Body Fat %
Navy method body fat estimate
Navy method
About This Calculator
Body fat percentage measures the proportion of your total weight that is fat mass. The Navy method uses circumference measurements (neck, waist, hip) to estimate body fat without calipers or expensive equipment. While less accurate than DEXA scans, it provides a useful estimate for tracking trends over time.
Formula
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
All measurements in cm or inches (formula adjusts)
Example Calculation
Male, height 180 cm, neck 38 cm, waist 85 cm
- log₁₀(85−38) = log₁₀(47) = 1.6721
- log₁₀(180) = 2.2553
- %BF = 86.010×1.6721 − 70.041×2.2553 + 36.76
- = 143.8 − 157.9 + 36.76 = 22.7%
Estimated body fat: 22.7%
Body Fat % Categories (ACSM)
| Category | Men | Women |
|---|---|---|
| Essential fat | 2-5% | 10-13% |
| Athletes | 6-13% | 14-20% |
| Fitness | 14-17% | 21-24% |
| Acceptable | 18-24% | 25-31% |
| Obese | 25%+ | 32%+ |
Frequently Asked Questions
How accurate is the Navy body fat method?
The Navy method is accurate to within 3-4% compared to DEXA scan for average individuals. It becomes less accurate at extremes (very lean or very obese). It's best used to track changes over time rather than as an absolute measurement.
What is the most accurate way to measure body fat?
DEXA (Dual-Energy X-ray Absorptiometry) scan is the gold standard, accurate to 1-2%. Hydrostatic (underwater) weighing is also very accurate. BodPod uses air displacement. Skinfold calipers with a trained technician can reach 3-4% accuracy. Consumer devices (scales, handheld) are often 5%+ off.
Is body fat or BMI more useful?
Body fat percentage is more useful. BMI doesn't distinguish between fat and muscle — a muscular athlete can have an 'obese' BMI with excellent body composition. Body fat percentage directly measures what we care about, though it requires more measurement effort.
How quickly can I reduce body fat?
Sustainable body fat reduction is about 0.5-1% per month for most people. Faster reduction risks muscle loss. Track body fat alongside scale weight — sometimes the scale doesn't change but body fat decreases as fat is replaced by muscle.