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Body fat percentage calculator
Body fat percentage tells you how much of your weight is fat, something the scale and BMI alone do not reveal. This tool uses the US Navy method, the most popular one without lab equipment, which estimates fat from body circumferences and height. Measure with a tape and enter the values in centimeters.
Body fat reference categories
| Category | Men | Women |
|---|---|---|
| Essential | 2% to 5% | 10% to 13% |
| Athletic | 6% to 13% | 14% to 20% |
| Fitness | 14% to 17% | 21% to 24% |
| Acceptable / average | 18% to 24% | 25% to 31% |
| Above range | 25% or more | 32% or more |
How the US Navy method works
Men: %fat = 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450
Women: %fat = 495 / (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450
Measurements go in centimeters. For a man with a 90 cm waist, a 40 cm neck and a height of 180 cm, the formula returns about 18.4% fat. For a woman with an 80 cm waist, a 100 cm hip, a 34 cm neck and a height of 165 cm, the result is around 31.4%. The method was developed by Hodgdon and Beckett at the Naval Health Research Center in 1984 and is still used by the US Navy precisely because it needs nothing but a tape measure.
Margin of error and limits
By circumference, the typical error is on the order of 3 to 4 percentage points versus lab methods such as X ray densitometry (DEXA) or hydrostatic weighing, which are the reference. Accuracy depends heavily on measuring at the same spot every time, with the tape snug but not tight. Use the value to track your own progress over time, not to compare with another person to the decimal. Combine it with the BMI calculator and the ideal weight calculator for a fuller picture. Method source: Hodgdon and Beckett, Naval Health Research Center, 1984.
Disclaimer: an educational circumference estimate with a known margin of error. For a precise clinical measure, seek tests such as DEXA and the guidance of a health professional.
Last updated: · Methodology and sources