Prime Progression
FFMI Calculator
Fat-Free Mass Index — the metric that matters for lifters. How muscular are you relative to your height?
FFMI measures muscle development relative to height. A normalized value above 25 is near the natural limit for most men. Values above 27 are rare without pharmaceutical assistance.
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Get Prime ProgressionFrequently asked questions about FFMI
What is FFMI?
Fat-Free Mass Index measures the amount of lean (non-fat) mass relative to your height. It was introduced as a more meaningful alternative to BMI for people who carry significant muscle mass.
What's a good FFMI score?
For men, an FFMI of 20 is average, 22-23 indicates a well-trained physique, and 25 is often cited as the approximate natural limit. For women, those values are roughly 3-4 points lower. Scores above 25-26 for men are rare without performance-enhancing drugs.
Is FFMI better than BMI?
For anyone who lifts weights regularly, yes. BMI treats all weight the same, so a muscular person can be classified as overweight or obese. FFMI separates fat from lean tissue, giving a much more useful picture of body composition.