Calculate your estimated lean body mass (LBM) using multiple scientific formulas including Boer, James, and Hume. Get accurate body composition analysis.
Choose between US (lbs/inches) or Metric (kg/cm) units
Select gender and enter your age
Enter your height and weight in chosen units
Compare lean body mass estimates from multiple formulas
Lean body mass (LBM) is a component of body composition that is defined as the difference between total body weight and body fat weight. This means that it counts the mass of all organs except body fat, including bones, muscles, blood, skin, and everything else. While the percentage of LBM is usually not computed, it typically ranges between 60-90% of total body weight. Generally, men have a higher proportion of LBM than women do.
The dosages of some anesthetic agents, particularly water-soluble drugs, are routinely based on the LBM. Some medical exams also use the LBM values. For body fitness and routine daily life, people normally care more about body fat percentage than LBM. To compute body fat, consider using our body fat calculator or ideal weight calculator.
Multiple formulas have been developed for calculating estimated LBM (eLBM) and the calculator above provides the results for all of them.
Male: eLBM = 0.407W + 0.267H - 19.2
Female: eLBM = 0.252W + 0.473H - 48.3
Where W = weight in kg, H = height in cm
Male: eLBM = 1.1W - 128(W/H)²
Female: eLBM = 1.07W - 148(W/H)²
Where W = weight in kg, H = height in cm
Male: eLBM = 0.32810W + 0.33929H - 29.5336
Female: eLBM = 0.29569W + 0.41813H - 43.2933
Where W = weight in kg, H = height in cm
eECV = 0.0215·W0.6469·H0.7236
eLBM = 3.8·eECV
Applicable for children aged 13-14 years or younger
Where W = weight in kg, H = height in cm, eECV = estimated extracellular volume
Lean body mass and fat free mass are often used interchangeably. While this is unlikely to cause issues in most cases, the two are not exactly the same.
Fat free mass is calculated as the difference between total body mass and all fat mass including essential fat. This is the difference between fat free mass and lean body mass. Subtracting the mass of essential fat from lean body mass yields fat free mass. The difference between lean body mass and fat free mass amounts to approximately a 2-3% difference in men and 5-12% difference in women.
Used to calculate appropriate dosages of certain medications, particularly water-soluble anesthetic agents that distribute based on lean body mass rather than total body weight.
Helps track muscle mass gains, monitor body composition changes during training, and assess progress in building lean muscle tissue.
Used to determine caloric needs, protein requirements, and macronutrient ratios for optimal muscle maintenance and growth.
Employed in clinical research, nutritional studies, and sports science for body composition analysis and metabolic research.
Important: While these formulas provide useful estimates, professional body composition analysis using methods like DEXA scans, bioelectrical impedance, or hydrostatic weighing provide more accurate measurements for medical or precision fitness applications.
Track muscle mass gains and monitor body composition changes during training programs.
Calculate appropriate medication dosages based on lean body mass for certain drugs.
Determine caloric needs and macronutrient ratios based on lean body mass.
Assess body composition for athletes in sports where weight and power are important factors.
Monitor changes in body composition for overall health and wellness tracking.
Used in clinical research and nutritional studies for body composition analysis.
Lean body mass (LBM) is the total weight of your body minus all the weight due to your fat mass. It includes muscles, bones, organs, water, and everything else that's not fat. LBM typically ranges from 60-90% of total body weight.
This calculator uses multiple scientific formulas: Boer, James, and Hume formulas for adults, and Peters formula for children aged 14 or younger. Each formula uses different combinations of weight, height, gender, and age to estimate LBM.
While often used interchangeably, lean body mass includes essential fat in organs, while fat-free mass excludes all fat including essential fat. The difference is typically 2-3% in men and 5-12% in women.
Each formula was developed using different populations and methodologies. The Boer formula uses regression equations, James uses a more complex calculation, and Hume was developed from a specific study population. Results may vary based on your individual body composition.
These formulas provide estimates based on statistical models. For precise measurements, professional methods like DEXA scans, bioelectrical impedance, or hydrostatic weighing should be used. These calculations are best for general fitness tracking and comparisons.
Explore more free online calculators and utilities from our collection:
Disclaimer: This calculator provides estimated lean body mass values using established scientific formulas. Results are for informational purposes only and may vary from actual measurements taken by medical professionals. For precise body composition analysis, consult with healthcare providers or use professional measurement equipment.