Body composition
Body Fat % Calculator
Estimate body fat percentage from a few tape-measure readings, using the U.S. Navy circumference method.
Body composition
Estimate body fat percentage from a few tape-measure readings, using the U.S. Navy circumference method.
Estimate only — accuracy depends on careful, consistent measuring.
Neck: just below the larynx, tape sloped slightly down at the front.
Waist: at the narrowest point (men) or the navel (women).
Hip (women): at the widest point of the hips.
Keep the tape snug but not compressing skin, and measure at the same time of day for consistency.
Developed for military fitness assessments, this method estimates body fat percentage from a small set of circumference measurements — neck, waist, and (for women) hip — rather than requiring specialized equipment like calipers or a DEXA scan.
The method uses logarithms of your waist, neck, and height measurements. For men, it's based on the difference between waist and neck; for women, the sum of waist and hip minus neck. It's not something you'd want to compute by hand often — that's what the calculator above is for.
The Navy method is generally within a few percentage points of more precise lab methods for most people, which makes it a practical option for tracking changes over time. It tends to be less precise for people at the extremes of the height or body-composition range.
| Category | Men | Women |
|---|---|---|
| Very lean | Under 6% | Under 14% |
| Athletic | 6–13% | 14–20% |
| Fit | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Above average | 25%+ | 32%+ |
No single field method is as precise as a lab DEXA scan, but the Navy method is a reasonably reliable and repeatable estimate for tracking trends over time.
Height helps normalize the circumference measurements, since two people with the same waist size but different heights typically carry body fat differently.
Double-check that your waist measurement is genuinely larger than your neck measurement (for men) — this is the most common input error, and an invalid combination won't produce a usable result.