Fat-Free Mass Calculator (Boer Formula)
Estimate adult fat-free mass and fat-free mass index with the Boer equations.
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Estimated fat-free mass
—
Boer anthropometric estimate; not a direct measurement
Fat-free mass index
—
Estimated FFM divided by height squared
About
This calculator estimates adult fat-free mass with the sex-specific Boer equations based on weight and height. Fat-free mass index (FFMI) scales that estimate to height squared. Both are modeled estimates and are distinct from measurements obtained by DXA, bioelectrical impedance, air displacement, or isotope dilution.
Formula
Interpretation
Input units: Weight may be entered in kg or lb and height in cm or inches. Inputs are converted to kilograms and centimeters before the Boer equation is applied.
Worked example: For a 70 kg, 175 cm male, estimated FFM = 0.407 × 70 + 0.267 × 175 − 19.2 = 56.0 kg; FFMI is about 18.3 kg/m².
Applicable population: The Boer equations are adult anthropometric estimates. They should not be generalized automatically to children, pregnancy, substantial edema, amputations, or body shapes far outside the derivation setting.
Limitations: Prediction error may be important for an individual. Estimated FFM and FFMI are not DXA, BIA, or another direct body-composition result and are not assigned a diagnostic category here.
FAQ
Disclaimer
Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.