Lean Body Mass Calculator
About Lean Body Mass Calculator
What Is Lean Body Mass?
Lean Body Mass (LBM) is your total body weight minus all fat weight. It includes muscle, bone, organs, blood, water, and connective tissue. LBM is a more useful metric than total weight for assessing fitness progress because it tells you how much functional tissue you carry. Two people at the same weight can have drastically different lean mass levels. Tracking LBM helps ensure that weight loss comes from fat rather than muscle, and that weight gain during bulking comes from muscle rather than just fat accumulation.
How LBM Is Calculated
The Boer formula estimates LBM from height and weight without requiring body fat measurement: Men: LBM = 0.407 x weight(kg) + 0.267 x height(cm) - 19.2. Women: LBM = 0.252 x weight(kg) + 0.473 x height(cm) - 48.3. If you know your body fat percentage, the direct formula is simply: LBM = Weight x (1 - Body Fat %). Both methods are provided in this calculator.
How to Use This Calculator
Enter your weight, height, and gender for the Boer formula estimate. Optionally enter your body fat percentage for the direct calculation. The results show your estimated lean body mass, fat mass, and the ratio between them. This information is valuable for setting protein intake targets (often calculated per pound of lean mass), calibrating calorie needs, and monitoring progress during body recomposition.
Frequently Asked Questions
Why is lean body mass important?
LBM drives your metabolism (more lean mass means higher BMR), determines strength, and is a better indicator of health than total weight. Preserving lean mass during dieting is essential for long-term success.
Can I gain lean mass while losing fat?
Yes, this is called body recomposition. It is most achievable for beginners, those returning to training after a break, overweight individuals, and those using a moderate caloric deficit with high protein and resistance training.
How much lean mass can I gain per month?
Beginners can gain 1-2 pounds of lean mass per month with optimal training and nutrition. Intermediate lifters gain 0.5-1 pound per month. Advanced lifters gain even less. These rates vary by genetics, age, and sex.
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