What is the approximate width of a human hair?

• A. 20-40 microns
• B. 2-4 microns
• C. 80-100 microns
• D. 1-2 millimeters

Answer: (C)

Widths of everyday biological materials like human hair are often described in micrometers, placing hair diameter in the tens to hundreds of micrometers range. A typical hair is about 0.08 millimeters wide, which is 80 micrometers, so the 80–100 micrometers range is the best approximate. This matches the common scale used for hair thickness and helps distinguish it from much thinner particles (a few micrometers) or much thicker objects (millimeters). The other options either describe sizes far too small or far too large for a typical human hair.