Lean mass relative to height
FFMI Calculator
Estimate fat-free mass index using your height, weight, and body-fat estimate.
Fat-Free Mass Index
FFMI describes estimated fat-free mass relative to height. FitCalc does not assign authoritative athletic categories or infer drug use.
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How FFMI differs from BMI
BMI uses total weight. FFMI divides estimated fat-free mass in kilograms by height in metres squared, so body-fat-estimate error flows directly into the result.
About the often-repeated FFMI 25 claim
A 1995 study observed normalized values around 25 among its relatively small male athlete sample. That finding is not a universal natural limit and cannot establish whether an individual uses performance-enhancing drugs. FitCalc makes no such inference.
Why normalized FFMI is not shown
The original height adjustment was developed in a specific male-athlete context. V1 reports the transparent standard index without presenting that adjustment as universally necessary.