About Body Fat Calculator
Calculate body fat with clear inputs, instant results and a step-by-step explanation. This tool helps you compare values and check everyday estimates without creating an account.
How to use this tool
- Enter height (cm), waist circumference (cm), neck circumference (cm), hip circumference (cm; female formula), sex used by the equation, age (years, adult 20+).
- Check the units and select Calculate.
- Read your result alongside the formula and assumptions below. Use Reset to begin again.
Formula & method
Worked example
The prefilled numeric inputs provide a starting example. Calculate to see the output, then replace them with your own values.
What to keep in mind
For adult education only; not a diagnosis, treatment, or personalised target. Not suitable for pregnancy, children, or clinical fluid/diet planning. Discuss concerns with a qualified clinician. Use abdomen at the navel for men; natural waist and widest hip circumference for women. Measure the neck below the larynx without compressing the skin. This historical equation is not an official service assessment.
Sources & scope
CDC: adult BMI and screening limitations; Mifflin et al., resting energy expenditure equation. These support the BMI and resting-energy tools respectively; activity multipliers and water factors are estimates rather than personalised prescriptions. The body-fat tool uses the historical US Navy circumference equation; it is not an official military assessment. See Navy body-composition guidance for assessment context. Measurement technique and population affect accuracy.
Frequently asked questions
How precise is the result?
Display precision varies by tool; very large integer tools preserve exact integer results. Exact conversion factors can be precise, but estimates depend on the accuracy of your inputs and the assumptions listed above.
Are my calculator inputs saved?
No. Calculations run locally in this browser. Reloading the page clears your inputs.
Can I use this result for an important decision?
Use it as a reference and verify the applicable units, local standards, provider terms or professional requirements before acting.