Lean Body Mass Calculator | Best Calculator

Lean Body Mass Calculator

Metric
US Units
kilograms (kg)
Please enter a valid weight (10-300 kg)
centimeters (cm)
Please enter a valid height (50-250 cm)
The lean body mass based on different formulas:
Formula Lean Body Mass Body Fat
Boer - -
James - -
Hume - -
Formulas and Examples:

Boer Formula:
For men: LBM = (0.407 × weight) + (0.267 × height) - 19.2
For women: LBM = (0.252 × weight) + (0.473 × height) - 48.3
Example (Male): For 70kg, 175cm → (0.407×70) + (0.267×175) - 19.2 = 28.49 + 46.725 - 19.2 ≈ 56.0kg
Example (Female): For 60kg, 165cm → (0.252×60) + (0.473×165) - 48.3 = 15.12 + 78.045 - 48.3 ≈ 44.9kg

James Formula:
For men: LBM = (1.1 × weight) - 128 × (weight/height)²
For women: LBM = (1.07 × weight) - 148 × (weight/height)²
Example (Male): For 70kg, 175cm → (1.1×70) - 128 × (70/175)² = 77 - 128 × 0.16 ≈ 56.5kg
Example (Female): For 60kg, 165cm → (1.07×60) - 148 × (60/165)² = 64.2 - 148 × 0.132 ≈ 44.6kg

Hume Formula:
For men: LBM = (0.32810 × weight) + (0.33929 × height) - 29.5336
For women: LBM = (0.29569 × weight) + (0.41813 × height) - 43.2933
Example (Male): For 70kg, 175cm → (0.32810×70) + (0.33929×175) - 29.5336 ≈ 22.967 + 59.376 - 29.534 ≈ 52.8kg
Example (Female): For 60kg, 165cm → (0.29569×60) + (0.41813×165) - 43.2933 ≈ 17.741 + 68.991 - 43.293 ≈ 43.4kg

Peters Formula (for children ≤14):
LBM = 3.8 × (0.0215 × weight⁰·⁶⁴⁶⁹ × height⁰·⁷²³⁶)
Example (Child): For 40kg, 140cm → 3.8 × (0.0215 × 40⁰·⁶⁴⁶⁹ × 140⁰·⁷²³⁶) ≈ 3.8 × (0.0215 × 7.37 × 27.45) ≈ 3.8 × 4.34 ≈ 16.5kg
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Understanding Lean Body Mass (LBM)

What is Lean Body Mass?

Lean body mass (LBM) is a key component of your body composition. It’s calculated by subtracting the weight of your total body fat from your total body weight. Essentially, LBM encompasses the mass of all your body’s organs and tissues excluding fat. This includes your bones, muscles, blood, skin, and everything else. While the percentage of LBM isn’t typically calculated directly, it generally makes up between 60% and 90% of your total body weight. Men tend to have a higher proportion of LBM compared to women. In the medical field, the dosage of certain anesthetic drugs, particularly those that are water-soluble, is often determined based on a patient’s LBM. Some medical examinations also utilize LBM values. However, for general fitness and everyday life, most people are more interested in their body fat percentage than their LBM. If you’d like to calculate your body fat, you can use our dedicated body fat calculator or ideal weight calculator.

Our calculator above provides estimated LBM (eLBM) results using several different formulas that have been developed over time.

Lean Body Mass Formulas for Adults

The Boer Formula:1

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

The James Formula:2

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

The Hume Formula:3

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

Lean Body Mass Formula for Children

The Peters Formula:4

The author suggests that this formula is applicable for children aged 13-14 years old or younger. The formula is used to compute an eLBM based on an estimated extracellular volume (eECV) as follows:

eECV = 0.0215·W0.6469·H0.7236
eLBM = 3.8·eECV

In the formulas above, W is the body weight in kilogram and H is the body height in centimeter.

Lean Body Mass vs. Fat Free Mass: What’s the Difference?

The terms “lean body mass” and “fat free mass” are frequently used interchangeably, and in many situations, this won’t cause any confusion. However, it’s important to understand that they aren’t precisely the same.

Lean body mass includes the combined weight of your bones, muscles, water, ligaments, tendons, and internal organs. Importantly, internal organs contain a certain amount of essential fat, and the weight of this essential fat is included when measuring lean body mass. While internal organs also have surrounding subcutaneous fat (fat under the skin), this subcutaneous fat is not included in the measurement of lean body mass.

Fat free mass, on the other hand, is calculated as the difference between your total body weight and all fat mass, including essential fat. Therefore, the key difference between fat free mass and lean body mass lies in the inclusion of essential fat associated with internal organs.

To find your fat free mass, you would essentially subtract the weight of essential fat from your lean body mass. The typical difference between lean body mass and fat free mass is relatively small, estimated to be around 2-3% in men and 5-12% in women.

References:

  1. Boer P. “Estimated lean body mass as an index for normalization of body fluid volumes in man.” Am J Physiol 1984; 247: F632-5
  2. James, W. “Research on obesity: a report of the DHSS/MRC group” HM Stationery Office 1976
  3. Hume, R “Prediction of lean body mass from height and weight.”. J Clin Pathol. 1966 Jul; 19(4):389-91.
  4. A. M. Peters, H. L. R. Snelling, D. M. Glass, N. J. Bird “Estimation of lean body mass in children”. British Journal of Anaesthesia 106(5): 719-23 (2011).

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