FFMI Calculator
Calculate your Fat-Free Mass Index (FFMI) and normalized FFMI from your weight, height, and body fat percentage. A muscularity score that BMI cannot give.
Calculator by Toolsloft ↗- FFMI
- 20.99
- Normalized FFMI
- 20.99
- Fat-free mass
- 68 kg
FFMI tells you how muscular you are for your height, using your lean mass instead of total weight. Lifters use it to track progress and to gauge how much natural muscle they have left to gain, since scores in the low twenties are near the drug-free ceiling for most people.
How this is calculated
Fat-free mass is weight x (1 - body fat percentage). FFMI is fat-free mass in kilograms divided by height in meters squared. Normalized FFMI adjusts to a 1.8 m reference height by adding 6.1 x (1.8 - height in meters), the standard correction from the Kouri et al. research on lean mass in athletes. Results depend on an accurate body fat reading.
How to use
- Enter your weight in kilograms and your height in centimeters.
- Enter your body fat percentage (use a body fat calculator if you do not know it).
- Read your fat-free mass, FFMI, and normalized FFMI.
Examples
- 80 kg, 180 cm, 15% body fat:
Fat-free mass 68 kg, FFMI 20.99, normalized 20.99 - 60 kg, 165 cm, 25% body fat:
Fat-free mass 45 kg, FFMI 16.53, normalized 17.44
FAQ
- What is a good FFMI?
- For men, roughly 18-20 is average, 20-22 is fit, and 22-25 is very muscular. A normalized FFMI around 25 is often cited as the natural limit, though genetics move that line.
- Why normalize FFMI?
- Taller people tend to score lower on raw FFMI at the same relative muscularity. Normalizing to a 1.8 m height lets you compare people of different heights fairly.
- Do I need my body fat percentage?
- Yes. FFMI is built on fat-free mass, so the result is only as accurate as your body fat estimate. A navy tape or caliper measurement is fine for tracking trends.