Lean Body Mass (LBM)
Estimate lean body mass using the Boer formula (1984), separating fat-free mass from total body weight.
Results
What is it?
Lean Body Mass (LBM) estimates your fat-free mass — muscles, bones, organs, and water — using the Boer formula (1984). It separates what you weigh without fat from your total body weight, which is important for body composition analysis and anaesthesia dosing.
How to use
Enter your weight (kg or lb), height (cm or in), and biological sex. Males: LBM = 0.407 × weight + 0.267 × height − 19.2. Females: LBM = 0.252 × weight + 0.473 × height − 48.3. The calculator also returns fat mass and lean mass percentage.
Example scenario
A 75 kg, 175 cm male: LBM = 0.407 × 75 + 0.267 × 175 − 19.2 = 30.5 + 46.7 − 19.2 = 58.0 kg. Fat mass = 17.0 kg, lean percentage ≈ 77.3%.
Pro tip
The Boer formula is preferred over the James formula at higher body weights because it avoids the paradoxical decrease in LBM seen with James in obese individuals. For propofol and other lipophilic drug dosing, LBM-based calculations reduce the risk of overdose.