Body fat calculator
Estimate your body fat percentage with the U.S. Navy method from body measurements, then see your fat mass and lean body mass.
Profile and measurements
Enter measurements taken with a tape measure. The main calculation uses the U.S. Navy circumference method.
Measure just below the larynx without tightening the tape.
Measure horizontally at the narrowest point of the waist without pulling your stomach in.
For the female formula: measure around the widest part of the buttocks, keeping the tape horizontal.
Your estimated body composition
Compare with the BMI-based estimate
Both methods are statistical estimates. The difference illustrates the uncertainty of a calculation without a clinical body-composition measurement.
How to take the measurements
- Neck: just below the larynx, shoulders relaxed, without compressing the skin.
- Waist (female): at the narrowest point, with the tape parallel to the floor.
- Hips (female): around the widest part of the buttocks, with the tape parallel to the floor.
Method & sources
The main result uses U.S. Navy circumference equations: height, neck and abdominal circumference for men; height, neck, waist and hips for women. Weight is then used to convert the estimated percentage into fat mass and lean body mass. A second estimate based on BMI, age and sex uses the adult Deurenberg equation for comparison only.
U.S. Navy (measurements converted to inches) — Men: BF% = 86.010 × log₁₀(abdomen − neck) − 70.041 × log₁₀(height) + 36.76 · Women: BF% = 163.205 × log₁₀(waist + hips − neck) − 97.684 × log₁₀(height) − 78.387 · Adult Deurenberg: BF% = 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4 (sex = 1 male, 0 female)Limitations
- The U.S. Navy method estimates body composition from circumferences; it does not replace a clinical measurement such as DEXA.
- A few centimetres of difference when measuring the neck, waist or hips can change the result; always measure in the same way.
- The BMI-based estimate does not directly distinguish muscle from fat and may be less suitable for very muscular builds or extreme situations.