Your Lean Body Mass
What is Lean Body Mass (LBM)?
Lean Body Mass is the total weight of your body minus the weight of fat mass. It includes muscles, bones, organs, water, and connective tissue. Knowing your LBM is valuable for tracking fitness progress, setting protein intake, and understanding body composition beyond the number on the scale.
How to Use This Calculator
- Using Formula: Enter your gender, weight, height, and choose a formula (Boer, James, or Hume). Switch between metric and imperial units as needed.
- Using Body Fat %: If you know your body fat percentage (from calipers, smart scale, or DEXA scan), simply enter it along with your weight.
- Results are shown in both kilograms and pounds for easy interpretation.
Lean Body Mass Formulas Explained
Boer Formula – one of the most widely used in clinical settings:
- Men: LBM = (0.407 × weightkg) + (0.267 × heightcm) − 19.2
- Women: LBM = (0.252 × weightkg) + (0.473 × heightcm) − 48.3
James Formula – derived from a large population study, often cited in research:
- Men: LBM = 1.1 × weightkg − 128 × (weightkg / heightcm)²
- Women: LBM = 1.07 × weightkg − 148 × (weightkg / heightcm)²
Hume Formula – another validated equation, especially for Western populations:
- Men: LBM = (0.32810 × weightkg) + (0.33929 × heightcm) − 29.5336
- Women: LBM = (0.29569 × weightkg) + (0.41813 × heightcm) − 43.2933
All formulas provide an estimate. Individual results vary; for medical accuracy consult a professional.
Why Lean Body Mass Matters
LBM helps you assess whether weight changes come from fat loss or muscle gain. A higher lean body mass generally indicates better metabolic health and physical performance. Use it alongside body fat percentage to get a complete picture of your body composition.
