FFMI or the Fat Free Mass Index is an alternative to body mass index (BMI) which accounts for an individual’s muscle mass. Normally, the average male scores about 19 and it is hard to score above 25 on a normal body type without using steroids or other banned substances.

The concept of FFMI is very similar to BMI. Although, here instead of measuring the entire body mass of a person in relation to their height, it rather measures the amount of muscles (fat-free mass) relative to a person’s height.

This indicator also accounts for the amount of total lean muscle mass in the body. Research also suggests that it can predict how much muscle your body can potentially gain under a general circumstance.

It is a pretty useful indicator for people who are trying to lose weight or extra body fat, specifically those engaging in strength training to develop muscles and reduce body fat.

FFMI is especially handy for serious body building enthusiasts and gym goers. Commonly used terminology associated with this concept and its computation are:

  • Total Body Fat = Weight in Kg * (body fat % / 100)
  • Lean Weight = Weight in Kg * (1 – (body fat % / 100)
  • FFMI = (Lean Weight in Kg / 2.2)/ ((Feet * 12.0 + Inches) * 0.0254)2
  • Adjusted FFMI = FFMI + (6.3 * (1.8 – (Feet * 12.0 + Inches) * 0.0254))