Lean Body Mass Calculator
Calculate your lean body mass (LBM) using multiple formulas including Boer, James, and Hume. Free LBM calculator to determine muscle mass and body fat percentage for fitness tracking.
Body Composition
Detailed Breakdown
| Total Body Weight | 75 kg |
| Lean Body Mass | 62.5 kg (83.3%) |
| Fat Mass | 12.5 kg (16.7%) |
| Formula Used | Boer |
Formula Comparison
| Formula | LBM |
|---|---|
| Boer Formula (Recommended) | - |
| James Formula | - |
| Hume Formula | - |
What is Lean Body Mass?
Lean Body Mass (LBM) is your total body weight minus your body fat. It includes the weight of your muscles, bones, organs, water, and everything else that isn't fat. LBM is a crucial metric for fitness enthusiasts, athletes, and anyone tracking their body composition.
Unlike Body Mass Index (BMI), which only considers height and weight, LBM gives you a clearer picture of your actual body composition by distinguishing between muscle mass and fat mass.
LBM Calculation Formulas
Boer Formula (Recommended)
The Boer formula (1984) is one of the most accurate and widely used formulas for estimating lean body mass. It takes into account gender differences in body composition.
Male: LBM = 0.407 × Weight(kg) + 0.267 × Height(cm) - 19.2
Female: LBM = 0.252 × Weight(kg) + 0.473 × Height(cm) - 48.3
James Formula
The James formula (1976) is another established method that provides accurate estimates based on weight and height, with gender-specific calculations.
Hume Formula
The Hume formula (1966) is a classic equation that has been validated through numerous studies and provides reliable LBM estimates.
Why is Lean Body Mass Important?
- Accurate Calorie Needs: Your LBM is the primary determinant of your basal metabolic rate
- Fitness Progress: Track muscle gain and fat loss more accurately than weight alone
- Protein Requirements: Daily protein needs are calculated based on LBM, not total weight
- Health Assessment: LBM is a better indicator of health than BMI alone
- Training Goals: Understanding your body composition helps set realistic fitness goals
Tips for Improving Lean Body Mass
- Strength training 3-4 times per week to build muscle mass
- Consume adequate protein (1.6-2.2g per kg of LBM for muscle building)
- Progressive overload - gradually increase training intensity
- Get sufficient sleep (7-9 hours) for muscle recovery and growth
- Maintain a slight calorie surplus when building muscle
- Stay consistent with training and nutrition
- Track your progress regularly to monitor changes
- Consider working with a trainer for proper exercise form
Important Notes
- These formulas provide estimates - actual body composition may vary
- For most accurate results, measure body fat percentage using methods like DEXA scan, hydrostatic weighing, or calipers
- If you don't know your body fat %, the formulas will estimate LBM based on height, weight, and gender
- Athletes and very muscular individuals may have higher LBM than formulas predict
- LBM naturally decreases with age (sarcopenia) starting around age 30
- Women typically have lower LBM and higher body fat % than men at the same weight
- Hydration levels can affect body composition measurements
- Use multiple measurements over time to track trends rather than focusing on single values