Lean Body Mass Calculator
Estimate your lean body mass from height and weight using the Boer, James and Hume formulas
Lean Body Mass Calculator
Estimate your lean body mass from height and weight using the Boer, James and Hume formulas
What Is Lean Body Mass and How Is It Estimated?
Lean body mass (LBM) is everything in your body that is not fat: muscle, bone, organs, skin and water. It is a better guide than total weight for setting protein targets, calculating drug doses and tracking the effect of training.
Without a scan, LBM can be estimated from height, weight and sex using published formulas. This calculator shows the Boer, James and Hume equations side by side and their average, together with the share of your body weight that is lean.
How to Use This Calculator
Why Lean Mass Is the Number to Track
Muscle drives strength, metabolic rate and long-term health, so knowing your lean mass gives a better picture of progress than the scale. Two people with the same weight can have very different lean mass and very different performance.
Lean mass is also the basis for several nutrition targets. Many athletes set protein intake per kilogram of lean mass, and some calorie estimates use lean mass rather than total weight.
?Frequently Asked Questions
No single formula is best for everyone. The Boer and Hume equations are widely used and tend to agree for average builds, while James can underestimate lean mass at high body weights. The average of the three is a reasonable starting point.
Lean body mass includes muscle plus bone, organs, connective tissue and body water. Muscle mass is only a part of it, so your muscle mass is lower than your lean mass.
Yes. Many sports nutrition guides suggest around 2 to 3 grams of protein per kilogram of lean mass for people training hard, which is why lean mass is a useful base. Use the protein calculator for a full recommendation.
Formula estimates use only height, weight and sex, while smart scales use electrical impedance and DEXA uses X-rays. Each method has its own error, so compare the same method over time rather than across methods.
It is your total weight minus the estimated lean mass. For most people that is mostly body fat, but it includes small amounts of essential fat.
No. They were developed for adults. Growth and development change body composition, so use age-appropriate tools and clinical advice for young people.