Body Fat Calculator — US Navy Method
Estimate body fat percentage with the US Navy method, plus fat mass and lean body mass.
Fill in your details, then check your personalized result and recommendations.
Formula
Men: 495 ÷ (1.0324 − 0.19077·log₁₀(waist−neck) + 0.15456·log₁₀(height)) − 450
Worked example
Man waist 90, neck 40, height 180 cm → ~18% body fat
What the body fat calculator does
This tool estimates the percentage of your body weight that is fat using the US Navy circumference method, a field-tested technique that needs only a tape measure. From your body-fat percentage it also derives your fat mass and lean body mass, which together describe your body composition far better than weight or BMI alone.
How the formula works
The Navy formula uses the circumference of your neck and waist (and hips for women) relative to your height. These measurements correlate with the amount of subcutaneous fat you carry. The logarithmic equation was validated against hydrostatic weighing and produces a reliable estimate when you measure consistently.
How to interpret your result
Body-fat ranges differ by sex. For men, essential fat is around 2–5%, athletes 6–13%, fitness 14–17%, average 18–24%, and above 25% is high. For women the bands are higher because of essential reproductive fat: essential 10–13%, athletes 14–20%, fitness 21–24%, average 25–31%, and above 32% high. Tracking the trend over weeks matters more than any single reading.
Health recommendations
To lower body fat, combine a moderate calorie deficit with resistance training to preserve lean mass, and keep protein high. Measure at the same time of day under the same conditions for consistency. Use the Lean Body Mass and TDEE calculators to plan a fat-loss phase that protects muscle.
FAQ
+How accurate is the US Navy method?
It is typically within 3–4% of more advanced methods like DEXA when measured carefully.
+Where do I measure my waist?
Men measure at the navel; women at the narrowest point. Keep the tape level and snug.
+What is a healthy body fat percentage?
Roughly 10–20% for men and 18–28% for women, varying with age and fitness.