About this Lean Body Mass
Knowing your Lean Body Mass (LBM) is crucial for setting accurate protein goals, calculating drug dosages, and tracking true fitness progress. Unlike simple weight, LBM represents the metabolically active tissue in your body—muscle, organs, bone, and water—excluding body fat.
Who this calculator is for
- People who want a weight metric that separates lean mass from total body weight.
- Lifters and athletes setting protein or cutting targets from body-composition estimates.
- Anyone comparing lean mass against body fat, BMI, or calorie tools.
When to use it
- Use this calculator when total scale weight feels too incomplete.
- Use it to estimate lean-mass-based protein or performance goals.
- Use it to compare progress during fat loss while preserving muscle.
How to use this calculator
- Select your Gender (formulas differ due to body composition).
- Enter your Height in cm.
- Enter your Weight in kg.
- The result is your LBM in kg.
Key assumptions
- The estimate relies on predictive formulas rather than direct body-composition scans.
- Inputs such as height, weight, sex, and body fat are used as simplified proxies for lean tissue.
- Real lean mass can differ when hydration, training status, or measurement quality changes.
Accuracy and testing
Review formula sources, default test cases, assumptions, unit handling, rounding rules, and changelog for this calculator.
How this calculator works
Inputs explained
Gender
Men typically carry more skeletal muscle mass than women of the same height.
Height/Weight
Used to statistically predict body composition based on population averages.
Understanding your results
Example scenarios
Average Male
Height 180cm, Weight 80kg. LBM ≈ 61.4 kg. (Est. Body Fat ~23%)
Average Female
Height 165cm, Weight 60kg. LBM ≈ 44.9 kg. (Est. Body Fat ~25%)
Key Features
- Boer Formula Accuracy
- Metabolic Relevance
- Body Fat Estimate
Things to Keep in Mind
Predictive formulas are averages. Extremely muscular individuals (bodybuilders) may have their LBM underestimated.
Tips & Best Practices
- To maintain LBM while losing weight, prioritize resistance training and adequate protein intake.
- Sudden drops in LBM usually indicate water loss or muscle catabolism, not fat loss.
- For athletes, LBM is a better metric for sizing than BMI.
Glossary of Terms
- Fat-Free Mass
- Synonym for Lean Body Mass. Everything in the body that isn't adipose tissue.
- Boer Formula
- A widely respected formula derived from CT scan data used to estimate LBM.