Body Fat Calculator

All you need is a tape measure: enter your neck and waist to estimate your body fat percentage.

Men: at the navel. Women: at the narrowest point
Needed for women only

Results

Body fat
16.94%
Category
Fitness
Fat mass (kg)
12.7
Lean body mass (kg)
62.3

Uses the U.S. Navy circumference method, accurate to about ±3–4%. Keep the tape snug but not tight, and measure at the same time of day.

Body fat percentage is the share of your total weight that is fat. Scales only tell you the total; body fat tells you what that total is made of. Two people at the same weight can have very different percentages.

This calculator uses the circumference method developed by the U.S. Navy. No special device is needed — height, neck and waist (plus hips for women) are enough.

How to calculate Body fat

  1. Choose your sex and enter your height and weight.
  2. Measure your neck just below the larynx.
  3. Measure your waist at the navel (men) or at the narrowest point (women); women also measure the hips at the widest point.

Body fat formula

  • Men: 495 ÷ (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450
  • Women: 495 ÷ (1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)) − 450
  • Fat mass = weight × body fat %; lean mass = weight − fat mass

Body fat example

A man 175 cm tall with a 38 cm neck and an 85 cm waist comes out at about 16.9% body fat. At 75 kg that is 12.7 kg of fat and 62.3 kg of lean mass.

Body fat: common questions

What is a healthy body fat percentage?

Commonly quoted ranges are 14–24% for men and 21–31% for women. Athletes sit lower. Women naturally carry more essential fat.

How accurate is this method?

With careful measuring it is within about ±3–4%. It is less precise than a DEXA scan but good enough to track change over time.

How do I measure consistently?

Measure at the same time of day, ideally in the morning. Keep the tape level, touching the skin without compressing it.