Lean Body Mass Calculator | Fitness Calculator


Lean Body Mass Calculator

While we keep fussing about body weight, very few of us give importance to Lean Body mass which demands equal attention for leading a long healthy life. Lean body mass is directly associated with your BMR. Hence, greater the LBM, greater the BMR which ultimately strengthens the body and guards it against obesity and common health related issues.

This useful tool helps to measure your Lean Body Mass in a few easy steps by using certain details such as gender, height, weight etc. It also helps to keep track of your LBM on a constant basic


It can be very useful to know your lean body mass. It’s a great indicator of overall health, adding some much-needed detail to more conventional measures of weight like BMI. It can help you to decide on your health and fitness goals- if you’re looking to lose weight, build muscle or maintain a healthy body composition, it will be the measure by which you plan a great deal.

But what is it, and how is lean body mass calculated? Let’s take a look.



Lean body mass is your overall weight minus your weight from bodyfat. Basically, if you subtract the weight that comes from fat (your body fat percentage) from your total weight, you will have your lean body mass.

Knowing this can help those looking to lose weight maintain their weight loss purely from fat. If you can keep your lean body mass stable whilst bringing your overall weight down, you will know that you’re only losing fat- not muscle or bone density, as is often the case.

Alternatively, those looking to put on weight in the form of muscle will want to build their lean mass at the same rate as their overall weight. This will show them that, although they are gaining total weight, they are not putting on any extra bodyfat.

To find out your lean body mass, you often need to know your body fat percentage, though we will run through some methods below in which this isn’t the case. Some of the methods of lean body mass calculation are more accurate than others, whilst some are more accessible, though we will run through these all shortly.



There are two main ways in which lean body mass is calculated. There is often a trade-off between accessibility and accuracy, with the most accurate methods being beyond many people.



This is arguably the most accessible, crudest way of finding out your lean body mass. There is a simple formula you can use for which you will only need your weight and height. Use the equations below, with all weights in kg and all heights in cm.

  • For men: Lean body mass = (0.32810 × W) + (0.33929 × H) − 29.5336
  • For women: Lean body mass = (0.29569 × W) + (0.41813 × H) − 43.2933

It should be noted that this will be quite inaccurate but may work well as a rule of thumb or best guess in the first instance.

For an easier version of this, you can always choose an online calculator for lean body mass.



You can also use your body fat percentage to work out your lean body mass, as mentioned above. Divide your percent body fat by 100 to make it a decimal. Then multiply this number by your total weight.

For example, if you weigh 80kg and have learned that your body fat percentage is 15%, multiply 80 x 0.15. This is your fat mass in kilograms (800 x 0.15 = 12kg). The simply subtract this from your total weight to get your lean body mass. Here, we are looking at 80 - 12 = 68kg of lean body mass.

The tricky part here is finding out your body fat percentage. The techniques below will all enable you to do so but the trade-off mentioned above comes into play: generally, the more accurate the method, the less accessible it is to most people.

Methods of finding out your body fat percentage include:



Use skin fold callipers on a range of points on your body. You will pinch skin and measure the thickness, then simply put these numbers into a conversion table or calculator for lean body mass.

Many personal trainers at your local gym will be well-practiced in this technique. It’s not the most accurate method but is easy and relatively reliable and consistent.




Again, your local gym may offer this facility. A bioelectrical scale is a set of scales with electrodes that you stand on, and/or grip in your hands, as they send a gentle electrical current through your body. As muscle and fat conduct electricity differently, they will tell you everything you need to know. They are safe, though not always accurate (other factors, like hydration, can sometimes skew readings).



This is where we get very accurate and very inaccessible. Hydrostatic weighing involves a comparison between your weight on land to your weight while completely submerged in water. A technician can then calculate your body fat percentage.

As before, it’s very reliable: however, it involves large amounts of specialist kit, will not be available at your local gym, and can cost a fair amount.

What is lean body mass?

Lean body mass is a measure of the weight of your blood, bones, ligaments, tendons, internal organs and muscles minus your fat weight. Due to the presence of necessary fat within the bone marrow and internal organs, lean mass does include a small amount of essential fat.Having a high percentage of lean mass boosts your metabolism so it's easier to maintain an overall healthy weight.

How to calculate lean body mass?

There are multiple ways of determining lean body mass through mathematical formulas. We are using the Boer formula, which is considered to be the most accurate.


For men: LBM = (0.407 × W) + (0.267 × H) − 19.2

For women: LBM = (0.252 × W) + (0.473 × H) − 48.3

where W is body weight in kilograms and H is body height in centimeters.

How to use LBM calculator?

The LBM calculator is a simple yet effective tool which helps you to determine your lean body mass. In order to get accurate results, you need to follow the below mentioned steps:

  1. Check and enter your weight in either imperial or metric system which are both supported by the calculator.
  2. Enter your age.
  3. Measure and enter your height.
  4. Measure your neck at the narrowest point, waist and hips. Enter these measurements in the calculator. Click Calculate to get your results.

Lean body mass chart

Lean body mass usually ranges from 60 to 90 percent of body weight. A woman with a lean body mass percentage of less than 68 percent would be considered unhealthy, as would a man with less than 75 percent lean body mass. Refer to the LBM chart for a better idea.

GenderAgeLow(-)Normal(0)High(+)Very High(++)

18-39<24.324.3 - 30.330.4 - 35.3≥35.4
40-59<24.124.1 - 30.130.2 - 35.1≥35.2
60-8<23.923.9 - 29.930.3 - 34.9≥35.0

18-39<33.333.3 - 39.339.4 - 44.0≥44.1
40-59<33.133.1 - 39.139.2 - 43.8≥43.9
60-8<32.932.9 - 38.939.0 - 43.6≥43.7

Is lean body mass the same as muscle mass?

Though the two terms are often used interchangeably, they are not the same. LBM is inclusive of Muscle mass and your bone and bodily fluid mass. Whereas, Muscle Mass is the weight of your muscles which include the cardiac, smooth, and skeletal muscles.

How do I increase lean body mass?

Here are 5 useful tips to increase lean body mass:

  1. Don’t crash diet: Crash diets are rarely a quick solution to fat loss. Extreme diets increase muscle protein breakdown and result in almost five times the loss of lean body mass. It is wiser to cut down on your calorie intake by about 800 to 1,000 calories which will help you to lose up to 45 percent of your fat.
  2. Time your Protein intake: Your body builds lean body mass through protein at different rates throughout the day. As per our body systems protein breakdown happens more in the day. An evening high protein meal keeps you going a long way and curbs the urge to binge on calories. 
  3. Have a pre and after-work out snack: Prior to and after completing your workout, go for a combination of protein and carbohydrates. The pre-workout snack fuels and prepares your body for the workout. The after- work out snack resupplies your body with energy exhausted during the exercise and provides protein to repair your muscles.
  4. Exercise: Include two to three days of strength training and weight lifting each week. Aim for a mix of isotonic and isometric exercises in your fitness regimen to increase lean muscle. 
  5. Add a Protein supplement to you regular diet: Muscles need proteins to fuel their growth. A protein shake or protein bar boosts your progress in gaining lean body mass.

What foods to avoid when trying to gain muscle?

Hitting the gym is not enough, look at what you are eating before you measure your progress. Your diet plays a crucial part in determining your muscle gains.

Here’s a list of foods that hinder muscle development:

  1. Too much protein shake is not good as the body will then tend to convert the excess protein into fat and not muscles.
  2. Avoid alcohol. Alcohol not only disturbs the way your body makes protein but also slows down muscle recovery. Plus, the excess carbohydrates only help to reverse your progress.
  3. Sugary foods that are high in fat and low in protein are better avoided.
  4. Whereas lean natural meats and fish make for a solid diet, processed meats are no good.
  5. No junk food. While they maybe tempting, consuming these foods may inadvertently hinder your progress.

How long does it take to build lean muscle?

Lean muscles can be built through consistent weight lifting and strength training sessions and by providing your body with the fuel and nutrients necessary to heal and grow. However, men are likely to notice faster results than women as they are pumped by testosterone and the growth hormone. But if you are consistent with your workouts and follow a systematic muscle building routine, you should start to see results in about six to eight weeks. More time will be necessary to see more significant changes in your muscle sizes.