About the Body Fat Calculator
Body fat percentage from the US Navy tape method, with fat mass, lean mass and your fitness category.
Also known as: body fat percentage, navy body fat, bf% calculator, fat percentage calculator.
How to use this calculator
- Enter units, sex, neck circumference (cm), waist circumference (cm) and the other fields.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
US Navy method using log of waist, neck (and hip) circumferences and height
Worked example
Using the values pre-filled in the calculator above:
- Units: Metric (kg, cm)
- Weight = 80 kg
- Height = 178 cm
- Sex: Male
- Neck circumference (cm) = 38
- Waist circumference (cm) = 90
the calculator returns:
- Body fat: 20.1%
- Category: Average
- Fat mass: 16.1 kg
- Lean mass: 63.9 kg