FFMI Calculator
Calculate your Fat-Free Mass Index (FFMI): how much muscle you carry for your height, with a natural-lifter rating scale.
About this tool
FFMI is the metric the fitness community uses to measure muscularity independent of height and fat: lean mass divided by height squared, with a rating scale from average to near-natural-limit.
It answers the question BMI cannot: how much muscle are you actually carrying? Track it every 8-12 weeks alongside body fat — improving lean mass at a stable FFMI means real progress.
FAQ
What is FFMI?
Fat-Free Mass Index: lean body mass in kg divided by height in meters squared. It measures how much muscle you carry independent of fat.
What is a good FFMI?
18-20 average, 20-22 above average, 22-23.5 excellent, 23.5-25 near the natural ceiling for most men. Values above 25 are rare without enhancement.
How accurate is it?
FFMI accuracy depends entirely on body-fat measurement. Use the same method over time — the trend matters more than the absolute number.