This calculator estimates body fat percentage from body circumferences using the U.S. Navy method. The male equation uses height, waist, and neck; the female equation also uses hip circumference.
The method is practical when laboratory testing is unavailable, but measurement technique matters. Use a flexible tape, keep it level, and repeat measurements under similar conditions when tracking change.
Select the equation corresponding to the measurement protocol you intend to use.
Use standing height in centimeters.
Keep the tape level and avoid compressing the skin.
Use a consistent anatomical point and relaxed posture.
The female equation requires a hip measurement at the widest point.
Weight enables estimated fat mass and lean mass outputs.
Male: BF% = 495 ÷ (1.0324 − 0.19077 log10(waist − neck) + 0.15456 log10(height)) − 450
Female: BF% = 495 ÷ (1.29579 − 0.35004 log10(waist + hip − neck) + 0.22100 log10(height)) − 450
All circumferences use the same unit; this page uses centimeters.
The result is a circumference-based estimate of the percentage of total body weight represented by fat mass.
This method is not a diagnosis and may be less representative for some body shapes, athletes, or measurement conditions.
Given: Male equation, height 175 cm, waist 85 cm, neck 38 cm, body weight 75 kg.
Calculation: waist − neck = 47 cm. Applying the equation gives about 18.4% body fat. Fat mass = 75 × 0.184 = 13.8 kg. Lean mass = 75 − 13.8 = 61.2 kg.
Result: Approximately 18.4% body fat.
Use the location required by the protocol you follow and use the same location each time. Consistency is essential for trend comparisons.
The selected Navy equation includes hip circumference as an additional predictor. Leaving it out would change the model.
The logarithmic equation works when every circumference uses the same unit, but this page is configured and labeled for centimeters.
Circumference, skinfold, bioimpedance, and imaging methods use different assumptions. Hydration, device settings, and body shape can also affect results.
The male equation requires a positive waist-minus-neck value. The calculator will stop rather than apply a logarithm to an invalid measurement.