Body fat calculator.
Estimate your body fat percentage with the US Navy tape method, using a few simple measurements. The calculator also splits your weight into fat mass and lean mass.
Your measurements
LiveMeasure relaxed, in centimetres or inches. Hip is used for women only. Switch units any time.
Body fat
18.4%
Average
The tape method is an estimate within a few percent; calipers or a scan are more precise. Calculations run in your browser; nothing is stored.
How it works
A tape and a formula
The US Navy method estimates body fat from the circumference of your neck and waist, plus your hip for women, set against your height. It needs only a tape measure and is accurate to within a few percent for most people, which is why the military adopted it.
For a man 180 cm with a 40 cm neck and 90 cm waist, it estimates about 18.4 percent body fat. With your weight, the calculator then splits the total into fat mass and the lean mass underneath.
The full guide
The complete body fat guide.
How the tape method works, what the categories mean, and how to measure accurately.
Why body fat beats weight alone
The scale cannot tell muscle from fat, but body fat percentage can. Two people at the same weight and height can look and function very differently depending on how much of that weight is fat. Tracking body fat shows whether changes are coming from fat or muscle, which the scale alone hides.
The US Navy method
This calculator uses the US Navy circumference formula. It compares the difference between your waist and neck, plus hip for women, to your height, using logarithms to estimate the fat percentage. It is a tape-measure method, so there is no special equipment, but it does assume a typical body shape.
Body fat categories
For men, rough bands are: essential fat 2 to 5 percent, athletes 6 to 13, fitness 14 to 17, average 18 to 24, and above 25 in the obese range. Women carry more essential fat, so each band sits about ten points higher. The calculator shows which band your estimate falls in.
How to measure accurately
Use a flexible tape, keep it level and snug without compressing the skin, and measure relaxed after breathing out. Measure the neck below the larynx, the waist at the navel for men or the narrowest point for women, and the hip at the widest point. Taking each measurement twice and averaging improves accuracy.
Limits of the estimate
No tape method is exact. Body shape, where you store fat and measurement error all affect the result, so treat it as a useful estimate rather than a precise figure. For higher accuracy, calipers, a DEXA scan or bioelectrical impedance are options, though each has its own trade-offs.
The formula
Measure,
then estimate.
The US Navy formula turns a few circumferences and your height into a body fat estimate, no scales or scanners needed.
Try the BMI calculator ›# US Navy (men), cm
%BF = 495 / (1.0324 − 0.19077·log₁₀(waist−neck)
+ 0.15456·log₁₀(height)) − 450
# women add hip
use (waist + hip − neck)
# fat mass
fat mass = %BF × weightQuestions
Body fat questions.
How do I measure body fat at home?
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The US Navy method needs only a tape measure. Record your height, neck and waist, plus hip for women, and the calculator estimates your body fat percentage from those circumferences.
How accurate is the US Navy method?
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It is usually within about three to four percent of a more precise method like a DEXA scan, which is good for a tape measurement. Accuracy depends on measuring carefully and on having a typical body shape.
What is a healthy body fat percentage?
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For men, the fitness range is roughly 14 to 17 percent and average is 18 to 24; for women each band is about ten points higher. Some essential fat is necessary for health, so very low figures are not the goal.
What is the difference between fat mass and lean mass?
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Fat mass is the weight of body fat; lean mass is everything else, including muscle, bone, organs and water. The calculator splits your total weight into the two using your estimated body fat percentage.
Is this body fat calculator free and private?
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Yes. It is completely free with no sign-up, and every calculation runs locally in your browser, so nothing you enter is stored or sent anywhere.
About the developer
Jean Borg
Jean builds and maintains every calculator on freecalculators.pro from Malta. The body fat calculator uses the US Navy circumference method and is provided for general information, not medical advice.