Body Fat Percentage Calculator
Estimate your body fat percentage using the US Navy method.
Precision Fitness Calculators
Estimate your body fat percentage using the US Navy method.
cm
cm
Around the narrowest point
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At the navel level
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Scientific Reference
This calculator uses the U.S. Navy Circumference Method, developed by Hodgdon and Beckett at the Naval Health Research Center (1984). It estimates body fat percentage from simple tape measurements.
The Formulas
- Men: 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
- Women: 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
Body Fat Categories (Male / Female)
- Essential Fat: 2–5% / 10–13%
- Athletes: 6–13% / 14–20%
- Fitness: 14–17% / 21–24%
- Average: 18–24% / 25–31%
- Obese: 25%+ / 32%+
How the US Navy method works
Developed by Hodgdon and Beckett at the Naval Health Research Center in 1984, the circumference method estimates body fat from simple tape measurements — height, neck and waist for men, plus hips for women — using logarithmic regression equations validated against underwater weighing. The US military still uses it for fitness assessments because it is fast, cheap and repeatable.
Against DEXA scans, the Navy method typically lands within 3–4 percentage points for most physiques. That is not laboratory precision, but it is more than accurate enough to classify your range and — more importantly — to track change over time, since the tape errors are consistent from month to month.
Measuring correctly and reading your result
Measure in the morning before eating, with a flexible tape held snug but not compressing the skin. Waist: at the navel for men, at the narrowest point for women, at the end of a normal exhale — no sucking in. Neck: just below the larynx, tape sloping slightly downward at the front. Hips (women): at the widest point. Take each measurement twice and average.
Ranges for men and women differ because women carry essential fat for hormonal function: essential fat is 2–5% for men and 10–13% for women, athletes typically sit at 6–13% and 14–20%, the fitness range at 14–17% and 21–24%, and average at 18–24% and 25–31%. For fat loss, aim to move one range at a time — chasing single-digit body fat is neither necessary nor sustainable for most desk workers; the health payoff comes from getting out of the obese range and keeping muscle while you do it.
Body fat percentage is also the number that makes body recomposition visible. If you are eating at a modest deficit and lifting, the scale can sit still for weeks while you simultaneously lose fat and add muscle — a result that looks like failure on a bathroom scale and like success on a tape measure. Tracking body fat alongside weight separates those two stories. Expect roughly 0.5–1 percentage point of change per month at a sustainable deficit; anything faster usually means you are losing muscle too, which lowers your TDEE and makes the next phase harder.
Frequently Asked Questions
How accurate is the US Navy body fat method?
Studies comparing it to DEXA scans put it within roughly 3–4 percentage points for most people. Its real strength is tracking: measured the same way each time, it reliably shows whether body fat is going up or down.
What is a healthy body fat percentage?
For men, 10–20% covers the athletic-to-average healthy span; for women, 18–28%. Women need higher essential fat for hormonal health. Health risk rises meaningfully above 25% for men and 32% for women.
When should I measure body fat?
Morning, before food or water, at the same time each measurement. Re-measure every 2–4 weeks — body fat changes slowly, and measuring more often mostly captures tape-placement noise rather than real change.
Why does the female formula need a hip measurement?
Women predominantly store fat around the hips and thighs (gynoid pattern), while men store it abdominally. Adding the hip circumference lets the regression capture that distribution, which is why the two equations differ.