Free Lean Body Mass Calculator

Estimate your fat-free body mass using the Boer formula.

Lean body mass includes muscle, bone, organs, and water — everything except fat. It's often used to set protein intake targets (many recommendations are per kg of lean mass rather than total body weight) or to track body composition changes alongside weight.

Frequently Asked Questions

What's the difference between lean body mass and muscle mass?
Lean body mass includes muscle plus bone, organs, and body water — it's a broader category than muscle alone.