Body composition calculator
Body fat calculator
Estimate your body-fat percentage with a tape measure — no calipers, no scales. The US Navy method. Free, instant, no sign-up.
Track this number — the trend says more than today's reading.
Free — no card, 30 seconds. Your result comes with you.
What is the Navy body-fat method?
The US Navy circumference method estimates body-fat percentage from a few tape measurements — neck, waist, and (for women) hips — plus your height. No calipers, no scales, no lab. It's an accessible estimate you can do at home in two minutes.
How this calculator works
It fits a logarithmic regression to measurements in centimetres using base-10 logs. For men: 495 / (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450. For women, hip circumference is added into the waist term. Measure the waist at the navel and the neck just below the larynx for the most consistent reading.
How to use the number
Treat this as a population-fit estimate, not a DEXA scan — it's most valuable for tracking a trend over weeks, not as a single absolute number. Measure under the same conditions each time. The coach can build a cut or recomp around your number and re-check it as you go.