FFMI Calculator
The fat-free mass index (FFMI) is your fat-free mass divided by your height squared: a way to see how much non-fat mass you carry for your height, and to follow it as you train. Enter your height, weight and body fat %. The math runs in your browser: nothing you type is sent anywhere.
Your estimated FFMI
Fill in the form and press Calculate to see your FFMI, your normalized FFMI, your fat-free mass and your fat mass.
- FFMI
- Normalized FFMI (adjusted to 1.8 m)
- Fat-free mass
- Fat mass
These are estimates, not medical or dietary advice. How we estimate, with sources
What FFMI tells you, and what it doesn't
FFMI is your weight minus your fat, divided by your height in meters squared, so it is in kg/m², like BMI. It counts everything that isn't fat, including bone, water and organs, not only muscle. And it is only as good as the body fat % you enter: an estimate from a tape-measure method, calipers or a body-composition scale can be several points off, and so the FFMI moves with it.
FFMI and normalized FFMI
Taller people tend to come out with a higher FFMI at the same build. The normalized FFMI from the same 1995 study adjusts the score to a height of 1.8 m: FFMI + 6.1 × (1.8 − your height in m). At 1.8 m the two are equal. For example, at 180 cm, 80 kg and 15% body fat, the fat-free mass is 68 kg and both come out at 21.0.
Typical FFMI for men and women
A study of more than 5,000 adults in Switzerland, measured by bioelectrical impedance, found these medians for ages 18 to 34. Half of the people measured were above and half below; it describes a population, not a target.
Median FFMI, ages 18 to 34 (Schutz et al. 2002)
| Group | Median FFMI (kg/m²) |
|---|---|
| Men | 18.9 |
| Women | 15.4 |
People who lift regularly often sit above these medians. Compare your FFMI with your own earlier scores, measured the same way, rather than with other people.
FFMI vs BMI
BMI divides your whole weight by your height squared, so it can't tell muscle from fat: a muscular lifter and a person with more fat can share the same BMI. FFMI takes the fat out first, which makes it a better fit for lifters, at the cost of needing a body fat estimate.
How to raise your FFMI
FFMI goes up as you add muscle: hard, progressive strength training, enough protein (1.6–2.2 g per kg of body weight a day in the meta-analysis on our sources page) and, for most lifters, a small calorie surplus. Expect it to move slowly, a few tenths a year once you are past your first years of training.
Use FFMI to track your progress
One score says little; the trend says more. Measure your body fat the same way each time, at the same time of day, every month or two, and watch whether your FFMI climbs while you bulk and holds while you cut. The BodyMacros app keeps your weight trend and your lifts in one place, so you can see both move.
FAQ
What is a good FFMI?
There is no single good score. In a large study of adults aged 18 to 34, the median FFMI was 18.9 kg/m² for men and 15.4 kg/m² for women, and people who lift often sit above that. A better question is whether your own FFMI is rising over the months you train, measured the same way each time.
What's the difference between FFMI and normalized FFMI?
FFMI is fat-free mass divided by height squared. Taller people tend to score higher at the same build, so the normalized FFMI adjusts the score to a height of 1.8 m by adding 6.1 × (1.8 − your height in meters). Above 1.8 m the normalized score is lower than the raw one; below it, higher.
Is FFMI better than BMI for lifters?
For lifters, usually yes. BMI uses your whole weight, so muscle pushes it up the same way fat does, and a muscular person can read as overweight. FFMI removes the fat first. Its weak spot is the body fat estimate it needs: an error of a few points there moves the FFMI too.
What is a normal fat-free mass range?
It depends on height, sex and age, which is why FFMI divides by height squared. In a study of more than 5,000 Swiss adults aged 18 to 34, the median FFMI was 18.9 kg/m² for men and 15.4 for women. Your own fat-free mass in kg is your weight minus your fat mass.
Track this in the app
Log your food and your lifts in one place. Your estimates adjust each week to how you eat and train.
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