What is lean body mass?

It's total body weight minus fat mass — including muscle, bone, organs, and water.

How is lean body mass estimated?

Common formulas (like Boer or James) estimate it using height, weight, and sex, though DEXA scans give more precise measurements.

Why use lean body mass instead of total weight for dosing or nutrition?

Certain medications and nutrient needs correlate more with metabolically active tissue than total weight, which includes fat.

Lean Body Mass Calculator - CalculatorLabs.net

Lean Body Mass Calculator

Estimate the weight of everything in your body that isn't fat, using the Boer formula.

Gender

Weight (kg)

Height (cm)

Lean Body Mass -

Estimated Fat Mass -

LBM as % of Total Weight -

What Is the Lean Body Mass Calculator?

Lean Body Mass (LBM) is your total body weight minus fat mass — it includes muscle, bone, organs, and body water. This calculator uses the widely-used Boer formula, a practical estimate based only on weight and height.

Formula Used

Men: LBM = 0.407×Weight + 0.267×Height − 19.2
Women: LBM = 0.252×Weight + 0.473×Height − 48.3

Weight is in kilograms and height is in centimeters. This is an estimate — DEXA scans or bioelectrical impedance scales give more precise body composition readings.

How to Use This Calculator

Select your gender.
Enter your weight in kilograms.
Enter your height in centimeters.
Click Calculate to see your estimated lean body mass and fat mass.

Worked Example

A 75 kg man who is 178 cm tall has LBM = 0.407×75 + 0.267×178 − 19.2 = 30.5 + 47.5 − 19.2 = 58.8 kg. His estimated fat mass is 75 − 58.8 = 16.2 kg, meaning about 78% of his body weight is lean mass.