Lean Body Mass (LBM) Calculator

Calculate lean muscle mass, fat mass, and body fat % using Boer, James, and Hume clinical formulas.

Overview

Calculates Lean Body Mass (LBM)—the weight of bones, organs, muscles, and water excluding adipose fat tissue—using Boer, James, and Hume clinical formulas.

Formula & Calculation Method

Boer Formula (Men) = (0.407 × Weight) + (0.267 × Height) - 19.2 | Women = (0.252 × Weight) + (0.473 × Height) - 48.3

Weight in kg, height in cm. Lean body mass represents total metabolically active tissue and serves as the baseline for protein and drug dosing.

Worked Example: Male Weighing 80 kg at 180 cm Height (Boer Formula)

Inputs: Sex = Male | Weight = 80 kg | Height = 180 cm

  • Weight component = 0.407 × 80 = 32.56
  • Height component = 0.267 × 180 = 48.06
  • Constant subtraction = -19.2
  • Lean Body Mass = 32.56 + 48.06 - 19.2 = 61.42 kg
  • Fat mass = 80 kg - 61.42 kg = 18.58 kg (23.2% Body Fat)

Summary: Total Weight = 80 kg | Lean Muscle/Organ Mass = 61.4 kg | Fat Mass = 18.6 kg | Fat % = 23.2%

Common Use Cases

  • Sports Nutrition: Calculate daily protein targets based on active lean tissue rather than total body weight.
  • Anesthetic Dosing: Determine accurate induction dosages for lipid-insoluble anesthetic agents.
  • Athletic Sarcopenia Screening: Monitor skeletal muscle retention in aging adults and cutting athletes.

Frequently Asked Questions

What is the difference between lean body mass and muscle mass?

Lean body mass includes all non-fat tissue (bones, water, organs, and muscles); skeletal muscle mass is just one component of LBM.

How does LBM affect my calorie needs?

Lean body mass is your primary metabolically active tissue; individuals with higher LBM burn significantly more calories even while resting.

Can you increase lean body mass while losing fat?

Yes, 'body recomposition' is achievable, particularly in beginners, returning lifters, or individuals with higher body fat using progressive overload and high protein.

Related Calculators & Tools