Body Fat Calculator
Estimate your body fat percentage using the US Navy circumference method. Enter your measurements below for an instant, private result — no signup required.
Your Measurements
Body Fat Calculator – Estimate Body Fat Percentage (US Navy Method)
A body fat calculator estimates the percentage of your body weight that is fat tissue. Unlike scale weight or BMI alone, body fat percentage better reflects body composition. This free tool on www.usacalc.online uses the widely used US Navy circumference method based on height, neck, waist, and (for women) hip measurements.
How the US Navy Body Fat Formula Works
The US Navy method uses logarithmic formulas derived from circumference measurements:
Men: %BF = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76
Women: %BF = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387
(Measurements in inches; metric inputs are converted automatically.)
Body Fat Categories (General Adult Ranges)
- Essential fat: Men 2–5%, Women 10–13%
- Athletes: Men 6–13%, Women 14–20%
- Fitness: Men 14–17%, Women 21–24%
- Average: Men 18–24%, Women 25–31%
- Obese: Men 25%+, Women 32%+
How to Measure Accurately
- Neck: Just below the larynx (Adam’s apple), tape slightly sloping downward
- Waist (men): At navel level; (women): at the narrowest point
- Hip (women): At the widest point of the buttocks
- Keep the tape snug but not compressing skin; measure at the same time of day
Body Fat vs BMI
BMI only uses height and weight. Two people with the same BMI can have very different body fat levels. A body fat calculator gives a clearer picture of composition, especially for athletic or muscular individuals.
Limitations
Circumference methods are estimates. Accuracy depends on measurement technique. Results are not a medical diagnosis. For clinical precision, DEXA, Bod Pod, or hydrostatic weighing are more accurate. Consult a healthcare professional for personalized advice.
Final Thoughts
Tracking body fat percentage over time is often more useful than scale weight alone. Use this free body fat calculator on www.usacalc.online as a consistent baseline, measure the same way each time, and combine results with how you feel and perform.