Body Fat Calculator

The U.S. Navy Body Fat Method

The U.S. Navy method estimates body fat percentage using simple circumference measurements — neck, waist, and (for women) hip — combined with height, using a formula derived from hydrostatic weighing research. It was developed for military fitness assessment because it requires no special equipment beyond a tape measure, unlike DEXA scans, hydrostatic weighing, or bioelectrical impedance devices. While not as precise as lab methods, it's been validated as reasonably accurate for the general population, typically within 3-4% of more sophisticated methods.

How to Measure Correctly

Neck: measure just below the larynx (Adam's apple), tape sloping slightly downward to the front. Waist: for men, measure at the navel; for women, measure at the narrowest point, usually between the ribs and hips. Hip (women only): measure at the widest point around the buttocks. Keep the tape snug but not compressing the skin, and measure at the same time of day for consistency if tracking over time.

Body Fat Percentage Categories

For men: essential fat is 2–5%, athletes typically 6–13%, fitness 14–17%, average 18–24%, obese 25%+. For women: essential fat is 10–13%, athletes 14–20%, fitness 21–24%, average 25–31%, obese 32%+. Women naturally carry more essential fat due to reproductive and hormonal function, which is why the healthy ranges differ significantly between sexes.

Frequently Asked Questions

How accurate is the Navy method compared to DEXA scanning?

Research suggests the Navy method typically comes within 3-4 percentage points of DEXA scan results for most people, though accuracy can decrease for very lean or very high body fat individuals. It's best used as a convenient tracking tool rather than a clinically precise measurement.

Why does the formula differ between men and women?

Men and women store fat differently — men tend toward abdominal (visceral) fat while women tend toward hip and thigh (subcutaneous) fat — so the formula includes hip measurement for women to account for this different distribution pattern.

How often should I remeasure?

Monthly is usually sufficient to track meaningful change — body composition doesn't shift dramatically week to week, and daily fluctuations from water retention can be misleading if measured too frequently.