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Interactive calculator

Body-Fat %
Calculator

A tape measure and three numbers get you a solid body-fat estimate. This uses the U.S. Navy circumference method, then breaks your weight into fat mass and lean mass.

  • Free · no sign-up
  • Runs in your browser
  • Nothing stored

Your measurements

in
lb
Used for the fat / lean mass breakdown.
in
Just below the larynx, tape sloping slightly down in front.
in
At the navel (men) or the narrowest point (women).

Estimated body fat

— %

—

Fat mass—
Lean mass—

Category bands (ACE-style): Men — essential 2–5%, athletes 6–13%, fitness 14–17%, average 18–24%, obese 25%+. Women — essential 10–13%, athletes 14–20%, fitness 21–24%, average 25–31%, obese 32%+.

This calculator is for educational purposes only and is not medical advice, diagnosis, or treatment. Results are estimates based on published formulas and population averages — your individual values may differ. Nothing here is calculated on a server: everything runs in your browser and no data is stored or sent anywhere. Always consult a qualified clinician before making health, medication, or training decisions.