Lean Body Mass Calculator

The Lean Body Mass Calculator computes a person's estimated lean body mass (LBM) based on body weight, height, gender, and age. For comparison purposes, the calculator provides the results of multiple popular formulas.

feet   inches
Weight pounds
Height cm
Weight kg


The Boer Formula Result: 127.4 lbs.
The James Formula Result: 129.0 lbs.
The Hume Formula Result: 120.4 lbs.

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LBM is a part of body composition that is defined as the difference between total body weight and body fat weight. While the percentage of LBM is usually not computed, it is the complement of body fat percentage, and on average ranges between 60-90% of total body weight. Generally, men have a higher proportion of LBM than women do, and the dosages of some anesthetic agents, particularly water-soluble drugs, are routinely based on the LBM. Multiple formulas have been developed for calculating estimated LBM (eLBM) and the calculator above uses the following with the exception of the Peters formula (which is used to determine LBM for children).

Lean Body Mass Formula for Adults

The Boer Formula:1

For males:
eLBM = 0.407×weight(kg) + 0.267×height(cm) - 19.2
For females:
eLBM = 0.252×weight(kg) + 0.473×height(cm) - 48.3

The James Formula:2

For males:
eLBM = 1.1×weight(kg) - 128×(
For females:
eLBM = 1.07×weight(kg) - 148×(

The Hume Formula:3

For males:
eLBM = 0.32810×weight(kg) + 0.33929×height(cm) - 29.5336
For females:
eLBM = 0.29569×weight(kg) + 0.41813×height(cm) - 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×weight(kg)0.6469×height(cm)0.7236
eLBM = 3.8×eECV

  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 Anaesthesia1 06(5): 719-23 (2011).