Free tools
Body fat calculator.
Estimate body fat with a tape measure, using the US Navy circumference method.
How it works
The US Navy tape method.
Hodgdon and Beckett built these equations for the US Navy in 1984 by comparing tape measurements with underwater weighing. The US Department of Defense later adopted them for all its services. Measurements go in as inches; centimetres are converted first.
Men: % fat = 86.010 × log(waist − neck) − 70.041 × log(height) + 36.76
Women: % fat = 163.205 × log(waist + hips − neck) − 97.684 × log(height) − 78.387
log is base 10. Example: a man 180 cm tall with a 38 cm neck and 85 cm waist comes out at 16.2%.Limits
- Typical error is about 3.5 percentage points either way.
- It tends to read high on very lean people and low at higher body fat.
- It was built on US military personnel. Very muscular necks or unusual builds throw it off.
- For adults. Not for pregnancy.
Sources
- Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men from body circumferences and height. Naval Health Research Center Report 84-11, 1984. Women: Report 84-29, 1984.
- Hodgdon JA, Friedl K. Development of the DoD body composition estimation equations. Naval Health Research Center, San Diego, 1999.
- US Department of Defense. Instruction 1308.3, DoD Physical Fitness and Body Fat Programs Procedures, 2002.