A man, 178 cm and 80 kg
Neck 38 cm and waist 86 cm give about 17.2% body fat — the “Fitness” range for men (14–17%) — which is roughly 13.8 kg of fat mass.
Body Fat Calculator
Estimate body fat percentage from tape measurements with the US Navy method, in metric or US units.
Result
Enter your values and select Calculate to see the result.
Result
Enter your values and select Calculate to see the result.
Runs in your browser — nothing you enter is sent to a server.
How the Body Fat Calculator works
The US Navy method estimates body fat from a few tape measurements and your height. Measure your neck just below the larynx and your waist (at the navel for men, at the narrowest point for women); women also measure the hips at the widest point. Add your weight to see fat mass and lean mass. The category uses the American Council on Exercise (ACE) ranges.
Formulas
Men (centimetres)
body fat % = 495 ÷ (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450
Women (centimetres)
body fat % = 495 ÷ (1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)) − 450
US measurements are converted to centimetres first (1 in = 2.54 cm).
Examples
ACE ranges
Men: essential fat 2–5%, athletes 6–13%, fitness 14–17%, average 18–24%, obese 25% and over. Women: 10–13%, 14–20%, 21–24%, 25–31% and 32% and over.
Frequently asked questions
How accurate is the Navy method?
It's usually within a few percentage points of lab methods such as DEXA, but careful, consistent measuring matters most. Measure three times and use the average.
Why is body fat more useful than BMI?
BMI uses only height and weight, so muscular people can look “overweight”. Body fat looks at composition — though it is still an estimate.
Are my measurements stored?
No. The calculation runs in your browser and nothing is sent or saved.
Information:
Good to know
For general information only — not medical advice, diagnosis or treatment. Talk to a doctor or other qualified professional about your health.
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