How it's calculated
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
waist, neck, hip, height = body measurements in inches (cm ÷ 2.54). BF% = body-fat percentage. US Navy (Hodgdon–Beckett) circumference method; women add the hip measure. Fat mass = weight × BF% ÷ 100.
Reference ranges
| ACE category | Men | Women |
|---|---|---|
| Essential fat | 2-5% | 10-13% |
| Athletes | 6-13% | 14-20% |
| Fitness | 14-17% | 21-24% |
| Average | 18-24% | 25-31% |
| Obese | 25%+ | 32%+ |
Common questions
How accurate is the Navy method?
It usually lands within 3 to 4 percentage points of a DEXA scan, which is good for a tape-only method, though loose measurements throw it off.
Why do women add a hip measurement?
The female formula includes hip circumference because women carry more lower-body fat, and adding it improves the estimate.