Lean Body Mass Calculator
Estimate your lean body mass (everything except fat) from your height, weight, and sex using the Boer formula. Calculates privately in your browser.
Lean body mass
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Show the math
The Boer formula estimates lean mass from weight and height:
men: 0.407·kg + 0.267·cm − 19.2 · women: 0.252·kg + 0.473·cm − 48.3
Lean body mass is everything that is not fat, muscle, bone, organs, and water. Because this uses only height and weight it cannot see your real composition; if you know your body-fat percentage, weight × (1 − fat%) is more personal.
What this does
A lean body mass calculator estimates everything in your body except fat (muscle, bone, organs, and water) from your height, weight, and sex using the Boer formula.
How it works
The Boer formula estimates lean mass from your weight and height with sex-specific constants. Lean body mass is your total weight minus body fat, so tracking it shows whether weight changes come from fat or muscle.
How to use it
- Choose your sex and units.
- Enter your height and weight.
- Read your estimated lean body mass.
- Compare it over time to track changes.
Understanding your result
Formula estimates use only height and weight, so they cannot see your actual composition. If you know your body-fat percentage, multiplying weight by (1 − fat%) is more personal.
Example
An 80 kg man at 180 cm has an estimated lean body mass of roughly 64 kg by the Boer formula.
Sources & methodology
- NIH, Assessing Your Weight and Health Risk, Body composition basics
Last updated .
Frequently asked questions
What is lean body mass?
It is your total weight minus body fat, muscle, bone, organs, and water. Tracking it helps you tell whether weight changes are coming from fat or from muscle.
How is it calculated here?
The tool uses the Boer formula, which estimates lean mass from your weight and height with sex-specific constants. It is widely used and needs no body-fat measurement.
Why does it differ from body-fat methods?
Formula-based estimates rely only on height and weight, so they cannot see your actual composition. If you know your body-fat percentage, multiplying weight by (1 − fat%) is more personal.
Do you keep my numbers?
No. All math happens locally in your browser.
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