Determine your body's fat-free mass. Knowing your Lean Body Mass is essential for accurately planning your nutritional needs, especially protein intake.
Lean Body Mass (LBM) represents the weight of everything in your body except for fat. This includes your muscles, bones, organs, skin, and water. Understanding your LBM is more insightful than just tracking body weight, as it helps you see if you're losing fat while preserving muscle during a diet.
This calculator uses the Boer formula, a widely recognized method for estimating LBM.
Disclaimer: This calculator provides an estimate for educational purposes and should not be considered medical advice. Consult a healthcare professional for a comprehensive health evaluation.
Maintained by Live Fitness Check. Last updated: August 9, 2026. How we test our calculators .
Estimates the portion of body weight that is not fat mass.
The calculator converts the entered measurements and applies the lean-body-mass equation implemented in the live tool. The calculation uses sex, height and weight.
Formula-based lean-mass estimates are approximations and can differ from measured body composition. Use the number as an estimate and consider professional advice when the result may affect health, treatment, pregnancy, nutrition, exercise safety or another important decision.
