Your measurements
Your measurements stay in this browser. Results are informational estimates, not medical advice.
How to use the Lean Body Mass Calculator
Enter the requested values and review the calculation as a planning estimate.
Enter your details
Enter sex, units, weight and height. Optionally add a body-fat percentage.
Review the calculation
Compare the Boer, James and Hume estimates and any direct body-fat result.
Interpret with context
Use the formula range as context; lean mass includes more than muscle.
Frequently Asked Questions
What does lean body mass include?
This calculator provides an informational estimate based on the values and method you select.
Which lean body mass formulas are used?
The result uses the displayed calculation method and updates when you change the inputs.
Why can the formula estimates differ?
Individual circumstances and measurement differences can affect how the estimate should be interpreted.
Is lean body mass the same as muscle mass?
Use the result as a planning reference rather than a diagnosis, prescription, or guarantee.
Can I use a body-fat percentage instead?
Choose the unit that matches your measurement wherever a unit selector is available.
How should I measure height and weight?
For the most useful comparison, enter recent measurements and use consistent input units.
Is this a medical body-composition assessment?
Seek advice from an appropriately qualified professional for personal medical, nutrition, or training decisions.