Calculadora FFMI (Fat-Free Mass Index)

The FFMI (Fat-Free Mass Index) Calculator estimates the index of lean body mass relative to height, a key metric for muscle development. Unlike BMI, which uses total weight, FFMI focuses only on fat-free mass (muscles, bones, organs), making it popular among athletes and bodybuilders to assess genetic potential and hypertrophy levels.

The calculation is straightforward: divide lean body mass (in kg) by the square of height (in meters). For example, someone with 70 kg of lean mass and 1.75 m height has FFMI = 70 / (1.75²) ≈ 22.9. For heights other than 1.80 m, an adjustment is applied: add 6.1 × (1.8 − height). This standardizes the index for fairer comparisons across different statures.

Use this calculator to monitor gym progress, check if muscle gains are within natural limits (men: up to ~25; women: up to ~22), or identify possible steroid use (values above 25 for men). It is also useful for nutritionists and personal trainers to adjust diets and training. Remember that lean mass must be obtained via methods like bioimpedance or skinfold measurements.

Caveats: FFMI accuracy depends on the quality of lean mass measurement. Common errors include using home bioimpedance scales (which may overestimate) or neglecting the height adjustment. Also, FFMI does not distinguish muscle from other lean tissues (e.g., organs). For very tall or short individuals, reference values may not be fully accurate.