Health
Body fat percentage calculator (US Navy method)
Estimate body fat % from a few tape-measure readings: waist, neck, height (and hip for women). The US Navy formula is fast, free, and within ±3-4% of DEXA scan results for most adults.
Formula
Body fat percentage is a more meaningful metric than BMI because it directly measures composition rather than just mass/height. The US Navy circumference method, developed in the 1980s, lets you estimate it with a measuring tape — no caliper, no scale, no scan needed.
The formula uses waist, neck, and height for men, with hip added for women (women carry proportionally more lower-body fat). Accuracy is good for typical body shapes: ±3-4% vs DEXA. It's less accurate for athletes (overestimates fat in muscular people with thick necks) and very lean or very obese populations.
Measurements matter: tape should be snug but not compressing skin. Waist at navel, neck just below larynx, hip at widest part. Stand relaxed, breathe normally. Measure twice and use the average. All values in centimeters.
Examples
- 01Man, 178 cm tall, 85 cm waist, 38 cm neck→ ≈ 15.2% — Fitness category
- 02Woman, 165 cm tall, 75 cm waist, 32 cm neck, 95 cm hip→ ≈ 24.5% — Fitness category
- 03Man, 175 cm tall, 100 cm waist, 40 cm neck→ ≈ 28.7% — Obese category
FAQ
- Within ±3-4% for typical body types. Most accurate in the 10-30% range. Tends to overestimate for muscular athletes (thick necks reduce the waist-neck differential) and underestimate at extremes. Caliper methods (Jackson-Pollock 3-site) are similarly accurate when done by an experienced person.