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Lean Body Mass Calculator

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Results

Lean Body Mass (LBM)
135.3 lbs
Estimated Body Fat: 18% (29.7 lbs fat)
Lean Mass: 82% Fat Mass: 18%
Comparison by Clinical Formula
Formula Lean Mass Fat Mass Fat %
From Body Fat %
 135.3 lbs (61.4 kg) 29.7 lbs 18%
Boer Formula (Standard)
 129.5 lbs (58.7 kg) 35.5 lbs 21.5%
James Formula
 131.5 lbs (59.6 kg) 33.5 lbs 20.3%
Hume Formula
 122 lbs (55.3 kg) 43 lbs 26%
Related: Body Fat • Army Body Fat • BMI • Ideal Weight

What is Lean Body Mass (LBM)?

Lean Body Mass is the total weight of your body minus the weight of your body fat. It consists of muscle, bone, skin, internal organs, and body water. Maintaining a high ratio of lean mass to fat mass is correlated with longevity and metabolic health.

Boer Formula (1984)

Currently considered the most reliable anthropometric equation for estimating lean weight.

James Formula (1976)

Calculates lean body weight based on a quadratic relationship with body mass index.

Hume Formula (1966)

Developed by Hume to predict total body water from anthropometric dimensions.

Understanding your calculation

Method, example and limitations

How the calculation works

Lean body mass estimates the part of body weight that is not fat, using the selected equation or body-fat percentage. It includes water, bone and organs as well as muscle.

Example to check

If body weight is 80 kg and body fat is 25%, the non-fat portion is 80 × 0.75 = 60 kg.

Before using the result

Equation estimates can differ from measured body composition. Do not interpret lean mass as muscle mass alone or use it to diagnose a health condition.

Calculation methodology · Report a result that needs review