Lean Body Mass Calculator
Estimate your lean body mass — everything in your body except fat — using the widely used Boer formula.
Why lean body mass matters
Lean body mass includes muscle, bone, organs, and water — essentially everything that isn't fat tissue. It's a useful figure for setting protein intake targets (often calculated per pound of lean mass rather than total body weight) and for tracking body composition changes during training.
Two people with the same total weight can have very different lean body mass, which is part of why weight alone is a limited measure of fitness or health compared to body composition.
About the Boer formula
The Boer formula is one of several equations used to estimate lean body mass from height, weight, and sex, and is generally considered reasonably accurate for people within a typical body composition range. Like all formula-based estimates, it becomes less precise at the extremes — very high muscle mass or very high body fat percentages.
More precise measurement methods, like DEXA scans or hydrostatic weighing, directly measure body composition rather than estimating it from a formula, making them more accurate for people who fall outside typical ranges.
Frequently asked questions
How is lean body mass different from muscle mass?
Lean body mass includes muscle, but also bone, organs, and water — it's a broader measure than muscle mass alone, which is why LBM is typically higher than an estimate of muscle tissue by itself.
Why does the formula use height as well as weight?
Height helps account for overall body frame size, improving the accuracy of the estimate compared to using weight alone.