Calculate your lean body mass (weight excluding fat) using the Boer formula. Enter your sex, height and weight to see lean mass, fat mass and lean body percentage.
Choose your unit system, then enter your sex, height in cm (metric) or feet & inches (imperial), and weight in kg (metric) or pounds (imperial). The calculator applies the Boer formula to find your lean body mass, fat mass and lean percentage.
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A lean body mass calculator estimates how much of your weight is lean tissue (muscle, bone, organs, water) rather than fat, using the Boer formula — useful for tracking muscle gain and dosing some medications.
Fat mass = total weight − lean mass; lean % = lean mass ÷ weight × 100.
Lean body mass is the kilograms of non-fat tissue; body fat percentage is fat as a share of total weight. They're two views of the same split — the body-fat calculator focuses on the fat side.
It's one of several validated estimation formulas (others include Hume and James). It's a good population estimate, but a DEXA scan or hydrostatic weighing is far more precise.