How it works
Estimate your body-fat percentage and lean mass using the US Navy circumference method.
Enter your sex, height, weight, and neck and waist measurements (plus hip for women). The calculator applies the US Navy circumference equations to estimate body-fat percentage and splits your weight into fat mass and lean mass.
Formula
Men: BF% = 495 ÷ (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450. Women: BF% = 495 ÷ (1.29579 − 0.35004·log10(waist + hip − neck) + 0.22100·log10(height)) − 450.
waist- Waist circumference (cm)
neck- Neck circumference (cm)
hip- Hip circumference (women) (cm)
height- Height (cm)
Examples
- Male, 180 cm, 85 kg, 90 cm waist, 40 cm neckMale · height 180 · weight 85 · neck 40 · waist 90≈ 18.4% body fat · ≈ 15.6 kg fat mass · ≈ 69.4 kg lean mass
Frequently asked questions
How accurate is the US Navy method?
It is a screening estimate based on circumference measurements. Tape-measure accuracy and hydration affect results; it is not as precise as DEXA or hydrostatic weighing.
Why is hip required for women?
The female equation uses hip circumference because women typically carry more fat around the hips and thighs.
How to read the result
Body-fat percentage is one indicator of body composition. Fat mass and lean mass are derived from your total weight and the estimated percentage. This is not a medical diagnosis.
Limitations
Population-average estimate. Less reliable for athletes, older adults, and pregnant people. Results are clamped to a plausible 2–75% range to avoid absurd values from mis-measurement.
Source: US Navy circumference method (Hodgdon & Beckett, 1984); fat/lean mass derived from body-fat percentage.