Your Body Profile
Fill height & weight for Boer / James / Hume formulas. Input body fat % for direct accurate lean mass calculation.
Important Disclaimer
This Lean Body Mass Calculator provides population-based estimated lean mass using Boer, James and Hume clinical formulas, plus direct calculation from body fat percentage. LBM estimates are not a substitute for DXA scans, lab body composition testing or professional medical advice. Calculation errors may occur due to bone density, hydration, muscle distribution, age and genetics. Do not use results alone to adjust medication, diet or training plans without consulting a doctor, dietitian or certified fitness coach.
Your Lean Body Mass Results
Daily Recommended Protein Intake (Based on LBM)
About The Three LBM Formulas
- Boer (1984): Best for average adult men & women, widely used fitness standard
- James (1976): Better for strength athletes with high muscle mass
- Hume (1966): Gold standard for hospital medication dosage calculations
Lean Body Mass = All non-fat tissue (muscle, bones, organs, water) — different from pure skeletal muscle mass percentage.
LBM Calculator FAQ
How accurate are these LBM formulas?
Boer formula has ±3–5kg error for average adults. Direct body fat method is more precise if your body fat reading is accurate. DXA scan is the clinical gold standard for exact lean mass measurement.
Why calculate protein based on LBM instead of total weight?
Using total weight overestimates protein needs for people with high body fat. LBM-based targets only account for metabolically active muscle tissue for optimal muscle retention and growth.
Does LBM decrease with age?
Yes, sarcopenia causes 3–8% lean mass loss per decade after age 30. Progressive resistance training and sufficient protein can slow or reverse this decline.