MEDICINE · FREE TOOL
BMI-based body-fat estimator
Explore a population-level body-fat estimate derived from BMI, age and a study coefficient.
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How this calculation works
Deurenberg 1991 adult equation:BF%=1.20×BMI +0.23×age −10.8×sex −5.4; male 1/female 0 per original study. Reported standard error4.1 percentage points is not an individual confidence interval. Adults 20–83 only; measurement error and population differences can be substantial. Not for pregnancy, athletic assessment, diagnosis or treatment decisions.
Reference: method and limitations. Method reviewed October 22, 2026.
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Health calculations are educational estimates and do not replace a clinician’s assessment. Your inputs and individual circumstances can materially change how useful an estimate is.