Lean Body Mass Calculator

Lean body mass splits a scale reading into the part that is fat and the part that is not, which is often the more useful half.

WeightIn kilograms. Divide pounds by 2.20462 first.HeightIn centimetres. Multiply inches by 2.54 first.SexThe formula uses different coefficients for each.

Lean body mass in kilograms

56.015

Fat mass in kilograms: 13.985
Body fat percentage: 19.98%
Fat-free mass index: 18.2906

Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.

The formula this calculator uses

LBM = 0.407W + 0.267H - 19.2 (men)

W: Body weight in kilograms
H: Height in centimetres
LBM: Lean body mass, everything that is not fat
FFMI: Fat-free mass index, lean mass divided by height squared

How to check the result by hand

1
Record weight in kilograms and height in centimetres
The coefficients are tied to those units. A weight in pounds or a height in inches has to be converted first, or the answer will be meaningless.
2
Apply the coefficient for your sex
Men use 0.407 times weight plus 0.267 times height minus 19.2. Women use 0.252 times weight plus 0.473 times height minus 48.3. The constants differ as well as the coefficients, so the two cannot be mixed.
3
Subtract to get fat mass
Take the lean mass away from total weight. For a 70 kilogram man with a lean mass of 56.015 kilograms, the fat mass is 13.985 kilograms.
4
Divide by weight for body fat percentage
13.985 divided by 70 is 0.1997857142857143, so about 19.98 percent of body weight is fat. This is an estimate from a height-weight formula, not a measurement.
5
Normalise by height for FFMI
Divide lean mass by height in metres squared. For 56.015 kilograms at 1.75 metres that is 56.015 divided by 3.0625, which is 18.29061224489796.

For worked examples, common mistakes and the limits of this formula, read the full How To Calculate Lean Body Mass page.