How to Calculate Body Fat
What is Body Fat?
A body fat percentage calculator estimates fat mass as a proportion of total body weight using skinfold measurements, circumference methods (US Navy), or BMI-derived formulas.
Formula
US Navy (men): %BF = 86.010×log(waist−neck) − 70.041×log(height) + 36.76; (women): 163.205×log(waist+hip−neck) − 97.684×log(height) − 78.387
- %BF
- Body fat percentage (%)
- W
- Waist circumference (cm)
- H
- Height (cm)
- N
- Neck circumference (cm)
Step-by-Step Guide
- 1US Navy method (men): 86.010×log(waist−neck) − 70.041×log(height) + 36.76
- 2US Navy method (women): 163.205×log(waist+hip−neck) − 97.684×log(height) − 78.387
- 3Jackson-Pollock: uses skinfold caliper measurements
- 4DEXA scan is the gold standard but requires clinical equipment
Worked Examples
Input
Male, waist 85cm, neck 38cm, height 178cm
Result
Body fat ≈ 86.010×log(47) − 70.041×log(178) + 36.76 ≈ 17.5%
Frequently Asked Questions
What's a healthy body fat percentage?
Athletes: 6-13% (male), 14-20% (female). Fitness: 14-17% (male), 21-24% (female). Varies by age and sport.
Is BMI the same as body fat %?
No. BMI = weight/height² and doesn't distinguish muscle from fat. Body fat % is more accurate for health.
How accurate is the Navy method?
Accurate within ±2-3%. DEXA scan (clinical) is more precise but requires equipment and cost.