Lean Body Mass Calculator
Everything that isn't fat: muscle, bone, organs and water.
Enter your values
Results update instantly as you type — no submit needed.
Results
- Lean body mass
- 130 lb
- Fat mass
- 40 lb
- Body fat
- 23.5%
- Fat-free mass index
- 19.2
Quick answer
Lean body mass is total weight minus fat mass; the Boer formula estimates it from height and weight alone.
Male LBM = 0.407·kg + 0.267·cm − 19.2
How to use the Lean Body Mass Calculator
- 1Choose your units.
- 2Enter weight, height and sex.
- 3Read lean mass and estimated fat mass.
Frequently asked questions
Why track lean mass?
During a diet it shows whether you are losing fat or muscle, which weight alone cannot tell you.
What is a good FFMI?
Around 19–21 for trained men and 15–17 for trained women; above 25 without drugs is very rare.