Lean body mass (LBM) is your total weight minus fat mass, including muscle, bone, organs, and water. This calculator estimates it with the Boer formula.
Sample input: Weight (kg): 70, Height (cm): 175, Sex (1 = male, 0 = female): 1
Lean body mass: 56 (Boer formula estimate)
Your estimated lean body mass is 56 kg (80% of body weight) for a male, leaving about 14 kg of fat mass, using the Boer formula.
Lean body mass is everything in your body that is not fat: muscle, bone, organs, connective tissue, and water. It is your total body weight minus fat mass.
It uses the Boer formula (1984), a validated equation that estimates lean body mass from weight, height, and sex. It is widely used in clinical and research settings.
Lean mass drives your resting metabolism and strength, and it is used to dose some medications. Preserving lean mass during weight loss helps keep metabolism higher and supports long-term health.
Progressive resistance training combined with adequate protein (commonly 1.4 to 2.0 grams per kilogram for active people) and sufficient calories is the most effective way to build and maintain lean mass.