Body Fat
Estimate body-fat percentage, fat mass, and lean mass. Free online calculator with formulas and step-by-step solutions.
Key formula
U.S. Navy body fat equation
About this tool
Body-fat percentage gives a different lens than scale weight alone because it tries to separate fat mass from lean mass. This tool is helpful for context, but users should still understand that circumference-based methods are estimates rather than direct measurement.
How to use this calculator
- Enter realistic personal values and double-check the chosen unit system before calculating.
- Use the result as a planning estimate, not as a diagnosis or guaranteed outcome.
- Compare the output with your goal, context, and any relevant professional guidance.
- Review the steps to understand how the estimate was produced from your inputs.