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Body fat calculator

All you need is a tape measure: estimate your body fat percentage from a few body measurements using the US Navy method.

Sex
 

Measure the neck below the larynx, the waist at the navel (men) or at the narrowest point (women), and the hips at the widest point.

Body fat
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AthletesFitnessAverageObese
Fat mass
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Lean mass
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How to use the body fat calculator

  1. Choose your sex and units.
  2. Measure your height, neck and waist – and, for women, your hips.
  3. Optionally add your weight to see your fat mass and lean mass.

Measure in the morning, standing relaxed, with the tape snug but not pressing into the skin. Neck: just below the larynx. Waist: at the navel for men, at the narrowest point for women. Hips: at the widest point.

The US Navy 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

All measurements are in centimetres; the calculator converts inches for you.

Worked examples

A man who is 180 cm tall with a 38 cm neck and 85 cm waist has about 16.1% body fat. A woman who is 165 cm tall with a 33 cm neck, 75 cm waist and 98 cm hips has about 28.4%.

Body fat categories

CategoryMenWomen
Essential fat2–5%10–13%
Athletes6–13%14–20%
Fitness14–17%21–24%
Average18–24%25–31%
Obese25% and above32% and above

Categories from the American Council on Exercise (ACE).

The tape-measure method is an estimate, typically within 3–4 percentage points of lab methods such as DEXA scans. For tracking progress, measure the same way each time and watch the trend.

Frequently asked questions

Is body fat percentage better than BMI?
It tells you more about body composition. BMI only uses height and weight, so muscular people can have a “high” BMI with low body fat. Body fat percentage separates fat from lean mass.
How accurate is the US Navy method?
For most people it is within about 3–4 percentage points of a DEXA scan. Careful, consistent measuring matters more than the formula.
What is a healthy body fat percentage?
Roughly 14–24% for men and 21–31% for women falls in the fitness and average ranges. Very low values are not healthier – some essential fat is needed.

Last reviewed: November 13, 2026

Results are estimates for general information only and are not financial, tax, medical or legal advice. Check important figures with a qualified professional.