Enter your gender, age, height, and body weight to calculate your Lean Body Mass (LBM) — the weight of everything in your body except fat. Results are shown using three established formulas: Boer, James, and Hume, so you can compare estimates side by side.
Lean Body Mass (Boer)
--
Lean Body Mass (James)
--
Lean Body Mass (Hume)
--
Body Fat % (Boer)
--
Body Fat % (James)
--
Body Fat % (Hume)
--
Lean Body Mass is the total weight of your body minus all fat tissue. It includes muscles, bones, organs, blood, skin, and water. On average, LBM accounts for 60–90% of total body weight, with men typically having a higher proportion than women.
Each formula was developed by different researchers using different study populations and regression methods. The Boer formula tends to give slightly higher LBM estimates, while Hume is often the most conservative. Comparing all three gives you a reasonable range rather than relying on a single estimate.
These formula-based calculators provide reasonable estimates but are not as accurate as clinical methods like DEXA scans or hydrostatic weighing. They are useful for general fitness tracking and health monitoring, but individual results may vary based on body type and composition.
Men and women have different average body compositions — men typically carry more muscle mass and less body fat at the same height and weight. The formulas use different coefficients for male and female inputs to account for these physiological differences.
LBM percentage is the inverse of body fat percentage. A healthy body fat range for men is generally 10–20% and for women 18–28%, meaning healthy LBM percentages would be roughly 80–90% for men and 72–82% for women.
The most effective way to increase LBM is through resistance or strength training combined with adequate protein intake. Maintaining a slight caloric surplus while doing progressive overload training helps build muscle without adding excessive fat.
Some medications, especially water-soluble drugs and certain anesthetics, are dosed based on lean body mass rather than total weight. Using total body weight for these drugs could result in overdosing in individuals with higher body fat percentages.
No — Lean Body Mass includes everything in your body except fat: muscles, bones, organs, blood, skin, and water. Muscle mass is only one component of LBM. Some people mistakenly use the terms interchangeably, but they are distinct measurements.