How to Calculate Body Fat Percentage (Navy Method Explained)
Step-by-step guide to the U.S. Navy body fat formula, how to measure neck, waist, and hip correctly, and why it beats BMI for estimating body composition.
The U.S. Navy method estimates body fat percentage from a tape measure and a formula — no scale, calipers, or scan required. It was developed as a fast field-test alternative to underwater weighing and remains one of the most accessible reasonably accurate methods available.
What you need to measure
- Neck: just below the larynx (Adam's apple), tape angled slightly downward at the front.
- Waist: at the narrowest point, usually level with the navel — for men, this is measured at the navel regardless of where the waist narrows.
- Hip (women only): at the widest point around the buttocks.
Keep the tape snug against the skin without compressing it, stand relaxed rather than sucking in your stomach, and measure at the same time of day each time for consistent results.
The 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.
All measurements go in centimeters.
Why it beats BMI
BMI only uses height and weight, so it can't tell the difference between a pound of muscle and a pound of fat. Because the Navy method is built from actual circumference measurements, it reflects where your weight is really carried — which is why a muscular person with a low waist measurement scores a much lower body fat percentage on the Navy method than on a BMI-based estimate, despite an identical BMI.
The Body Fat Calculator runs this formula for you instantly, in metric or imperial units, alongside your fat mass, lean mass, and category.