Estimate your body-fat percentage with the US Navy method using body circumferences, plus fat mass and lean mass.
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Measure with a tape: neck, waist (and hip for women). The result appears instantly.
The US Navy method uses body circumferences. The margin of error is a few percent versus lab methods.
Body fat ≈ 16.9% · FitnessInformational estimates, not medical advice. We use standard formulas (WHO, Mifflin-St Jeor, US Navy method). Instant in-browser calculation, no account, no data sent. For medical decisions, consult a professional.
The US Navy method estimates body fat from circumferences and height. For men neck and waist are used; for women the hip is added:
A man with a 85 cm waist, 38 cm neck and 175 cm height has ≈ 18% body fat — the “fitness” category.
It is the share of your total weight made up of fat tissue. Unlike BMI, it distinguishes fat from muscle, giving a more accurate picture of body composition.
It uses body circumferences and height. For men, neck and waist are measured; for women the hip is added too. The formula applies logarithms to these measurements.
As a guide: for men 14–18% is “fitness” and 18–25% average; for women 21–25% is “fitness” and 25–32% average. Below these you enter the athletic range, above them toward excess.
With a tape held horizontally and flush to the skin without squeezing. Measure the neck below the larynx, the waist at navel level and the hip at its widest point.
It has a margin of about 3–4% versus reference methods such as DEXA. Still, it is free, fast and useful for tracking change over time.
Fat mass is the weight of fat tissue; lean mass (or fat-free mass) includes muscle, bone, organs and water. Their sum is total body weight.
Women naturally carry a higher share of essential fat needed for hormonal and reproductive function. That is why the healthy thresholds are higher for women.
For athletes and muscular people, body-fat percentage is more meaningful, because BMI can misclassify muscle as excess weight. Ideally view them together.
Through a moderate calorie deficit, enough protein and strength training to preserve muscle. Fat loss is slower and healthier than extreme diets.