What is the Fat-Free Mass Index?
Fat-Free Mass Index “FFMI” is an index that accounts for a person’s muscle relative to their weight and height. It is similar to the “Body Mass Index” when it comes to function.
BUT, Fat-Free Mass Index focuses specifically on the muscle-fat ratio.
Fat-Free Mass Index requires 3 inputs to calculate your muscle mass: Your height, your weight and your body fat percentage.
To calculate your body fat percentage check our “Body Fat Calculator”.
Mathematical Formulas to Calculate FFMI
Total Body Fat = Weight in Kg x (body fat % / 100)
Lean Weight = Weight in Kg x (1 - (body fat % / 100)
FFMI = (Lean Weight in Kg / 2.2)/ ((Feet x 12.0 + Inches) x 0.0254)2
Adjusted FFMI = FFMI + ( 6.3 x (1.8 - (Feet x 12.0 + Inches) x 0.0254))
FFMI Ranges for Men
| Description | FFMI Range | Body fat percent |
|---|---|---|
| Skinny guy | 17-18 | 10-18 |
| Typical average guy | 18-20 | 20-27 |
| Fat guy | 19-21 | 25-40 |
| Athlete / regular gym user | 20-21 | 10-18 |
| Advanced gym freak | 22-23 | 6-12 |
| Elite strength athlete (bodybuilders, etc.) | 24-25 | 8-20 |
FFMI Ranges for Women
| Description | FFMI Range | Body fat percent |
|---|---|---|
| Skinny woman | 14-15 | 20-25 |
| Typical average woman | 14-17 | 22-35 |
| Fat woman | 15-18 | 30-45 |
| Athlete / regular gym user | 16-17 | 18-25 |
| Advanced gym freak | 18-20 | 15-22 |
| Elite strength athlete (bodybuilders, etc.) | 19-22 | 15-30 |
Why should you use the FFMI Calculator?
Fat-Free Mass Index is very helpful to everybody involved in the fitness industry. Involving in weight-training and strength-training requires you to build muscle, but also to lose fat.
FFMI helps you to understand how is your body recomposition journey going, where you stand and where you should be. Competitive bodybuilders use it to know whether they need to add more muscle, or they are good in relation to their height.
FFMI Ranges
Skinny guy/woman: This means that you need to put on some muscles. Weight-training is your best option.
Typical Average guy/woman: This means that you need to do body recomposition. Basically, to lose fat and build muscle at the same time.
Fat guy/woman: This means that you need to lose some fat, then build muscle after.
Athlete, Advanced Gym Freak, and Elite Strength athlete: You don’t need to do anything, just maintain!
