There are a few reasons why you might want to use a lean body mass calculator. Have you ever wondered why slim but muscular people may weigh more than plump ones? We’ve all heard people say “muscle weighs more than fat”, but is that really true? What does the muscle weight depend on? If you want an answer to these questions, you should know how to calculate lean body mass (LBM).
Lean body mass (LBM) is a part of body composition that is defined as the difference between total body weight and body fat weight. This means that it counts the mass of all organs except body fat, including bones, muscles, blood, skin, and everything else. While the percentage of LBM is usually not computed, it on average ranges between 60-90% of total body weight. Generally, men have a higher proportion of LBM than women do. The dosages of some anesthetic agents, particularly water-soluble drugs, are routinely based on the LBM. Some medical exams also use the LBM values. For body fitness and routine daily life, people normally care more about body fat percentage than LBM. To compute body fat, consider using our body fat calculator or ideal weight calculator.
Multiple formulas have been developed for calculating estimated LBM (eLBM) and the calculator above provides the results for all of them.
How to calculate lean body mass
There are multiple lean body mass equations (and they vary between sexes as well). We’re using the Boer formula, which is said to be the most accurate.
LBM (men) = 0.407 * weight [kg] + 0.267 * height [cm] – 19.2
LBM (women) = 0.252 * weight [kg] + 0.473 * height [cm] – 48.3
However, if you know your fat concentration, you can determine your exact LBM, according to this simple formula:
Lean Body Mass = Body Weight – (Body Weight * Body Fat %)
You will need to:
- Measure your body weight
- Multiply your body weight by the fat percentage
- Subtract the result from your body weight
Why is it important to know how much lean body mass you have? For one thing, your body-fat percentage is a better indicator of overall health and fitness than the scale alone. Body mass index (BMI) charts often erroneously list muscular individuals as obese—even though they have a low body-fat percentage—simply because they have more lean body mass.
You can also use your lean body mass as a benchmark for assessing progress so you can fine-tune your macronutrients to build muscle. Many calculators use it in determining how many grams of protein you need to maintain and build muscle.
Yes, you do need to eat more calories to build muscle, but eating alone won’t do the trick. Resistance training creates microtears in the muscle fibers, which your body then repairs to create bigger, stronger muscles.
Once you know your body-fat percentage and lean body mass, calculate your calorie needs with our calorie calculator. Remember that to lose weight you need to create a calorie deficit, and to gain weight you need a calorie surplus, but to gain muscle you need to add resistance training.