Find out how much of your weight is lean tissue versus fat using the Boer formula.
Frequently Asked Questions
Lean body mass (LBM) is everything in your body that is not fat — muscles, bones, organs, water, and connective tissue. It is also called fat-free mass. Knowing your LBM helps set accurate protein targets and track body composition changes over time.
This calculator uses the Boer formula (1984), which estimates LBM from height and weight. For men: LBM = 0.407 x weight(kg) + 0.267 x height(cm) - 19.2. For women: LBM = 0.252 x weight(kg) + 0.473 x height(cm) - 48.3. It is one of the most validated estimation formulas.
The Boer formula provides a reasonable estimate but cannot replace direct measurement methods like DEXA scans, hydrostatic weighing, or BIA devices. It tends to be most accurate for individuals of average body composition and may overestimate LBM in those with high body fat.
LBM is a better indicator of metabolic health than total body weight. Higher LBM means a higher basal metabolic rate, better insulin sensitivity, and greater functional strength. Tracking LBM helps you ensure you are gaining muscle rather than just weight.
For men, a healthy lean body mass percentage is typically 70-90% of total weight (10-30% body fat). For women, 65-85% is typical (15-35% body fat). Athletes often have higher LBM percentages due to greater muscle mass and lower body fat.
Measure monthly. If your weight stays the same but LBM increases, you are successfully recomposing — gaining muscle while losing fat, which is the ideal outcome.