Body Fat Calculator

Body fat percentage is a more meaningful measure of body composition than weight alone. It tells you how much of your total body mass is made up of fat versus lean tissue (muscle, bone, organs and water). The U.S. Navy circumference method, used by this calculator, has been shown to correlate well with more expensive measurement techniques such as DEXA scans and hydrostatic weighing.

The method uses simple tape-measure circumferences. For men, it requires neck and waist measurements. For women, it adds the hip circumference. These are then combined with height in a logarithmic formula that estimates the proportion of body fat.

Healthy body fat ranges differ between men and women because women naturally carry more essential fat for reproductive function. For men, an "athletic" range is roughly 6–14%; for women, 14–21%. Above 25% (men) or 32% (women) is generally classified as obese.

For accurate results, measure with a flexible non-stretch tape, in the morning, on bare skin and breathing normally. Wrap the tape snugly without compressing the skin. As with any single measurement method, use this as a rough estimate. Consult a healthcare provider for clinical body composition analysis.

Multiple measurement methods exist, each with trade-offs. Skinfold calipers measure subcutaneous fat at standardized sites and are inexpensive but require skill — measurement error can exceed 5% between operators. Bioelectrical impedance analysis (BIA), used in many home scales, passes a small current through the body and estimates composition based on resistance; it is convenient but sensitive to hydration, recent meals, and exercise. DEXA scans use X-ray technology and are the clinical gold standard, with error rates under 2%, but cost $50–$150 per scan.

Body fat percentage varies dramatically by age, sex, ethnicity, and training history. Essential fat — the minimum needed for biological function — is roughly 3–5% for men and 10–13% for women. Athletes typically sit at 6–14% (men) or 14–21% (women). Acceptable ranges for general health are 14–24% (men) and 21–31% (women). Above 25% (men) or 32% (women) is classified as obese. Women's higher essential fat percentage relates to reproductive function and is genetically protected even during aggressive dieting.

Body fat distribution matters as much as total percentage. Android (apple-shaped) fat distribution, with fat concentrated around the abdomen and visceral organs, carries higher cardiovascular and metabolic risk than gynoid (pear-shaped) distribution, where fat sits on hips and thighs. The U.S. Navy method indirectly captures this by including waist circumference, but a dedicated waist-to-hip ratio gives clearer information about distribution-related risk.

Changing body fat percentage takes time and consistency. Reducing body fat by 1% per month is a realistic and sustainable rate. Faster losses typically include significant muscle loss, which lowers metabolic rate and changes body shape unfavorably. Combine a moderate calorie deficit (300–500 calories below maintenance), 1.6–2.2 g of protein per kg of bodyweight, resistance training 3–4 times per week, and adequate sleep. Re-measure every 4–6 weeks rather than daily to see meaningful trends and avoid discouragement.