This calculator is used to find the amount of lean body mass a person holds.

Lean body mass will be the type of body tissue that includes everything other than body fat.

This means the tissues such as muscle, bones, blood, skin, etc. It just excludes the body fat we hold.

The calculator we use will actually give the results from three formulas. These formulas are known as the Boer, James, and Hume formulas. They will all give somewhat similar results, but one will be better than the others, as there is generally a gold standard equation.

While the primary uses will be for adults looking into their health stats, there is also a formula for people that are under 15 years old. This is due to the slightly different needs that these groups have.

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So, make sure you use your gender, age, height, and weight to ensure that you get the calculator to work properly.

Make sure to differentiate between the US and metric units, as we have options for both.

What Is Lean Body Mass?

Lean body mass will be an essential mass on the body, even though somebody fat is excluded and essential, too.

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Lean body mass comprises our tissues like bones, muscles, blood, and basically, all things in the body that are not body fat.

The average amount of lean body mass is about 60 – 90% of your total body weight. The remaining percentages will be body fat percentages.

This lean body mass calculator works to find the weight of lean body mass you have, and it gives the body fat percent, along with the percent of lean tissues.

We can change these percentages over time by losing or gaining weight. In fact, they are basically always changing as we work out and eat unless we do everything exactly the same day in and day out.

Any changes in lean body mass will cause changes and new percentages to come out for body composition.

There are some clinical ways to find lean body mass and muscle mass specifically, but these will be a bit more expensive and take a good amount of time and training to have tested properly.

That is why we have these equations in the calculator here.

These calculators will only give you a close estimate, so if you want anything closer, you will need other methods of finding percentages. You could even use other calculators to compare, like a body fat calculator.

If you can calculate your body fight, you can know that the remaining weight percentage would be your lean body weight.

How Do We Calculate Lean Mass?

For these calculations, we will use three different ones for adults and one for children aged 14 and under.

Let’s show these 4 different equations.

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The 3 that exist for adults are the Boer, James, and Hume formulas.

The Boer formula is:

  • For males: eLBM = 0.407 W + 0.267 H – 19.2
  • For females: eLBM = 0.252 W + 0.473 H – 48.3

The Hume formula is:

  • For males: eLBM = 0.32810 W + 0.33929 H – 29.5336
  • For females: eLBM = 0.29569 W + 0.41813 H – 43.2933

The James formula is:

  • For males: eLBM = 1.1 W – 128 (W / H) ^2
  • For females: eLBM = 1.07 W – 148 (W / H) ^2

For Children, the formula is called the Peters formula, which is:

  • eECV = 0.0215 x W ^0.6469 x H x ^0.7236
  • eLBM = 3.8 x eECV

This children’s formula is optimal for anyone aged 14 or under. It is different since the amount of lean body mass changes so much throughout your lifetime, especially in times of massive growth, which these ages are going through.

For all of the formulas, we know that W is the body weight in kg and H is the body height in centimeters. So, if you do this independently, make sure you convert.

These are formulas used in medical settings, as the amount of lean body mass and body fat will matter when dosages are considered for surgeries or other medical scenarios.

We prefer to pay attention to the Boer formula, which is the first one on our list, and it is generally a middle ground between the James and Hume formulas.

How Can I Build Muscle?

When it comes to controlling this lean body mass and making changes to your amount, you don’t have too many options for tissues.

So, it will be easier for body tissues to change the amount of body fat and muscle, as you can’t train your body to gain significant weight in the other types of tissue.

Gaining muscle is the healthiest option for changing your percent of lean body mass, as well as losing body fat.

We can do both of these options by working out and eating properly.

The amount of muscle you can gain in any amount of time is less than the amount of body fat you can lose.

By adding muscle to the body, we will increase other health aspects, such as the basal metabolic rate and overall total daily expenditure.

Lean muscle is going to be gained by partaking in properly programmed resistance training, and over time the strength training will allow for long-term muscle growth and increase the overall weight of your lean mass.

Fat mass will typically decrease in times of caloric deficits, which are the opposite of what it takes to gain muscle.

So, we must consider the types of fitness and health goals we have for our bodies.

We hope that this article has helped you with your fitness and nutrition goals!

Make sure that you check out the other fitness calculators that we have here on PTPioneer.

Tyler Read - Certified Personal Trainer with PTPioneer

Tyler Read


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