What is the approximate average width of a human hair?

• A. 60-70 microns
• B. 40-60 microns
• C. 100-120 microns
• D. 80-100 microns

Answer: (D)

Diameter of human hair is typically measured in micrometers and varies with hair type and person. A practical average for adult scalp hair falls around tens of micrometers, with many hairs clustering near the 70–90 µm range. When rounded to a simple average across populations, 80–100 µm captures this general magnitude, making it the best choice here. A width of 40–60 µm would be noticeably thinner than most hairs; 60–70 µm is already narrower than the common midpoint; 100–120 µm sits on the thicker end and is less representative of the typical average. Therefore, 80–100 micrometers is the most reasonable approximate average.