FFMI Calculator
Your Fat-Free Mass Index answers a question body weight and BMI cannot: how much muscle you carry for your height. Two people can weigh the same and look nothing alike. FFMI is the number that tells them apart.
Enter your height, weight and body fat percentage and you get your FFMI, the height-normalized version researchers use to compare athletes, and the band it falls in. It is an estimate, not a medical measurement, and it is only as accurate as your body fat figure. Do not have one? Start with the Body Fat Calculator.
Feminine
Masculine
Your height-normalized FFMI
Above average: Clearly trained. A year or two of consistent lifting lands here.
Normalized to a 1.80 m frame (Kouri et al., 1995)
FFMI 20.9
Lean mass over height squared, before the height correction
149.6 lb lean mass
Your weight minus its fat
26.4 lb fat mass
At 15% body fat
- Below average Under 18Less lean mass than most men your height carry.
- Average 18 to 20Around the median for a young adult man (18.9).
- Above average 20 to 22Clearly trained. A year or two of consistent lifting lands here.
- Advanced 22 to 25Years of serious training. Most lifters never pass this band.
- At the ceiling 25+The upper edge found in drug-free athletes. Rare, and worth a second look at the inputs.
FFMI moves about a quarter point for every point of body fat for an 80 kg, 1.80 m person, so the body fat you enter matters as much as the weight. For women the upper bands are an extrapolation: no study has set a drug-free ceiling for them.
- Not sure of your body fat? The Body Fat Calculator estimates it from a tape measure.
- See what your lean mass is worth in protein and resting calories with the Lean Body Mass Calculator.
- Turn it into a calorie target with the TDEE Calculator.
FFMI is only as accurate as the body fat you feed it, and a few points either way moves the band. A body scan reads one to three photos of your physique and returns body fat with a range, your FFMI and a per-region breakdown. Your first scan is free with an account.
Get your body scanFFMI: lean mass over height squared
Take your weight, remove the fat, and divide what is left (in kilograms) by your height in meters, squared. It is BMI with the fat taken out, so it asks how much lean tissue you carry for your size [2].
Normalized FFMI: tall and short on one scale
Lean mass does not scale with height exactly as the formula assumes, so taller people read higher. Kouri's correction adds 6.1 points for every meter you are below 1.80 m (and removes them above it) so everyone is compared as a 1.80 m frame [1]. The headline number on this page is the normalized one.
The middle of the scale is 18.9 and 15.4
In a large Swiss sample of healthy adults, the median FFMI of 18 to 34 year olds was 18.9 for men and 15.4 for women [2]. That is the Average band. It is where untrained people sit, not a target.
Below average or average
Plenty of room, and the quickest gains. Lift three or four days a week, progress the weights, and eat enough protein. Work out what to eat with the TDEE Calculator.
Above average or advanced
You are past the beginner curve, so progress is slower and rewards precise training and a small calorie surplus. See what your lean mass means for protein and resting burn in the Lean Body Mass Calculator.
At the ceiling
Check your inputs first. A body fat reading a few points too low is the usual reason. If it holds up, you are in rare territory and the gains left are small.
It is only as good as your body fat
FFMI is lean mass, and lean mass is weight times (1 minus body fat). A 4 point error in body fat moves a typical man's FFMI by about one full point, enough to change band. Use a method you trust, or the Navy estimate in the Body Fat Calculator with its 3 to 4 point error in mind.
25 is a landmark, not a law
Kouri found 25 to be about the upper edge among 74 athletes who had not used steroids, while steroid users went past it [1]. That is a small sample from the mid-1990s, so treat a result at or above 25 as a prompt to recheck your inputs, and be skeptical of any single threshold.
Women have no study of their own
The upper bands for women keep the men's spacing above the female median of 15.4. They are a reasonable yardstick, not a measured limit. FFMI also says nothing about where your muscle is, or how strong it is.
Water and glycogen move it
Lean mass includes water. Creatine, a carb-loaded day or heavy sodium can shift scale weight and the lean number with it. Compare readings taken in similar conditions.