Body Fat % Calculator (US Navy Method)
The US Navy method estimates body fat percentage from circumference measurements — no calipers or scale tricks required. It's a regression equation derived from a study of US Navy personnel and tracks DEXA results within ~3-4% for most adults. Accurate enough for tracking trends; not a clinical measurement. Enter height, neck, waist (and hip for women) in metric or imperial and the tool returns body fat %, lean mass, fat mass, and a fitness category.
Body fat
16.9%
Fitness
Fat mass
12.7 kg
Lean mass
62.3 kg
US Navy circumference formula. Estimate only — DEXA scan is the gold standard. Track trends, not single measurements.
How to use
- Pick sex and units.
- Measure neck (below the larynx, snug), waist (at the navel for men; narrowest point for women), and hip (widest point — women only).
- Enter measurements and read the body fat %, lean mass, and fat mass.
Frequently asked questions
- How accurate is this vs DEXA?
- Studies show ~3-4% standard error for most adults. Less accurate for very lean athletes (underestimates) and very obese individuals (overestimates). Good enough to track progress over time.
- Why do women need a hip measurement?
- The female formula uses waist + hip - neck because women carry more fat below the waist. The male formula uses only waist - neck because men's fat distribution is more torso-centric.
- Where exactly do I measure?
- Neck: just below the larynx. Waist (men): at the navel. Waist (women): at the narrowest point. Hip (women): at the widest point including the buttocks. All measurements snug but not compressing skin.
- What's a healthy body fat %?
- Roughly: men 10-20%, women 18-28% for general fitness. Athletes are typically lower (6-13% men, 14-20% women). Below 4% (men) / 12% (women) is dangerous.
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