Body Fat Calculator
Body fat percentage is the proportion of your total body mass that is fat tissue. Unlike BMI, body fat percentage distinguishes between fat and lean mass (muscle, bone, water), making it a more accurate indicator of fitness and health risk.
Tip: Waist circumference alone is a strong predictor of cardiovascular risk. Men with waist >40 in (102 cm) and women >35 in (88 cm) have significantly elevated risk.
- 1Measure height, neck circumference, and waist circumference in inches
- 2For women, also measure hip circumference
- 3Apply the US Navy formula: Men: 86.010×log(waist−neck) − 70.041×log(height) + 36.76
- 4Women: 163.205×log(waist+hip−neck) − 97.684×log(height) − 78.387
- 5Compare result to age and sex-specific body fat categories
US Navy vs DEXA
The US Navy method is a convenient field estimate (±3–4% error). For clinical accuracy, DEXA (dual-energy X-ray absorptiometry) or hydrostatic weighing are the gold standards.
Essential fat
Essential fat is the minimum needed for normal physiological function. It is ~3–5% for men and ~10–13% for women. Going below these levels is dangerous.
| Category | Men | Women |
|---|---|---|
| Essential Fat | 2–5% | 10–13% |
| Athletic | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Fun Fact
Elite marathon runners typically have 5–11% body fat (men) or 10–18% (women). However, very low body fat impairs hormone function and immune response.