Estimate your body fat percentage with the U.S. Navy method or BMI. Calculate body fat mass and lean body mass using simple body measurements.
Estimate body fat percentage from tape measurements with the U.S. Navy equation, or use a simpler adult BMI-based estimate. Weight is optional for the Navy method.
Estimated body fat
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U.S. Navy method
Body fat mass–
Lean body mass–
Body weight–
Lean mass includes muscle, organs, bone, water and other non-fat tissues; it is not muscle mass alone.
The original Navy equations use different male and female calibrations. Choose the equation that best fits your physiology; neither can describe everyone accurately.
These are statistical estimates for general adult use, not diagnoses. Tape measurements do not directly measure fat. Results vary with body shape, age and population. These methods are not suitable substitutes for individual assessment during pregnancy or for children. Very low body fat is not inherently healthier.
What is body fat percentage?
Body fat percentage estimates what share of total body weight is fat tissue. It describes a different aspect of body composition than body weight alone. A tape-measure calculation is an estimate, not a direct measurement.
How do the two methods work?
The U.S. Navy method combines height with neck and waist measurements; the female equation also uses hip circumference. It was calibrated with sex-specific data and can differ from a direct body-composition assessment. The BMI method uses age, sex, height and weight to estimate body fat statistically. It is intended for adults and is less individualized.
How to measure neck, waist and hips
Stand straight without shoes. Keep the tape horizontal and snug, without compressing the skin. Measure the neck just below the larynx. For the male Navy equation, measure waist near the navel; for the female equation, use the narrowest waist point. Measure hips at the widest point. Do not hold the stomach inward, and use the same technique each time.
Body fat percentage vs BMI
BMI relates weight to height; it cannot separate fat from lean tissue. The Navy equation uses body circumferences to estimate composition. The two methods may disagree because they use different assumptions. For a weight-based comparison, see the Ideal Weight Calculator.
What is lean body mass?
Lean body mass is body weight minus estimated fat mass. It includes muscle, organs, bones, blood and water. If you enter your weight, this calculator shows both estimated masses. You can use the percentage as an optional input in the BMR Calculator; its Katch-McArdle formula uses fat-free mass.
How accurate are these estimates?
Circumference equations and BMI are statistical estimates. Their accuracy varies by body shape, age and population; small tape-placement changes can change the result. DXA scans, bioelectrical impedance and skinfold testing use different measurement techniques and can give different values. No single result is a diagnosis or a personal target.
Using body fat results responsibly
Compare repeated measurements only when taken consistently. Avoid interpreting a small change as a true change in body fat. During pregnancy, for children, or when health conditions affect body composition, seek an individualized assessment. For related energy and nutrition estimates, see the Calorie Calculator, TDEE Calculator and Macro Calculator.
Health & Fitness
Body Fat Calculator FAQ
How can I calculate my body fat percentage at home?
Use a tape to measure height, neck and waist, plus hips for the female Navy equation. Enter those values above. The result is an estimate, not a direct measurement.
How accurate is the U.S. Navy body fat calculator?
It is a population-based estimate. Accuracy depends on body shape and careful, consistent tape placement; an individual result may differ from a clinical measurement.
Can I calculate body fat without calipers?
Yes. The Navy method uses a tape measure; the BMI-based option needs only age, sex, height and weight.
What is the difference between BMI and body fat percentage?
BMI is weight divided by height squared. Body fat percentage estimates the portion of weight that is fat tissue.
How do I measure my waist for the Navy method?
Use navel level for the male equation and the narrowest waist point for the female equation. Keep the tape level and do not pull the stomach inward.
What is lean body mass?
It is total weight minus estimated fat mass, including muscle, organs, bone and water.
Do I need my weight for the Navy method?
No. Weight is optional for the body fat percentage. Enter it only if you also want fat mass and lean mass.
Why do body fat calculators give different results?
They use different inputs, population equations and measurement methods. Tape placement and normal biological variation also affect results.
