Body fat calculator
You can estimate your body-fat percentage with a tape measure using the US Navy method, which the US Navy adopted because it needs no special kit. It uses your height, neck and waist, plus hip measurement for women. It is an estimate, not a scan, so a few percentage points either way is normal: use it to track change over time rather than as an exact figure. A DEXA scan is the gold standard. This is general information, not a medical measurement.
How this is worked out
This uses the US Navy circumference method, the body-fat estimate the US Navy adopted in the 1980s because it needs only a tape measure. All measurements are in centimetres:
men: 495 ÷ (1.0324 − 0.19077 x log10(waist − neck) + 0.15456 x log10(height)) − 450
women: 495 ÷ (1.29579 − 0.35004 x log10(waist + hip − neck) + 0.22100 x log10(height)) − 450
It is an estimate, not a scan. Tape methods can be a few points out either way, so use it to track change over time rather than as an exact figure. A DEXA scan is the gold standard.
Informational only, not a medical measurement. Editorially reviewed by FitCalcs, with each figure citing its source.
Calculators and Data Desk, FitCalcs
FitCalcs' editorial desk builds and documents the calculators, citing the underlying equation and the UK dataset behind every number. Health-related tools are editorially reviewed, with figures cited to named UK sources.
Last reviewed: 12 June 2026