Lean Body Mass Calculator
Estimate lean body mass (LBM), fat mass, and lean percentage using body fat % or popular formulas (Boer, James, Hume).
What is lean body mass?
Lean body mass (LBM) is your total body weight minus fat mass. It includes muscle, bone, organs, connective tissue, and body water. LBM is often used for fitness tracking and for estimating calorie needs, medication dosing, and performance metrics.
Lean body mass formulas explained
Formula-based methods like Boer, James, and Hume estimate lean mass using only height and weight. If you know your body fat percentage, the body fat method is usually the most direct way to compute LBM.
Lean body mass vs body fat percentage
Body fat percentage tells you how much of your body weight is fat. Lean mass percentage tells you how much is lean tissue. Because the formulas use different assumptions, results can vary—use the comparison view to see a reasonable range.
Frequently Asked Questions
Quick answers about lean body mass.
What is lean body mass?
Lean body mass is total body weight minus fat mass.
How do you calculate lean body mass?
If you know body fat %, LBM = weight × (1 − body fat%/100). Otherwise, use formulas based on height and weight.
What is the difference between lean body mass and muscle mass?
Lean body mass includes muscle plus bone, organs, connective tissue, and water. Muscle mass is only the muscle portion.
Which lean body mass formula is best?
There is no single best formula. Use the comparison mode to see the range across Boer, James, and Hume.
Is this lean body mass calculator accurate?
It provides estimates only. Accuracy depends on measurement quality and individual body composition.
Disclaimer
This calculator provides estimates for informational purposes only and does not provide medical advice. Consult a qualified professional for personalized guidance.