Body Fat % Calculator
Estimate body fat percentage from a few tape-measure circumferences, using the U.S. Navy method.
Last updated
Educational tool, not medical advice. This circumference-based method is a population estimate, not a body composition scan — it can be off by several percentage points for a given individual. See our terms for details.
—Estimated body fat
The formula
The U.S. Navy method (all measurements in inches, converted automatically if you enter metric) is: for men, 495 ÷ (1.0324 − 0.19077×log₁₀(waist−neck) + 0.15456×log₁₀(height)) − 450; for women, 495 ÷ (1.29579 − 0.35004×log₁₀(waist+hip−neck) + 0.22100×log₁₀(height)) − 450. Measure the waist at the navel, the neck just below the larynx, and hips (for women) at the widest point — the closer and more consistent your tape measurements, the more useful the estimate.
Nothing entered here is sent to a server — the entire calculation runs as JavaScript in your browser tab.