Body fat calculator
Estimate body fat from tape measurements.
About this calculator
You only need a tape measure. Measure in centimetres, and keep the tape level and snug without squeezing the skin.
Tape methods give an estimate, and results can vary with how you measure. Repeating the same method over time is more useful than any single reading.
How it works
Uses the US Navy circumference equations. Measure at the narrowest part of the neck and at the navel for the waist.
Worked example
- Sex: Female
- Height: 170 cm
- Neck: 34 cm
- Waist: 80 cm
- Hip: 98 cm
Estimated body fat: 29.1%
The story behind it
Where the idea came from: James Hodgdon and Mitchell Beckett, US Naval Health Research Center, 1984.
The US Navy needed a way to estimate body fat for large numbers of sailors without lab equipment. In 1984, Hodgdon and Beckett published equations that use only a tape measure and height. The method is still popular because it's cheap and repeatable, though it remains an estimate.
Why you can trust this calculator
- It runs in your browser. Nothing you type into it is sent anywhere.
- The method is explained on this page, so you can check it yourself.
- Free to use, with no sign-up.
- Results are estimates, not medical advice.
- Spotted a mistake? Tell us and we'll look into it.
After 15 years as a mathematics educator, I built CalculStore to give students, teachers, professionals and anyone working with numbers simple, reliable tools.
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