💪 FFMI Calculator (Fat-Free Mass Index)
Calculate your Fat-Free Mass Index (FFMI), a measurement of muscularity relative to height that is often used to track lean mass progress.
What FFMI measures
Fat-Free Mass Index (FFMI) measures how much muscle mass you carry relative to your height, similar to how BMI relates total weight to height. It is popular among strength trainees because it accounts for body fat, giving a clearer picture of muscularity than BMI or weight alone.
How this calculator works
Enter your height, weight, and estimated body fat percentage. The calculator subtracts your fat mass from your total weight to get fat-free mass, then divides that by your height in meters squared to get FFMI. It also shows a ‘normalized FFMI’, which adjusts the score to what it would be at a reference height of 1.8 meters, making it easier to compare between people of different heights.
For untrained men, typical FFMI is roughly 18 to 20; very muscular, drug-free men often reach the mid-20s. Ranges are generally a few points lower for women. Results depend heavily on the accuracy of your body fat percentage estimate. This tool is for general educational and planning purposes only.