How to estimate lean body mass
Use a body-fat estimate and compare it with a height-based formula.
1
Enter weight and body fat
Use the same body-fat method each time for a consistent trend.
2
Add height and sex
These drive the Boer cross-check.
3
Compare the estimates
A small gap is expected; a large one suggests checking the body-fat measurement.
What does this tool do?
Lean body mass is everything that is not fat: muscle, bone, organs and water. This calculator derives it from weight and body-fat percentage, and compares the result with the height-based Boer equation.
The Formula
Lean mass = weight × (1 − body fat % ÷ 100); Boer: men 0.407W + 0.267H − 19.2, women 0.252W + 0.473H − 48.3Frequently Asked Questions
Is lean body mass the same as muscle?
No. Lean mass includes muscle, bone, organs and body water. Muscle is only one part of it.
Why do the two estimates differ?
The body-fat method relies on the measurement you enter, while the Boer equation uses height and sex. A measured DEXA scan is more precise than either.