Body Fat Calculator (US Navy Method)
Estimate body fat using the US Navy method from neck, waist, and hip measurements in inches or cm.
Returns fat %, fat mass, lean mass, and fitness category.
The U.S. Navy body fat method estimates body fat percentage using circumference measurements, eliminating the need for underwater weighing or DEXA scans. It is widely used by the U.S. military for fitness assessments and is reasonably accurate (±3–4% of laboratory methods).
Formulas:
Men: % Body Fat = 86.010 × log₁₀(Abdomen − Neck) − 70.041 × log₁₀(Height) + 36.76
Women: % Body Fat = 163.205 × log₁₀(Waist + Hip − Neck) − 97.684 × log₁₀(Height) − 78.387
All measurements in inches. Use log base 10.
What each measurement means:
- Neck — measured just below the larynx (Adam’s apple), perpendicular to the neck’s long axis.
- Abdomen (men) — measured at the navel level, horizontal, at the end of a normal exhale.
- Waist (women) — measured at the narrowest point of the torso, horizontal.
- Hip (women) — measured at the widest point of the buttocks, horizontal.
- Height — in inches, without shoes.
Body fat percentage reference ranges:
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletic | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Worked example (male): Height: 70 inches (5'10"). Neck: 15 inches. Abdomen: 36 inches.
% Body Fat = 86.010 × log₁₀(36 − 15) − 70.041 × log₁₀(70) + 36.76 = 86.010 × log₁₀(21) − 70.041 × 1.8451 + 36.76 = 86.010 × 1.3222 − 129.19 + 36.76 = 113.72 − 129.19 + 36.76 = 21.29% body fat — average fitness range.