FFMI Calculator
Fat-Free Mass Index
Formula
FFMI = LBM(kg) / height(m)²
Normalized FFMI = FFMI + 6.1 × (1.8 - height)
FFMI Ranges
| 17-18 | Below average |
| 19-20 | Average |
| 21-22 | Above average |
| 23-25 | Excellent/Elite |
| 26+ | Suspicious (PEDs?) |
Related
Complete Guide to FFMI Calculator
Fat-Free Mass Index (FFMI) is like BMI for muscle. It measures how much lean mass you carry relative to your height, providing a way to assess muscular development independent of body fat.
Understanding FFMI
FFMI was developed to distinguish between people who are heavy due to muscle versus fat. A high BMI with low body fat = high FFMI = muscular. It's particularly useful for assessing natural muscular potential.
Natural Limits
Research on pre-steroid era athletes suggests FFMI of 25 is approximately the natural limit for most men. Values above 25 are rare without performance-enhancing drugs. Elite natural bodybuilders typically reach 24-25.
FFMI by Category
- Below 18: Underweight or untrained
- 18-20: Average male
- 20-22: Above average, regular lifter
- 22-25: Advanced, near genetic potential
- 25+: Elite or enhanced
Frequently Asked Questions
Fat-Free Mass Index measures lean mass relative to height. It's like BMI but accounts for muscle vs fat. FFMI = lean body mass in kg divided by height in meters squared.
For men: 18-20 is average, 20-22 above average, 22-25 excellent. Women typically have FFMI 2-3 points lower. FFMI above 25 for men is rare naturally.
Research suggests ~25 is the natural limit for most men. Pre-steroid era athletes and modern drug-tested competitors rarely exceed this. Genetics, training, and diet affect where you fall.
FFMI above 25-26 strongly suggests PED use, as it's extremely rare naturally. However, genetic outliers exist. FFMI should be one consideration, not definitive proof.
Normalized FFMI adjusts for height differences. Shorter people tend to have higher FFMI naturally. The adjustment makes comparisons between different heights fairer.
Build muscle through progressive resistance training while managing body fat. FFMI increases when you add muscle or lose fat (both increase lean mass relative to fat). It takes years to approach natural limits.
Yes, though women have different ranges (typically 14-21). Female FFMI norms are less studied, but the concept applies equally - it measures muscular development for height.