Body Fat Calculator
Estimate body fat percentage from height, neck, waist and hip measurements, using the US Navy method.
- Category
- Acceptable
This calculator provides estimates only. It is general information, not medical advice or a diagnosis, and doesn't account for your full personal health circumstances. Speak with a doctor or qualified health professional before making health decisions.
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How this calculator works
This uses the US Navy circumference method — a published formula developed for military fitness screening, using just height and a few tape-measure circumference readings rather than specialised equipment (like calipers or a DEXA scan).
Measure your neck (just below the larynx), waist (at the navel), and — for the female formula — hips (at the widest point), in centimetres, along with your height. The formula differs by sex: men's uses waist and neck; women's also includes hip measurement, since fat distribution patterns differ between sexes.
This is a population-level estimate with a typical error margin of around ±3-4% body fat compared to more precise methods like DEXA scanning — useful for tracking your own trend over time, less useful as a single precise number.
Frequently asked questions
- How accurate is the Navy method?
- It's reasonably accurate for a tape-measure method — typically within about 3-4 percentage points of more precise methods like DEXA scanning — but it's still an estimate. Measurement technique (tape tension, exact landmark) affects accuracy more than with clinical methods.
- Why does the female formula need a hip measurement but the male one doesn't?
- The formula was calibrated separately for each sex against typical fat distribution patterns — women typically carry more fat around the hips, so that measurement improves the estimate for the female formula specifically.
- Is this the same as what a doctor or gym would measure?
- It's an estimate, not a clinical measurement. Gyms sometimes use skinfold calipers or bioelectrical impedance scales, and clinics may use DEXA scans — each method has its own margin of error, and results between methods won't match exactly.