Lean Body Mass Calculator
Estimate fat-free mass with the Boer, James, and Hume formulas.
LBM = body weight minus fat mass. Boer is most common, James and Hume cross-check. None are as accurate as a DEXA scan, but they're useful for tracking change over time using the same formula.
About
Lean body mass is your weight minus fat mass. This tool runs three established formulas (Boer, James, Hume) so you can compare them. Useful for setting protein targets and tracking change over time on a cut or bulk.
How to use
- Enter sex, weight, and height.
- Read the LBM estimate from each formula.
FAQ
How accurate is this?+
These formulas estimate LBM from height and weight only, so they can't see actual body composition. A DEXA scan is far more accurate. But these are useful for tracking change, since the error is roughly constant if your formula stays the same.
Which formula should I use?+
Boer is the most common in fitness contexts. James and Hume cross-check it. Pick one and stick with it.