# Lean Body Mass Calculator

> Estimate lean body mass with Boer, James, and Hume adult equations or the Peters pediatric equation.

Page: https://askcalculators.com/calculator/lean-body-mass-calculator/
Definition: https://askcalculators.com/calculator/lean-body-mass-calculator/definition.json
JSON Schema: https://askcalculators.com/calculator/lean-body-mass-calculator/schema.json
Version: 2.0.0
Maintained by: AskCalculators (software project; not a credentialed reviewer)
Qualified review: pending. Automated checks do not establish professional approval.
Page status: Live
Review status: Pending

## Use
Open the calculator page and enter values. Query-string parameters can restore and bookmark a calculation.
Example: https://askcalculators.com/calculator/lean-body-mass-calculator/?mode=adult&unitSystem=metric&sex=male&age=30&weightKg=70&heightCm=175

## Inputs
- mode: Equation group; type=select; required; default=adult; values=adult|child
- unitSystem: Units; type=select; required; default=metric; values=metric|imperial
- sex: Sex used by equation; type=select; required; default=male; values=male|female
- age: Age; type=number; required; default=30; min=13; max=120
- weightKg: Weight; type=number; required; default=70; min=1; max=500; showWhen=unitSystem:metric
- heightCm: Height; type=number; required; default=175; min=50; max=300; showWhen=unitSystem:metric
- weightLb: Weight; type=number; required; default=154; min=2; max=1100; showWhen=unitSystem:imperial
- feet: Height feet; type=number; required; default=5; min=1; max=9; showWhen=unitSystem:imperial
- inches: Height inches; type=number; required; default=9; min=0; max=11.9; showWhen=unitSystem:imperial

## Outputs
- average: Average adult estimate; format=text; primary
- boer: Boer estimate; format=text
- james: James estimate; format=text
- hume: Hume estimate; format=text
- peters: Peters child estimate; format=text
- leanPercent: Lean mass percentage; format=percent

## Formula
Adult equations: Boer, James, and Hume use sex-specific weight and height coefficients; Peters estimates extracellular volume and multiplies it by 3.8.

## Rules
- Empty optional inputs are undefined, not zero.
- Hidden conditional inputs are ignored.
- Do not invent missing required inputs.

Notice: Lean-body-mass equations are population estimates and may be inaccurate for children, pregnancy, edema, or unusual body composition.