By ToolzHive
About this tool
The body fat calculator estimates what share of your weight is fat, using the U.S. Navy circumference method: measurements of your neck, waist and (for women) hips, together with your height. It also shows a BMI-based estimate for comparison, splits your weight into fat mass and lean mass, and places your result in the American Council on Exercise categories from essential fat to obese.
How to use Body Fat Calculator
- Choose your units and sex, then enter your age, height and weight.
- Measure your neck just below the larynx, your waist at the navel and, for women, your hips at the widest point. Keep the tape level and snug but not tight.
- Read your body fat percentage, category and the fat versus lean mass breakdown.
Worked example
A man who is 175 cm tall with a 38 cm neck and an 85 cm waist has about 17% body fat by the Navy method, in the "fitness" range. Measuring again every few weeks under the same conditions shows whether fat is really going down.
How accurate is the U.S. Navy method?
It is usually within about 3–4 percentage points of lab methods like DEXA scans for most people. Accuracy depends on careful, consistent measuring, so take each measurement two or three times.
What is a healthy body fat percentage?
For adults, the American Council on Exercise lists about 14–24% as fitness to average for men and 21–31% for women. Essential fat, the minimum needed for health, is about 2–5% for men and 10–13% for women.
Why measure body fat instead of BMI?
BMI cannot tell muscle from fat, so muscular people can be labelled overweight. Body fat percentage describes your body composition more directly.
Put this guide into practice
- Body Fat Calculator — Estimate your body fat percentage with the U.S. Navy tape measure method.