Scale Explorer

Microscopic

How big is the width of a human hair?

Human hair (width) · Cross-section of a single strand

Average diameter
≈ 70 µm 0.0028 in approx.
Diameter range
17–181 µm 0.00067–0.0071 in range
Show
Human hair (width), Grain of sand, Ant (black garden ant), Human drawn to the same scaleHuman hair (width): average diameter ≈ 70 µm (too small to see at this scale). Grain of sand: grain diameter (sand size class) 0.0625–2 mm (too small to see at this scale). Ant (black garden ant): length (worker) 3.4–5 mm (too small to see at this scale). Human: height 1.61–1.75 m.Human hair (width): ≈ 70 µm (too small to see at this scale)Grain of sand: 0.0625–2 mm (too small to see at this scale)Ant (black garden ant): 3.4–5 mm (too small to see at this scale)Human: 1.61–1.75 mHuman1.61–1.75 mHuman hair (width)≈ 70 µm · too small to seeGrain of sand0.0625–2 mm · too small to seeAnt (black garden ant)3.4–5 mm · too small to see

Human hair (width), Grain of sand and Ant (black garden ant) are too small to see at this scale and are marked with ▲.

Everything is drawn to the same scale, standing on the same ground line. Silhouettes are simplified outlines scaled to the measured dimension. A faded outline shows the top of a size range.

Compare Human hair (width) with something else →

Dimensions

MeasurementMetricImperialNotesSource
Average diameter ≈ 70 µm ≈ 0.0028 in Average human hair width used by the EPA for particle-size comparisons. Approximate [1]
Diameter range 17–181 µm 0.00067–0.0071 in From fine flaxen hair (1/1500 in) to coarse black hair (1/140 in). Range: varies [2]

About the width of a human hair

The width of a human hair is a common everyday yardstick for very small things. Hair thickness varies a great deal between people and hair types, with fine light hair at the thin end and coarse dark hair at the thick end. The US Environmental Protection Agency uses an average of about 70 micrometres when comparing hair with airborne particles.

  • According to the EPA, an average human hair is about 30 times wider than the largest fine particle (PM2.5). [1]
  • Flaxen hair is the finest, about 1/1500 to 1/500 of an inch across, while black hair is the coarsest, about 1/450 to 1/140 of an inch. [2]

How many fit?

  • ≈ 24,000 × Human hair (width) · average diameter lined up end to end match the Human · height
  • ≈ 1–29 × Human hair (width) · average diameter lined up end to end match the Grain of sand · grain diameter (sand size class)

Counts divide one sourced figure by another. "End to end" uses each object's main measurement; weight and volume rows appear only when both figures are sourced.

How it compares

  • 0–1.1× The width of a human hair is roughly as wide as a grain of sand: between 0 and 1.1 times as wide, depending on size. See side by side
  • 1/49–71 A black garden ant is about 49–71 times as long as the width of a human hair is wide. See side by side
  • 1/100 A grain of rice is about 100 times as long as the width of a human hair is wide. See side by side
  • 1/140–210 A honeybee is about 140–210 times as long as the width of a human hair is wide. See side by side
  • 1/270 A US penny is about 270 times as wide as the width of a human hair. See side by side
  • 1/24,000 An average adult is about 24,000 times as tall as the width of a human hair is wide. See side by side

Factors compare the average diameter of the width of a human hair with each object’s own main measurement (height for a human). Where a size varies, the factor is given as a range.

Notes on these figures

  • The 17 to 181 µm range in BioNumbers is drawn from The Physics Factbook (Glenn Elert), and BioNumbers itself notes that a better source is needed.
  • Hair width varies with ethnicity, age, colour and body site; the EPA figure is a rounded average for comparison, not a measurement study.

Sources

  1. U.S. Environmental Protection Agency, Particulate Matter (PM) Basics. Accessed 25 September 2026.
  2. BioNumbers, Harvard Medical School, Diameter of human hair - BNID 106856. Accessed 25 September 2026.

Related objects