Body Fat % Calculator
Estimate body fat percentage from a few tape-measure circumferences, using the U.S. Navy method.
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How to estimate your body fat percentage
- Choose your sex and whether you’ll measure in centimetres or inches.
- Measure and enter your height, neck and waist (and hips, for women).
- Read your estimated body fat percentage.
The formula
The U.S. Navy method (all measurements in centimetres, converted automatically if you enter inches) 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.
Questions about body fat
Where should I measure?
The waist at the navel, the neck just below the Adam’s apple, and for women the hips at their widest. Keep the tape level and snug but not tight, and measure at the same time of day each time.
How accurate is the US Navy method?
It usually lands within a few percent of lab methods for most people, which is good for tracking changes over time. DEXA scans are more accurate but cost money.
What is a healthy body fat percentage?
Guides vary, but roughly 10–20% for men and 18–28% for women is commonly given as healthy for adults, with athletes lower. Ask a health professional about what suits you.
Why use body fat instead of BMI?
Body fat separates fat from muscle, which BMI can’t, so it suits people who are very muscular or who are training.