Body Composition
Fat-free mass index
Lean mass divided by height in metres squared. Removes most of the effect of stature so different-sized people can be compared.
The Formula
FFMI = LBM / height(m)^2
Lean mass divided by height in metres squared. Removes most of the effect of stature so different-sized people can be compared.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| LBM | Lean body mass | kilograms | Estimated lean mass in kilograms. |
| h | Height | metres | Height in metres, so centimetres divided by 100. |
| FFMI | Fat-free mass index | kilograms per square metre | Lean mass normalised for height. |
What Each Symbol Means
LBMkilograms
Lean body mass
Estimated lean mass in kilograms.
hmetres
Height
Height in metres, so centimetres divided by 100.
FFMIkilograms per square metre
Fat-free mass index
Lean mass normalised for height.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate lean body mass page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Lean Body Mass, filed under Health. Every number the guide produces comes from substituting into this one line.