Body Fat Calculator
Estimate your body-fat percentage and fitness category
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Body-fat percentage is the share of your body weight that is fat. It is a better health and fitness indicator than weight or BMI alone. The U.S. Navy circumference method is accurate within ~3–4% when measurements are taken correctly; the BMI method is a rough estimate when you have no tape measure.
How to use this body fat calculator
Pick one of two methods: the U.S. Navy tape-measure method (default) or a quick BMI-based estimate. For the Navy method, select your sex and enter your height, waist and neck circumferences — women also add the hip measurement. For the BMI method you only need age, height and weight. You can switch between metric (cm·kg) and imperial (in·lbs) units at any time, and the result appears instantly with no sign-up.
How to read your result
Your result is a body-fat percentage with a category badge: essential fat, athletes, fitness, average or high. For men, roughly 6–13% is athletic, 14–17% fit, 18–24% average and 25%+ high; for women the bands sit higher — 14–20% athletic, 21–24% fit, 25–31% average, 32%+ high — because women naturally carry more essential fat. As with any body metric, the trend over weeks matters more than a single reading, so measure under the same conditions each time.
The formula and the science behind it
The default calculation is the U.S. Navy circumference method, developed at the Naval Health Research Center by Hodgdon and Beckett in 1984. It estimates body density from logarithms of your waist, neck (and hip) girths plus height, and typically lands within about 3–4% of laboratory methods such as underwater weighing. The alternative BMI method uses the Deurenberg equation (1.2 × BMI + 0.23 × age − 10.8 × sex − 5.4), a population-level estimate for when you have no tape measure.
Limits and practical tips
Tape technique matters: measure on bare skin, keep the tape level and snug but not tight, and always measure at the same time of day. Circumference formulas can misread very muscular or very lean physiques, and the BMI-based estimate is only a rough average. For a fuller picture, pair this tool with our BMI, TDEE and macro calculators, project changes with the weight simulator — and log your meals in the CaloNote app to turn numbers into progress.
Frequently Asked Questions
- What is a healthy body-fat percentage?
- Roughly 10–20% for men and 18–28% for women is considered fit-to-healthy. Essential fat is about 3–5% (men) and 10–13% (women).
- Is the Navy method or BMI method more accurate?
- The U.S. Navy tape method is more accurate (±3–4%) when measured correctly. The BMI method is a rough estimate when you have no tape measure.
- How do I reduce body fat?
- Maintain a moderate calorie deficit, eat enough protein, and combine strength training with cardio to lose fat while preserving muscle.