FFMI Calculator
Estimate your fat-free mass index from weight, height, and body fat percentage.
Quick answer: enter your details below and click Calculate FFMI — your result appears instantly, right here in your browser. Nothing you enter is uploaded or stored.
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How to use
- Enter your weight and height.
- Enter your estimated body fat percentage.
- Click Calculate FFMI.
About this tool
Fat-free mass index (FFMI) looks at lean mass relative to height, which makes it a useful companion to BMI for people who train. Enter your weight, height, and body fat estimate and the tool works out lean mass first, then FFMI. Because body fat estimates vary, treat the result as an estimate, not a precise lab value.
Frequently asked questions
How accurate is my body fat input?
Home estimates can be off by several percent, so treat FFMI as a ballpark figure.
Can FFMI be too high?
Very high values usually reflect heavy muscle mass, but the figure alone says nothing about health.