Body Fat Calculator

Body fat percentage is a more meaningful health metric than weight or BMI alone. Two people can weigh the same and have the same BMI but have drastically different body compositions — one might be 18% body fat, the other 32%. This calculator estimates your body fat percentage without calipers, a DEXA scan, or gym equipment. It uses the US Navy circumference method, developed by Hodgdon and Beckett and validated across large military populations. The method requires only a tape measure: waist circumference, neck circumference, and — for women — hip circumference. These three measurements feed into a logarithmic formula that estimates fat distribution with reasonable accuracy for most adults. Results are shown alongside your lean body mass and fat mass in pounds or kilograms, and categorized against the American Council on Exercise ranges: essential fat, athletic, fitness, average, and obese. These categories are sex-specific because women carry more essential fat for hormonal and reproductive functions — a body fat percentage that would be "athletic" for a man is "essential fat" territory for a woman. The US Navy method is less precise than DEXA scanning or hydrostatic weighing, but it's within 3–4% for most people and far more accessible. Use it as a baseline and track trends over time rather than treating a single measurement as definitive.