Lean Body Mass Calculator

Lean body mass (LBM) is your total body weight minus all fat mass. It includes muscles, bones, organs, blood, skin, and water. LBM is important for calculating drug dosages, nutritional needs, and fitness metrics. It's also used to estimate basal metabolic rate.

Lean body mass includes everything that's not fat: muscles, bones, organs, water, connective tissue. Muscle mass is just the skeletal muscle component — typically 40–50% of LBM. LBM is always larger than muscle mass.

Higher LBM means higher resting metabolism (muscles burn more calories at rest). It's also used to set protein targets (g per kg of LBM), prescribe exercise loads, and track real body composition changes independently of weight fluctuations from water.