How the Navy method works
The US Navy formula estimates body fat from simple circumference measurements. It correlates well with hydrostatic weighing for most people (±3%), but it's an estimate — hydration, recent exercise and measurement technique all shift the numbers.
- Men: BF% = 495 ÷ (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450
- Women: BF% = 495 ÷ (1.29579 − 0.35004·log₁₀(waist + hip − neck) + 0.22100·log₁₀(height)) − 450
Measure at the narrowest points: neck just below the larynx, waist at the navel (men) or narrowest point (women), hips at the widest. Take each twice and average.
All measurements in the formula above are in centimeters; imperial inputs are converted before calculation.
Reference categories
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Above average | 25%+ | 32%+ |
The Navy method loses accuracy above ~35% body fat and for very muscular individuals. For clinical decisions, use DEXA or professional skinfold measurements.