Body Fat Calculator — US Navy Method
CalculatorA body fat calculator estimates body fat percentage from tape-measured neck, waist (plus hip for women) circumferences and height using the US Navy circumference method.
What is it
The US Navy method is a body fat estimation formula developed by the Naval Health Research Center in 1984. It uses waist minus neck for men, and waist plus hip minus neck for women, together with height in a logarithmic equation. It only needs a tape measure, but typical error is around ±3 percentage points, so this tool also shows the BMI-based Deurenberg estimate for comparison. Both are statistical estimates and do not replace precise measurement such as DEXA or medical judgment.
How to use
- 1Enter the sex code (male 1, female 0), age, height, and weight.
- 2Enter neck and waist circumference in cm. Women also enter hip circumference; men enter 0.
- 3Press calculate to see the US Navy body fat percentage, the BMI-method estimate, and the category.
Reference
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Sources & standards
- Prediction of percent body fat for U.S. Navy men from body circumferences and height (Hodgdon & Beckett, 1984) - Naval Health Research Center
- Body mass index as a measure of body fatness: age- and sex-specific prediction formulas (Deurenberg, 1991) - British Journal of Nutrition
- Percent body fat norms for men and women - American Council on Exercise
FAQ
What is the body fat of a man with 175 cm height, 38 cm neck, and 85 cm waist?
About 16.9% by the US Navy method, in the fitness range. It is computed as 495 ÷ (1.0324 − 0.19077×log10(47) + 0.15456×log10(175)) − 450.
How do I take the measurements?
Measure the neck just below the larynx, the waist at navel level (men) or the narrowest point (women), and the hips at the widest point, keeping the tape level and snug but not compressing the skin.
Can this result diagnose obesity?
No. Both the circumference and BMI methods are estimates with roughly ±3 percentage point error. For diagnosis or treatment, use precise measurement such as DEXA and consult a medical professional.
Are my measurements sent to a server?
No. This calculator runs entirely in your browser and does not send or store your inputs.