Body Fat Calculator
Body fat percentage with the US Navy or BMI method
Quick answer
Body fat can be estimated without equipment from body circumferences (US Navy method: neck, waist, height, plus hip for women) or from BMI with the Deurenberg formula. These are estimates: less precise than skinfolds, DEXA or bioimpedance, but useful for tracking trends over time.
| Category | Men | Women |
|---|---|---|
| Essential | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Acceptable | 18–24% | 25–31% |
| Obesity | ≥ 25% | ≥ 32% |
The two methods
US Navy method (circumferences)
Developed by the US Navy (Hodgdon & Beckett, 1984), it estimates body density from circumferences and converts it to body fat with the Siri equation. It needs neck, waist and height (plus hip for women). It is surprisingly accurate when measurements are taken carefully.
Deurenberg formula (BMI)
Body fat (%) = 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4 (sex: male = 1, female = 0). It only needs weight, height, age and sex, but being BMI-based it does not separate muscle from fat and tends to overestimate in muscular people.
Which method to choose
The US Navy method is generally more reliable because it measures fat distribution directly; the Deurenberg method is handy when you cannot measure circumferences. For a fuller picture pair it with BMI, the waist-to-height / waist-to-hip ratios and ideal weight.
Disclaimer
Results are estimates for information only and do not replace a professional assessment (skinfolds, DEXA, bioimpedance) or the advice of a doctor or dietitian.
Related tools
Frequently asked questions
How do you calculate body fat without calipers?
Is the US Navy method accurate?
Why can the BMI method overestimate fat?
Sources
- Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center, 1984 (Reports 84-11, 84-29).
- Deurenberg P, Weststrate JA, Seidell JC. Body mass index as a measure of body fatness: age- and sex-specific prediction formulas. Br J Nutr. 1991;65(2):105-114.