Lean Body Mass Calculator
Estimate your lean body mass and fat mass using the Boer formula.
Fill in your details, then check your personalized result and recommendations.
Formula
Boer (men): LBM = 0.407·kg + 0.267·cm − 19.2
Worked example
Man 80 kg, 180 cm → LBM ≈ 61.5 kg
What the lean body mass calculator does
Lean body mass (LBM) is the total weight of everything in your body that is not stored fat — your muscle, bone, organs, and body water. This calculator estimates your LBM and fat mass from your weight, height, and sex, giving you a clearer picture of your body composition than the scale alone.
How the calculation works
The tool uses the Boer formula, a validated predictive equation with separate coefficients for men and women. It estimates lean mass from weight and height; subtracting that figure from your total weight gives your fat mass, and the ratio gives your lean mass percentage.
How to interpret your result
A higher lean mass percentage generally reflects better body composition and a higher resting metabolic rate, because muscle is metabolically active tissue. During a fat-loss phase, the goal is to lose fat mass while preserving lean mass. Tracking LBM over time tells you whether your training and nutrition are protecting muscle.
Health recommendations
Resistance training and adequate protein are the two most important tools for building and maintaining lean mass. Avoid aggressive crash diets, which tend to strip muscle along with fat. Use this with the Body Fat and Protein Intake calculators to plan training and recovery.
FAQ
+What is lean body mass?
Everything in your body except stored fat — muscle, bone, organs, water and connective tissue.
+Why track lean body mass?
Preserving lean mass during weight loss keeps metabolism higher and improves body composition.
+Which formula is used?
The Boer formula, one of the most accurate predictive equations for lean mass.