Lean Body Mass Calculator
Find out how much of your body weight is muscle, bone, organs and water — everything that isn’t fat — and see your estimated body fat percentage.
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Lean body mass includes muscle, bone, organs, and water — essentially everything in your body that isn’t fat. It’s commonly used to guide protein intake, dosing, and training goals.
How Lean Body Mass Is Calculated
Lean Body Mass (LBM) is your total body weight minus your fat mass — it covers muscle, bone, organs, skin, and body water. This calculator offers three well-established formulas that estimate LBM from your height and weight.
All three formulas rely on height and weight, since body composition scanning (like DEXA) isn’t practical for everyday use. The Boer formula is widely cited as a solid general-purpose estimate for most adults.
Frequently Asked Questions
What exactly does lean body mass measure?
Lean body mass is everything in your body that isn’t fat — muscle, bone, organs, skin, and the water contained in all of those tissues. It typically makes up 60–90% of total body weight depending on body fat levels.
How is LBM different from muscle mass?
Muscle mass is only one part of LBM. Lean body mass also includes bones, organs, skin, and body water, so it will always be a larger number than your muscle mass alone.
Why would I want to know my LBM?
LBM is often used to set protein intake targets, track body composition changes over time independent of the scale, and estimate metabolic rate more precisely than weight alone allows.
Which formula should I use?
The Boer formula is generally recommended as a reliable all-purpose estimate. Hume and James are included for comparison, since results can vary slightly by a few percent between formulas, and none of them replace a direct body composition scan like DEXA or BIA.