FFMI Calculator
Calculate your Fat-Free Mass Index to assess your natural muscle-building potential.
Body Composition
Weight
0 kg
Height
0 cm
Your FFMI Score
NaN
Elite/Enhanced
Generally exceeds natural limits
Lean Body Mass
0 kg
Fat Mass
0 kg
FFMI Scale Reference
< 19Below Average (Untrained)
19 - 21Average (Untrained)
22 - 24Above Average (Well-Trained Natural)
25 - 26Exceptional (Near Natural Limit)
> 26Elite/Enhanced (Exceeds Natural Limits)
Improves TDEE accuracy if known
Scientific Basis
FFMI Formula: Kouri et al. (1995)
FFMI = (Lean Body Mass / Height²) + 6.1 × (1.8 - Height)
FFMI adjusts muscle mass for height, providing a better indicator than raw weight. The formula includes a height correction factor to account for frame size.
Natural Limits:
Research suggests FFMI of 25 is generally the upper limit for natural (non-enhanced) athletes. Scores above 26 are extremely rare without pharmaceutical assistance. However, individual genetics vary, and this is a guideline, not an absolute rule.
Accuracy Note:
FFMI accuracy depends on accurate body fat percentage measurement. Use DEXA, BodPod, or hydrostatic weighing for most accurate results. Calipers and bioimpedance can vary.