Body Fat Percentage Calculator
Estimate your body fat percentage using the U.S. Navy circumference method based on height, waist, neck, and (for women) hip measurements.
Formula
U.S. Navy Circumference Method
Male:
BF% = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
Female:
BF% = 163.205 × log₁₀(waist + hips − neck) − 97.684 × log₁₀(height) − 78.387
All measurements in inches. Metric inputs are converted before calculation.
Fat Mass = Body Weight × (BF% / 100)
Lean Mass = Body Weight − Fat Mass
BMI = Weight (kg) / Height² (m²)
Assumptions & References
- Based on the U.S. Navy Body Fat Formula developed by Hodgdon & Beckett (1984), used by the U.S. military for fitness assessments.
- Waist is measured at the navel for men and at the narrowest point for women; neck just below the larynx.
- Body fat categories follow American Council on Exercise (ACE) guidelines: Essential Fat, Athletes, Fitness, Average, Obese.
- This method has a margin of error of approximately ±3–4% compared to DEXA scans.
- Not suitable for children under 10, pregnant women, or highly muscular individuals (may underestimate fat).
- BMI is provided for reference only and does not distinguish fat from muscle mass.
- Reference: Hodgdon, J.A. & Beckett, M.B. (1984). Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center.