Lean Body Mass Calculator

The Lean Body Mass Calculator estimates how much of your body weight is lean tissue — muscle, bone, organs and water — as opposed to stored fat.

Knowing your lean body mass (LBM) is useful for setting protein targets, dosing certain calculations, tracking changes during a training or weight programme, and understanding body composition beyond a single number on the scale.

This tool uses the Boer formula, a widely cited equation that estimates lean mass from your weight in kilograms, your height in centimetres, and your sex.

Enter those three values and you instantly see your estimated lean mass, the remaining fat mass, and your lean mass as a percentage of total weight.

Because the inputs update the result live, you can experiment to see how a change in weight would shift the numbers.

Remember that all such formulas are population estimates: they assume average body composition and cannot account for individual differences in muscularity, hydration or frame.

For precise figures, methods like DEXA scanning are required.

Used as a guide, though, this calculator is a quick, private way to gauge body composition — every calculation runs locally in your browser, with nothing uploaded or stored.