What it calculates
Body fat percentage is the share of your body weight that is fat. It says more about fitness than weight alone.
This calculator uses the U.S. Navy circumference method, which needs only a tape measure.
How it works
Logarithms of your measurements and height are combined in published equations to estimate body density and then fat percentage.
Formula
Men: 495 ÷ (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450
- Women: 495 ÷ (1.29579 − 0.35004·log₁₀(waist + hip − neck) + 0.221·log₁₀(height)) − 450
- All measurements in centimetres
How to use it
- Measure neck, waist and (women) hips with a flexible tape, relaxed, not pulled tight.
- Enter measurements, height and weight.
- Read the estimate and range.
For the default measurements —
Why it helps
- Needs no special equipment.
- Useful for tracking change over time with consistent measuring.
Limitations
- Typical error is a few percentage points.
- Measurement technique affects the result.
- Ranges shown are fitness categories, not clinical thresholds.
Frequently asked questions
How accurate is it?
Reasonable for tracking trends; clinical methods such as DEXA are more accurate.
Do you store what I enter?
No. This calculator runs entirely in your browser. Your measurements and dates are not sent to or stored on our servers.
Sources
- Prediction of percent body fat for U.S. Navy men and women from body circumferences and height — Hodgdon JA, Beckett MB — Naval Health Research Center (1984) (checked 2026-09-27)
This calculator gives a general estimate only. It is not medical advice, a diagnosis or a treatment plan, and it does not replace a consultation with a doctor or registered dietitian. Your inputs stay in your browser and are not stored by UrbanFiling.