Man: Navy method estimate
- Input
- Man, Height = 70 in, Waist = 34 in, Neck = 15 in
- Working
- 86.010×log10(34 − 15) − 70.041×log10(70) + 36.76 = 86.010×log10(19) − 70.041×log10(70) + 36.76, which evaluates to 17.5%.
- Result
- Body fat = 17.5%
Body Fat Calculator
Estimate body fat percentage from tape measurements with the US Navy circumference method, and split body weight into fat mass and lean mass. Runs entirely in your browser — your numbers never leave this device.
Sex
Measurement unit
Body fat percentage
17.5%
- Fat mass
- 31.5 lb
- Lean mass
- 148.5 lb
- Formula
- US Navy circumference method
Informational only. This calculator applies a published formula to the numbers you enter — it is not medical advice, a diagnosis, or a substitute for a clinician. Talk to a qualified professional about decisions concerning your health.
How it works
US Navy circumference method (inches, log10) — 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
The US Navy circumference method estimates body fat percentage from tape measurements and height, using the logarithmic equations the US Navy published for personnel assessments. For men the inputs are waist and neck circumference plus height; for women the equation adds hip circumference. All measurements are in inches in the published form, and the constants — 86.010, 70.041 and 36.76 for men; 163.205, 97.684 and 78.387 for women — are printed in the formula above.
Measurement position is part of the method. The published protocol measures the waist at the navel for men and at the narrowest point for women, the neck below the larynx, and the hip at its widest point, with the tape horizontal and snug without compressing the skin. Small differences in tape position change the circumferences and therefore the result, which is one reason the output is an estimate.
Circumference methods estimate composition indirectly. Laboratory methods such as DEXA scanning measure tissue directly and will not return the identical figure; skinfold and bioimpedance methods use different models again and also differ from one another. This page returns the Navy method's output for information only, and splits a given body weight into fat mass and lean mass by applying that percentage.
Worked examples
Same man: fat mass and lean mass at 180 lb
- Input
- Body weight = 180 lb, Body fat = 17.5%
- Working
- Fat mass = 180 × 0.175 = 31.5 lb. Lean mass = 180 − 31.5 = 148.5 lb.
- Result
- Fat mass = 31.5 lb · Lean mass = 148.5 lb
Woman: Navy method estimate and masses at 150 lb
- Input
- Woman, Height = 65 in, Waist = 28 in, Hip = 36 in, Neck = 12 in, Weight = 150 lb
- Working
- 163.205×log10(28 + 36 − 12) − 97.684×log10(65) − 78.387 = 163.205×log10(52) − 97.684×log10(65) − 78.387, which evaluates to 24.6%. Fat mass = 150 × 0.246 = 36.9 lb; lean mass = 150 − 36.9 = 113.1 lb.
- Result
- Body fat = 24.6% · Fat mass = 36.9 lb · Lean mass = 113.1 lb
Frequently asked questions
Where do the waist, neck and hip measurements go?
Following the published protocol: waist at the navel for men and at the narrowest point for women, neck below the larynx, and hip at the widest point, with the tape horizontal. Position affects the circumferences entered and therefore the result.
How does this compare with a DEXA scan?
They are different kinds of measurement. DEXA measures tissue directly with imaging; the Navy method estimates percentage from circumferences through a regression equation. The two will generally be close but not identical, and neither figure invalidates the other — they are outputs of different methods.
Why does the formula use logarithms?
Because the relationship between circumferences and measured body fat in the Navy's validation data was logarithmic rather than linear. The published equations use log base 10, and the constants printed on this page belong to that form with measurements in inches.
Is this a medical assessment?
No. It is an informational estimate from a published circumference method. It does not diagnose or assess any person, and health questions belong with a clinician.
Are measurements stored?
No. The calculation runs entirely in the browser. Circumferences and weight are never uploaded, stored or tracked.
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