Lean Body Mass Calculator

LBM = Total body weight - Fat mass. It includes muscle, bone, organs, blood, and everything except body fat. LBM is important for determining appropriate drug doses, calculating BMR, setting protein intake goals, and tracking fitness progress (you can gain muscle while losing fat even if scale weight stays constant).

Muscle is metabolically active — more muscle means higher calorie burn at rest. Tracking LBM (rather than just weight) gives a clearer picture of body composition changes. It is possible to lose fat and gain muscle simultaneously, which looks like no progress on the scale but represents significant health improvement.

Average LBM for men: 60-70kg (130-155 lbs). Average LBM for women: 40-50kg (88-110 lbs). Higher is generally better (up to a point) as it correlates with strength, metabolic health, and reduced injury risk. LBM naturally declines with age (sarcopenia) — resistance training helps preserve it.

These formulas were developed from population averages and are estimates. Error range: typically ±3-5 kg from actual LBM. For more accurate measurement, use DEXA scan (most accurate), hydrostatic weighing, or air displacement plethysmography (Bod Pod). Bioelectrical impedance scales are convenient but less accurate.

Most evidence suggests 0.7-1.0g protein per pound (1.5-2.2g per kg) of LBM for active individuals trying to build or preserve muscle. Example: 150 lbs LBM = 105-150g protein/day. Higher end of the range for those doing intense strength training or trying to gain muscle.