hair in the other places. These findings were uniform in both males and females. The reduction diameter occurs on the temporal and occipital sides.

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The highest density is observed on the frontal and the lowest density can be seen in temporoparietal areas.

Variation of Diameter of Human Hair In Different Ethnicity

Diversity of hair density and hair diameter can be found in different races. The hair diameter is different in Asians from those in Caucasian, African, and Hispanic populations.

Racial factors and genetic background are the main agents that decide how thick the hair should be.

Hair density and diameter in Asian people are distinctive. In China and Korea hair density is low but in Africa, it is strong and thick. The local environment, diet, genetics, and exposure to the sun also determine the hair thickness.

Age Factor and Thickness of Hair

Age is considered an important factor in the density of hair. With increasing age hair follicles are weak and the ability to produce new hair falls rapidly.

 Japanese and Chinese women after forty show a great difference in hair density. Detailed studies show that the volume of hair reduces due to hair fall and the deactivation of hair follicles. But surprisingly hair diameter is not so much affected.

Main Reason for variation in Diameter in Human Hair

There has been a belief that man’s hair diameter is dictated by distinctive genes that vary among different ethnicities. The hair diameter in Asians is deeply confined by ectodysplasin-A receptor gene variance. Those with CC genotypes would have a greater hair diameter with bigger cross-sectional areas than those with TC and TT genotypes.

Hair Types and Diameter of Human Hair

Fine hair has a small diameter that is measured at 0.0019 inches. Straight thick hair has medium value. But coarse hair shows a bigger cross-sectional area. Its diameter is 0.0047 inches, bigger than the width of paper which is 0.0024 inches.

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The diameter of human hair range from 0.000669 inches to 0.007125 inches.

Frequently Asked Question

Is it normal for hair to differ in thickness?

Hair diameter changes slightly from person to person and tends to differ by ethnicity. There’s no such thing as a hair density that’s too high or too low, and your hair density isn’t indicative of your overall health. However, people with nutritional deficiencies may experience hair loss that reduces overall hair density.

Should Hair Be The Same Thickness all Over?

All hair on the scalp has a slightly different measurement, and caliber unless the person is affected by AGA or TE. But color and density may change in different parts of the scalp with age, a diet deficiency, and physical factors like sun exposure.

What is The Effect of Miniaturization of Hair on The Diameter of Human Hair?

Hair follicle miniaturization is a technical term for hair thinning in diameter, hair fall, or balding. In this process mostly men face the constriction of hair follicles making hair weak and stunting growth. This receding hairline, thinner hair on the top, and bald spot. Hair diameter reduces by 20% in volume in hair miniaturization.


Hair is found on all parts of our body except the palm, the pink part of our lips, and the lower side of the foot. But their size, length, and thickness vary in all parts. People with thick hair considered the diameter of their hair to be greater than others. It is not true. It is a type of hair like the diameter of fine hair is always less than coarse.

 The diameter measured by scientists is from 0.00067 to 0.00709 inches and its average is .0038 to 0.004 inches.

 All this information may be helpful in understanding hair structure, health, and formation so please share this with others.

James Randolph

Hey, James is here with you. This blog is a powerful online resource to help you get instant answers to your superstitious beliefs, facts, and the reality of myths. Knowledge is your inner guidance system, and this blog empowers you to update, refine, reorganize and enhance your communication system. If you know well you can surely discuss facts with evidence. So, stay with us and be a master of what happens around you!

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