35 Hair Thickness Statistics: Breakage, Hair Loss, and Hair Restoration

Hair thickness, or hair diameter, refers to the width of a single hair strand. Many confuse "hair thickness" with "hair density," but they mean different things.

Hair density is the total number of hair strands on your scalp, which is about quantity. More strands mean higher density and usually fuller hair.

Both thickness and density affect how full your hair looks. Thickness varies among individuals and measures how wide each hair strand is.

We’ll explore the top statistics surrounding hair thickness and what you can do about getting fuller-looking hair!

Top 10 Hair Thickness Statistics

• Hairs thinner than 200 micrometers, like those of humans, horses, and bears, break by shearing. [Source: 4]
• By age 35, two-thirds of American men will notice some hair loss. By 50, about 85% of men will have significantly thinning hair. [Source: 12]
• Clinical experience and past studies suggest that Caucasian scalp hair is denser than Asian hair, but the individual hair strands are generally thinner. [Source: 11]
• Hair thickness and density contribute to the best scalp coverage around age 35. Hair thickness increases until age 45, while hair density peaks in the late twenties. [Source: 9]
• Men had significantly lower hair density than women in the vertex area, with about 19 fewer hairs per cm² (p<0.001) in 2016. [Source: 5]
• About 55% of patients with pernicious anemia had gray hair before age 50, compared to 30% in the control group. [Source: 15]
• By the age of 50, about 50% of people will have half of their hair turned gray. [Source: 15]
• In people with patterned hair loss, both men and women had slower hair growth than those with average hair thickness. Men with pattern hair loss experienced even slower hair growth as their condition became more severe. [Source: 10]
• On average, total hair density ranges from 153 ± 30 hairs/cm² in South Africans to 233 ± 74 hairs/cm² in the French (p<0.001). [Source: 5]
• A 2024 study on hair thickness in Korean men with androgenetic alopecia found that average hair thickness decreased as the condition worsened. The thickest hair was in the V0 group (51-98 μm, average 70 ± 10 μm), and the thinnest hair was in the V3 group (24-65 μm, average 38 ± 8 μm). [Source: 6]

Aging Hair Statistics

Dr. Alan J. Bauman, MD, ABHRS, IAHRS, FISHRS, founder, CEO, & medical director at Bauman Medical in Boca Raton, FL, says, “As hair ages, we tend to torture it more, which makes matters worse. It’s not addressing the root of the problem. The problem is what encases the actual hair root: the follicle. The follicle function diminishes with age in proportion to hereditary risk.”

Gray hair is a common sign of aging, similar to wrinkles. Whether you embrace your gray hair, dye it, or something in between, it's natural to wonder why hair turns gray.

While graying is often linked to getting older, it doesn't always happen that way. Some people may go gray early, while others might never have gray hair. Various factors, including the environment and genetics, play a role.

Most women start to see gray hair in their 40s and 50s. Interestingly, genes and ethnicity primarily influence the likelihood of having gray hair at a certain age.

• In a study on hair color and greying, researchers found that between the ages of 45 and 65, 74% of people had grey hair, with an average intensity of 27%. [Source: 8] They further discovered:
  • Men had noticeably more grey hair than women. [Source: 8]
  • The age at which people start to get grey hair and how fast it happens seem connected to their ethnic or geographical background. Asians and Africans tend to have less grey hair than Caucasians of the same age. [Source: 8]

Changes in hair thickness as we age have a big impact on how old our hair looks. In 1988, Otsuka and Nemoto conducted the largest study on this topic, involving over 18,000 Japanese women aged 10 to 60. Their research found that hair thickness increases until age 40, then decreases, forming a curve rather than a straight line.

The second largest study by Robbins et al. looked at 1099 Caucasian women aged 18-66 who thought they were losing hair. It found that the age with the thickest hair diameter was between 43 and 46 years.

Otsuko and Nemoto found that scalp hair thickness peaks in Japanese men in their late teenage years and decreases quickly with age. Courtois et al., in their study of 10 men aged 25–49, showed that hair thickness starts to decrease from age 25.

• Hair thickness and density contribute to the best scalp coverage around age 35. Hair thickness increases until age 45, while hair density peaks in the late twenties. [Source: 9]

• Studies show that 6% to 23% of people have half of their hair turn gray by age 50. The age at which gray hair starts is influenced by genetics, including ethnicity and where a person is from. Asians and Africans tend to get gray hair later and have less of it than Caucasians, with average onset ages of 43.9 ± 10.3 years and 34 ± 9.6 years, respectively. [Source: 13]

Since gray hair is seen as a sign of aging, premature graying can negatively impact self-esteem.

• About 55% of patients with pernicious anemia had gray hair before age 50, compared to 30% in the control group. [Source: 15]
• By the age of 50, about 50% of people will have half of their hair turned gray. [Source: 15]

Hair loss and graying are the most common signs of aging hair, but other changes, like a decrease in hair thickness, are also significant.

Statistics by Hair Thickness in Males & Females

Men and women have different hair thicknesses, hair loss, and hair growth rates. Understanding hair thickness is important for both men and women because it affects hair health and style.

• Men had significantly lower hair density than women in the vertex area, with about 19 fewer hairs per cm² (p<0.001) in 2016. [Source: 5]

• In 2016, men had a slightly higher average Telogen percentage than women (12.2% vs 10.1%, p<0.001). The Telogen percentage also varies significantly across the three scalp areas for both men and women, with the highest values at the temple (p<0.001). [Source: 5]

• Men's hair grew slower at the nape by a few 0.1 mm per month compared to women (p<0.001) in 2016. For both genders, hair grows slightly faster on the vertex, by a few mm per year, compared to the nape and temple (p<0.001). [Source: 5]

• A 2024 study on hair thickness in Korean men with androgenetic alopecia found that average hair thickness decreased as the condition worsened. The thickest hair was in the V0 group (51-98 μm, average 70 ± 10 μm), and the thinnest hair was in the V3 group (24-65 μm, average 38 ± 8 μm). [Source: 6]

• A study by the National Library of Medicine looked at 59,765 anagen hairs (24,609 from controls and 35,156 from patients) and found that thinner hairs grow slower than thicker hairs. [Source 10] They also found:

  • Luteinizing Hormone/Gonadotropin-Releasing Hormone (LHGR) in healthy women was usually higher than in healthy men. [Source: 10]
  • LHGR is linked to hair thickness (P < 0.006), and overall thinning is related to slower hair growth. [Source: 10]
  • In people with patterned hair loss, both men and women had slower hair growth than those with average hair thickness. Men with pattern hair loss experienced even slower hair growth as their condition became more severe. [Source: 10]

• In the study of Ghanaian hair, researchers discovered the following:

  • The pubic hair shaft was the thickest in male and female participants, measuring 100.21 µm and 88.40 µm, respectively. [Source: 14]
  • The thickness of eyebrow hair was the smallest, with shaft diameters of 53.97 µm in males and 46.69 µm in females. [Source: 14]
  • The thickness of the axillary (underarm) and scalp hair is similar. In men, the thickness is 76.21 µm for axillary hair and 72.02 µm for scalp hair. In women, it is 73.07 µm for axillary hair and 71.15 µm for scalp hair. [Source: 14]

Men's hair is usually less dense and grows more slowly in some parts of the head than women's. Different parts of the body have different hair thicknesses. For both men and women, pubic hair is the thickest, and eyebrow hair is the lightest. Hormonal levels and diseases like androgenetic alopecia can also change how hair behaves. Knowing about these differences can help treat hair problems more effectively.

We suggest trying out our hair transplant treatment for fuller-looking hair. Our Sapphire FUE Method is an improved version of traditional FUE, where hair follicles are transplanted from the lower back of the head to areas with hair loss. The fine sapphire blades create precise V-shaped microchannels, leading to shorter healing times and denser hair growth.

Global Hair Thickness Statistics

In addition to making us look good, hair is very important to our health and has many valuable functions. Understanding how thick hair is in different parts of the world helps to recognize how different human hair is. Different groups have very different hair thicknesses, ranging from fine to coarse.

• Hairs thinner than 200 micrometers, like those of humans, horses, and bears, break by shearing. [Source: 4]

Wen Yang, a nanoengineering researcher at the University of California San Diego, explains: "Shearing is when small zig-zag cracks are formed within the material due to stress. These cracks then propagate, and for some biological materials, the sample isn't completely broken until the small cracks meet. If a material shears, it can withstand greater tension and thus is tougher than a material that experiences a normal fracture.”

• By age 35, two-thirds of American men will notice some hair loss. By 50, about 85% of men will have significantly thinning hair. [Source: 12]

• A study on the diversity of human hair found differences in growth, thickness, color, and shape in 2016. In addition, they found that:
  • On average, total hair density ranges from 153 ± 30 hairs/cm² in South Africans to 233 ± 74 hairs/cm² in the French (p<0.001). [Source: 5]
  • Globally, the percentage of Telogen hair ranged from 8 ± 6% in Danish people to 14 ± 7% in Thai people (p<0.001), which is within the normal range for hair renewal. [Source: 5]
  • The average hair growth rate varied from 272 ± 37 μm per day in South Africans to 426 ± 39 μm per day in Koreans, with a statistically significant difference (p<0.001). [Source: 5]
  • Hair diameter was measured in 823 volunteers (33% men and 67% women) from 15 African countries, the Americas, Asia, and Europe. The median hair diameter ranged from 69 ± 8 μm (French) to 89 ± 7 μm (Chinese) (p<0.001), showing the common trend of thicker hair among Asians. [Source: 5]

Genetics greatly affect the thickness of human hair strands. The EDAR gene on chromosome 2 is important for hair and skin development before birth. This gene provides instructions for making a protein that influences hair thickness. A variation of the EDAR gene, which appeared about 30,000 years ago, gives some people thicker hair strands. [Source: 7]

• Over 90% of Han Chinese, 70% of Japanese and Thai people, and 60% to 90% of Native Americans have the "thick hair strand" version of the EDAR gene. In contrast, this version is almost nonexistent in people of African and European descent. [Source: 7]
• Clinical experience and past studies suggest that Caucasian scalp hair is denser than Asian hair, but the individual hair strands are generally thinner. [Source: 11]

Genes and race are two things that can change how thick and how much hair someone has. Scientists have found that people have very different types of hair. This understanding helps explain how hair types differ and allows us to decide the best way to treat and care for our hair. We can better deal with problems like hair loss and develop specific ways to keep our hair healthy and strong as we learn more about how genes and our environment affect our hair.

Frequently asked questions

How thick is a human hair?

• Hair thickness varies widely among individuals, typically 18 to 180 microns, with an average thickness of about 100 microns. [Source: 1]

Which factors determine the thickness of human hair?

• Genetics: Your hair thickness is mainly determined by genetics. If your family has a specific hair type, you likely have it too. While genetics play a big role, it's not a certainty, as traits can vary and sometimes skip generations.
• Health: Your health affects hair thickness. A healthy lifestyle and good nutrition lead to thicker hair. Illnesses like chemotherapy and pregnancy can temporarily thin hair due to the body's redirected resources.
• Environmental Conditions: Environmental factors like sun exposure, chemicals, and heat styling impact hair thickness. People in sunnier regions have thicker hair due to more melanin, while overexposure and treatments can make hair finer. [Source: 2]

How can the thickness of human hair be measured?

• The Grip Technique: This simple method won't give exact numbers but provides a rough idea of hair thickness. Ideal for those new to hair types, you pluck a strand and roll it between your thumb and index finger. If you can't feel it, you have fine hair. If you feel it strongly, your hair is thicker than average. If you can feel it but it's not prominent, your hair thickness is average.
• The Thread Technique: To estimate hair thickness, compare a plucked hair strand to a thread. Place the hair on paper, then stretch a thread next to it. If your hair is thinner than the thread, you have fine or normal hair, depending on the difference. If it's thicker, you have very thick hair. Knowing the thread's thickness can give you an approximate measurement.
• The Laser Technique: This is the most accurate but involves calculations. Shine a laser pointer on a hair strand stuck to a cardboard frame with a hole. Measure the diffracted light on a screen and the distance between the screen and the hair, and use the light's wavelength (printed on the laser device). These measurements go into a formula to determine hair thickness. A video can provide detailed instructions and the formula. [Source: 2]

Is thick hair stronger than fine hair?

• Yes, thick hair contains three different layers, adding to its strength. Fine hair carries only two layers, making it weak and prone to breaking and falling. Vellus hair is thin, weak, and can break with minimal force, while thick hair can withstand high pressure. [Source: 3]

What are the different layers of hair?

• Human hair comprises three layers, i.e., cortex, cuticle, and medulla. The cortical layer contains keratin filaments, while the cuticle protects against friction and radiation. The medulla layer is present in the thicker hair, which adds volume to the hair. [Source: 3]

Sources

1. [Source: 1] - Exploring How Thick is a Human Hair by The Knowledge Hub
2. [Source: 2] - The Thickness of Human Hair by Hair World Mag
3. [Source: 3] - Human Hair Thickness in 2024 by You Probably Need a Haircut
4. [Source: 4] - Thin Hair is Stronger Than Thick Hair by UC San Diego Jacobs School of Engineering
5. [Source: 5] - Diversity in human hair growth, diameter, colour and shape by European Journal of Dermatology
6. [Source: 6] - Quantitative measurement of hair diameter diversity as a diagnostic indicator of androgenetic alopecia in Korean males by JAAD International
7. [Source: 7] - Hair Strand Thickness by Ancestry DNA
8. [Source: 8] - Greying of the human hair by National Library of Medicine
9. [Source: 9] - A Comment on the Science of Hair Aging by International Journal of Trichology
10. [Source: 10] - Gender differences in scalp hair growth rates by National Library of Medicine
11. [Source: 11] - Assessment of hair density and caliber in Caucasian and Asian female subjects by Journal of American Academy of Dermatology
12. [Source: 12] - Men’s Hair Loss by American Hair Loss Association
13. [Source: 13] - Hair Aging and Hair Disorders in Elderly Patients by International Journal of Trichology
14. [Source: 14] - Light Microscopic Morphology of Indigenous Ghanaian African Hair by International Journal of Trichology
15. [Source: 15] - Premature Graying of Hair by International Journal of Trichology