Body Fat (U.S. Navy Method) Calculator
Estimate body-fat percentage from tape measurements using the U.S. Navy circumference formula — no calipers or scales required.
How it works
Men: %BF = 495 ÷ (1.0324 − 0.19077·log₁₀(waist−neck) + 0.15456·log₁₀(height)) − 450 · Women: %BF = 495 ÷ (1.29579 − 0.35004·log₁₀(waist+hip−neck) + 0.22100·log₁₀(height)) − 450 (all in cm)
The U.S. Navy method estimates body fat from body circumferences alone, because fat and lean tissue distribute differently around the waist, neck and hips. It needs only a tape measure, which is why the military uses it for large-scale screening. It is less precise than a DEXA scan but usually lands within a few points for average builds.
Worked example
A man 178 cm tall with a 38 cm neck and 90 cm waist has waist−neck = 52 cm. The formula gives 495 ÷ (1.0324 − 0.19077·log₁₀52 + 0.15456·log₁₀178) − 450 ≈ 495 ÷ 1.0529 − 450 ≈ 20.1% body fat — the average range.
Sources: U.S. Navy body fat formula
Frequently asked questions
How accurate is the Navy method?
For typical body shapes it is usually within about 3–4 percentage points of a DEXA scan. It can over- or under-estimate for very muscular or very lean people, since it infers fat from girths rather than measuring it directly.
Why do women need a hip measurement?
Women store proportionally more fat around the hips, so the female formula adds hip circumference to capture that distribution. The male formula uses only neck and waist.
How should I take the measurements?
Measure relaxed, without pulling the tape tight, over bare skin. Men measure the waist at the navel; women at the narrowest point. Take each measurement two or three times and average them.
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Educational estimate only — not medical advice, diagnosis or treatment. Consult a qualified clinician for health decisions.