Calculator Tools
Body Fat Calculator
Calculate body fat percentage with the U.S. Navy tape-measure method. Get your category, lean mass, and fat mass in metric or imperial, no signup.
Unit system
Centimeters for circumferences and height, kilograms for weight.
Biological sex
Uses neck and waist circumference plus height.
Common samples
Range: 1 to 635 kg.
Range: 100 to 272 cm.
Below the larynx, with the tape level.
At the navel, after a normal exhale.
Used only for the BMI-method comparison estimate.
Body fat categories (American Council on Exercise)
2 - 5%
Essential fat
The minimum needed for normal physiological function. Going below this for long is unsafe.
6 - 13%
Athletes
Typical of competitive athletes, bodybuilders, and physique-focused training.
14 - 17%
Fitness
A lean, fit look with visible muscle definition. Common goal range for active adults.
18 - 24%
Average
Typical adult body fat range in the general population without a regular training routine.
25% or higher
Obese
Above the obese threshold for body fat. A lower body fat target is often advised by health professionals.
Categories follow the American Council on Exercise body fat ranges for adults. Toggle the biological sex above to see the matching range. This is a screening guide, not a target prescription.
How to measure for the Navy method
Tape and posture
Use a flexible cloth or fiberglass tape. Stand relaxed with arms at your sides. Keep the tape snug against the skin without compressing it. Take each measurement twice and use the average.
Neck
Measure just below the larynx (Adam's apple). The tape should be horizontal and slope slightly down at the front to avoid the larynx. Keep the head facing straight ahead.
Waist (men: at the navel)
Measure at the level of the navel after a normal exhale. Do not suck in or push out. Keep the tape level all the way around.
Waist (women: smallest point)
Measure at the smallest part of the natural waist, usually above the navel. Tape level, breathing normal.
Hip (women only)
Measure at the widest part of the hips and buttocks. Stand with your feet together. Keep the tape level and parallel to the floor.
Important
The U.S. Navy method is a tape-measure body fat estimate, not a medical diagnosis. It is most accurate for adults of average build, and it can over-estimate body fat in heavily muscled lifters or under-estimate it in untrained adults. For a precise measurement, consider DEXA, BodPod, or hydrostatic weighing. Always speak to a qualified medical professional for personal health advice.
How to use
- Pick a unit system (Metric or Imperial) and your biological sex. Female calculations also use hip circumference.
- Enter your weight, height, neck, and waist (and hip if female). Optionally add your age to enable the BMI-method comparison estimate.
- Read your body fat percentage, category, lean body mass, and fat mass in the Result panel. Use any Copy button to grab a value.
- Use Switch units to convert your numbers between metric and imperial, or click a sample profile to seed realistic measurements.
About this tool
Body Fat Calculator estimates your body fat percentage from simple tape-measure circumferences using the U.S. Navy method (Hodgdon and Beckett, 1984), the same formula used by the U.S. Department of Defense for body composition screening. Enter your weight, height, neck, and waist (and hip, for women) in metric (cm and kg) or imperial (in and lb), and the calculator returns your body fat percent to one decimal place, your category from the American Council on Exercise classification (essential fat, athletes, fitness, average, obese), your lean body mass (everything that is not fat: muscle, organs, bone, water) in both unit systems, and your fat mass in both unit systems. A second comparison estimate uses the Deurenberg 1991 BMI-method formula (BMI, age, and sex) so you can sanity-check the Navy result against a totally different model. A unit toggle preserves your typed numbers when you switch between metric and imperial, four sample profiles seed realistic male and female inputs in one click, and a measurement guide explains exactly where to place the tape for each circumference. Useful for tracking a fat-loss phase, sizing a recomposition target, comparing your current body fat to standard ranges, picking a body fat goal before macro planning, or just answering the "what is my body fat percentage" question without weighing in at a clinic. The Navy method is a screening estimate, not a medical or laboratory measurement. It is most accurate for adults of average build and can over-estimate body fat in heavily muscled lifters or under-estimate it in untrained adults. For a precise measurement consider DEXA, BodPod, or hydrostatic weighing, and always speak to a qualified medical professional for personal health advice. All math runs entirely in your browser, so the measurements you type never leave your device.
Free to use. Works in your browser. No signup, no login.
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