What is it?
The Lean Body Mass Calculator estimates your Lean body mass (everything except fat: muscle, bone, organs, water), its Share of weight, and Body fat (by difference).
Who is it for?
Fitness enthusiasts setting protein targets, people tracking whether weight loss is fat or muscle, and students.
How to use it
Choose your Sex and enter Weight and Height. It uses the Boer formula: an estimate from height and weight. The answer appears as you type; there is no Calculate button. Tap Copy result to copy it, or Share on WhatsApp to send it.
How accurate is it?
- Formulas from height and weight can’t see how muscular you are. For athletes or people with obesity, they can be off by several kg.
- For a better estimate, use the Body Fat Calculator (tape measurements) and subtract fat mass from weight. Lab methods (DEXA scans) are the most accurate.
Uses
- Protein targets: some plans set protein per kg of lean mass instead of total weight.
- Tracking whether weight loss comes from fat or muscle over time.
- Doctors use lean mass to dose some medicines; never adjust medicines yourself.
This is general information to help you understand your numbers, not medical advice. Talk to a doctor about your own health.
Errors and how to fix them
- Odd result: check weight is in kg and height in cm.
Open the tool: Lean Body Mass Calculator
Still stuck?
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Questions, or an error not listed here?
Tell us in the comments: what you were doing, the exact message you saw, and your device and browser. We read every comment and add new fixes to this article.