Lean Body Mass Calculator

Created by Mateusz Mucha, Piotr Małek and Łucja Zaborowska, MD, PhD candidate
Reviewed by Bogna Szyk and Jack Bowater
Based on research by
Boer P. Estimated lean body mass as an index for normalization of body fluid volumes in humans. American Journal of Physiology (October 1984)
Last updated: Jun 10, 2022

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).

You'll find out:

  • What lean body mass is
  • How to calculate lean body mass
  • How to use the LBM Calculator

What is lean body mass?

Lean body mass is what your body would weight if you didn't have any body fat; that means it counts all the organs, bones, muscles, blood and skin, and everything else which is not fat but has mass.

It is particularly important to know your lean body mass if you are trying to lose weight. By watching your LBM you can monitor how much muscle you are losing. If you are only losing the muscle, the effect of your diet may be very disappointing, as losing muscle very often results in unpleasant appearance. Knowing how to calculate your lean body mass also helps you decide how much fat you should lose and what your body fat percentage will be after that. It is much more accurate to consider your LBM than your body weight.

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:

  1. Measure your body weight
  2. Multiply your body weight by the fat percentage
  3. Subtract the result from your body weight

How to use LBM calculator?

Lean body calculator is a useful tool which enables you to find your lean body mass. You simply need to type in your weight and height. Then, the calculator will estimate two versions of LBM - the first one for men and the second one for women.

Let's take an example:
Weight: 50
Height: 165

The calculator shows about 45 kg of NBM if you are a man and about 42 kg if you are a woman. The difference between genders is down to genetics. The male body generally contains more muscle while the female body naturally has more body fat.

Other considerations

The LBM Calculator you can also find your body fat percentage. However, instead of subtracting the values, you can check our body fat calculator or ideal weight calculator.

In order to find out if your body fat percentage is healthy or not, you can use the BMI calculator. This tool calculates if you are underweight, overweight or just right. As LBM is closely connected with metabolism we also recommend basal metabolic rate calculator. It uses your age, height, weight and gender to estimate how many calories you would need if you were to spend the whole day resting. It's an excellent indicator of your metabolism levels. You can also determine your body composition that adjusts for skeletal mass, by using our body frame size calculator.


Is a lean body mass equal to 79% of my weight healthy?

Yes, a lean body mass between 60% and 90% of your body weight is considered healthy. This range varies depending on many factors, one of which is sex. A woman's minimum healthy lean body mass is slightly lower than that for men (68% and 75%, respectively).

What is my lean body mass if I weight 75 kg and I'm a 180 cm tall male?

About 59 kg. To calculate the lean body mass, follow these steps:

  1. Measure your weight and height.
  2. Plug these values in the lean body mass formula for males:
    LBM (men) = 0.407 × weight [kg] + 0.267 × height [cm] - 19.2

The result is:
LBM = 0.407 × 75 + 0.267 × 180 = 59.39 kg

What is lean body mass?

Lean body mass is the difference between an individual's total body weight and their weight of body fat. The lean body mass is an important quantity both for fitness and medicine. During weight loss, estimating the lean body mass help greatly in tracking your progress; on the other hand, nutrients and drugs are better dosed when you consider the fat-free mass, as fat is not metabolically active.

How do I calculate my lean body mass?

There are multiple empirical formulas used to calculate lean body mass. The most accurate one is the Boer formula, which requires your weight in kilograms and height in centimeters.

The formula differs for men and women: choose accordingly or you may get incorrect results.

LBM (men) = 0.407 × weight [kg] + 0.267 × height [cm] - 19.2

LBM (women) = 0.252 × weight [kg] + 0.473 × height [cm] - 48.3

Mateusz Mucha, Piotr Małek and Łucja Zaborowska, MD, PhD candidate
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