What is lean body mass?

Lean body mass (LBM), also called fat-free mass, is everything in your body that is not fat — muscle, bone, organs and water. It is useful for setting protein targets and drug dosing.

Which formula does this use?

The Boer formula, a well-validated equation that estimates LBM from weight, height and sex. It is a population estimate, not a direct measurement like a DEXA scan.

No. The Boer formula runs entirely in your browser and none of your inputs are sent to a server or stored.

Lean Body Mass Calculator

Lean mass and fat mass from the Boer formula.

Lean body mass calculator — Boer formula

Your lean body mass (LBM) is everything except fat — muscle, bone, organs and water. This calculator uses the Boer formula to estimate your lean mass, fat mass and approximate body-fat percentage from your height, weight and sex.

Enter your details in metric or imperial and the breakdown appears instantly — all computed in your browser, nothing uploaded.