Body Fat Calculator — US Navy Method
Estimate body fat percentage using the US Navy circumference method. Requires only a tape measure — no calipers or scale needed. Includes category classification and lean mass estimate.
Enter height in inches. 5'10" = 70 inches.
Measure at the navel for men, at the narrowest point for women.
Measure just below the larynx (Adam's apple).
Related calculators
Frequently asked questions
How accurate is the US Navy method?
Studies comparing the Navy circumference method to DEXA (gold standard) report a mean error of ±3–4 percentage points for adults with typical body composition. It's substantially better than BMI (which doesn't distinguish fat from muscle) and comparable to bioelectrical impedance scales. Outliers: it underestimates BF% in heavily muscled athletes (broad shoulders + narrow waist throw the formula off) and overestimates in older adults with central fat distribution.
What is essential body fat?
Essential fat is the minimum body fat required for normal physiological function: hormone production, vitamin storage, organ insulation, neurological function. Men: ~3-5%. Women: ~10-13% (higher because of reproductive biology — breast tissue, uterine support, and ovulation reserves). Going below essential fat causes hormonal disruption, immune suppression, and in women, amenorrhea. Bodybuilders cut to 4-6% briefly for competition but cannot maintain it healthily.
Body fat percentage vs. BMI — which is better?
Body fat % is the better measure of health risk. BMI uses only height and weight, so a muscular athlete (low fat, high muscle) can register the same BMI as someone with the same weight but mostly fat. Studies show BF% better predicts cardiovascular risk, metabolic syndrome, and mortality at the individual level. BMI remains useful for population studies because it's measurable everywhere without equipment.