How to Measure Body Fat Percentage
This calculator uses the US Navy Body Fat Formula — one of the most practical methods for estimating body fat at home. It was developed by Hodgdon and Beckett at the Naval Health Research Center and is used by the US military for fitness standards.
Men's formula: Body Fat % = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
Women's formula: Body Fat % = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
All measurements are at their narrowest/widest points: waist at the narrowest point (above the navel for men, at the navel for women), neck just below the larynx, hips at the widest point (women only). The formula has a margin of error of ±3–4% compared to DEXA scans.
Body Fat Percentage Categories (ACE)
- Essential fat: Men 2–5%, Women 10–13% — minimum for physiological function
- Athletes: Men 6–13%, Women 14–20% — lean, performance-oriented
- Fitness: Men 14–17%, Women 21–24% — above average fitness
- Average: Men 18–24%, Women 25–31% — acceptable health range
- Obese: Men 25%+, Women 32%+ — increased health risk
Frequently Asked Questions
What is a healthy body fat percentage?+
For men, 14–17% is fitness level and 18–24% is average/acceptable. For women, 21–24% is fitness level and 25–31% is average. Below essential fat levels (men <5%, women <13%) carries serious health risks. Athletes typically sit at 6–13% (men) and 14–20% (women).
How accurate is the Navy formula?+
The US Navy formula has a margin of error of approximately ±3–4% compared to DEXA scans (considered the gold standard). It is significantly more accurate than BMI for estimating body composition. For best results, measure three times and average, always at the same time of day.
How do I measure correctly?+
Measure waist at the narrowest point (for men: just above the navel; for women: at the navel). Measure neck just below the larynx (Adam's apple), keeping the tape snug but not tight. Women measure hips at the widest point. Take all measurements in centimeters or all in inches — do not mix units.
What is better than BMI for body composition?+
Body fat percentage methods — Navy formula, skinfold calipers, bioelectrical impedance — are all more informative than BMI because they distinguish fat mass from lean mass. DEXA scan is the gold standard. Hydrostatic weighing and Bod Pod (air displacement plethysmography) are also highly accurate.