Lean Body Mass Calculator
Calculate your lean body mass and fat-free weight using multiple formulas.
A lean body mass calculator estimates the weight of everything in your body except fat, including muscle, bone, organs, and water.
Examples
170 lb, 5'9" male
Frequently Asked Questions
What is lean body mass?
Why does LBM matter?
Quick Tips
- •Track your lean body mass over time to monitor changes in body composition rather than just total weight.
- •Combine LBM estimates with body fat percentage for a more complete picture of your fitness.
- •Use LBM to set more accurate protein intake targets — aim for 1.6-2.2g per kg of lean mass for muscle building.
A lean body mass calculator estimates the weight of everything in your body except fat, including muscle, bone, organs, and water.
How to Use This Calculator
Enter your weight, height, and gender. The calculator estimates your lean body mass using three formulas (Boer, James, Hume) and shows the average. It also calculates your estimated fat mass and body fat percentage.
Understanding the Formula
Boer: Male LBM = 0.407W + 0.267H - 19.2; Female LBM = 0.252W + 0.473H - 48.3. James and Hume formulas use similar regression-based approaches with different coefficients.
Examples
170 lb, 5'9" male
Weight: 77 kg, Height: 175 cm. Boer: 0.407(77) + 0.267(175) - 19.2 = 59.5 kg. Average LBM across all formulas: approximately 62 kg (137 lbs).
Frequently Asked Questions
What is lean body mass?
Lean body mass is your total body weight minus all fat weight. It includes muscle, bone, organs, water, and other non-fat tissue. It is not the same as muscle mass alone.
Why does LBM matter?
LBM is used to calculate medication dosages, estimate metabolic rate, and set nutritional targets. Higher LBM relative to total weight generally indicates better fitness and metabolic health.
Assumptions & Limitations
- Based on population averages; individual results vary with genetics and training history.
- Formulas are less accurate for very lean or very overweight individuals.
- Does not distinguish between muscle mass and other non-fat tissues like bone and water.