Estimate body fat percentage from circumference measurements using the U.S. Navy method.
Developed for military fitness assessment, the Navy method estimates body fat from a few tape measurements — height, neck, and waist for men, plus hips for women — using logarithmic equations validated against underwater weighing. It won't match a DEXA scan exactly, but done carefully it's typically within 3–4 percentage points, free, and repeatable at home.
The calculator also converts your result into fat mass and lean mass in pounds, and places you in a fitness category:
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Acceptable | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Because the method tracks circumference, it's especially good at showing change over time — remeasure monthly and watch the trend rather than obsessing over any single reading. Pair it with the BMI calculator for two complementary views of the same question.
Studies generally find it within about 3–4 percentage points of laboratory methods for most people, with larger errors at the very lean and very high extremes. Its real strength is consistency — the trend across repeated measurements is more reliable than any single number.
The male and female equations were validated separately. Women's fat distribution differs, and adding the hip circumference substantially improves the estimate's accuracy for women — leave it blank only if you selected 'Male'.
Yes. Essential fat — roughly 2–5% for men and 10–13% for women — is required for hormone function, insulation, and organ protection. Sustained levels below that range are dangerous, not impressive.