Lean Body Mass Calculator
Calculate lean tissue weight and body fat mass using Boer, James, and Hume clinical equations.
LBM Results
Medical disclaimer. This calculator is for general information and education only. It is not medical advice, not a diagnosis, and not a substitute for professional care. Lean mass equations estimate from height, weight and sex rather than measuring anything. Where the figure matters clinically, DEXA is the reference method.Speak to a doctor or another qualified clinician about any health decision.Last reviewed .
Frequently asked questions
What is Lean Body Mass (LBM)?
Lean Body Mass is the weight of your body minus all fat tissue. It includes muscle, bones, water, and organs.
What is lean body mass?
Everything that is not fat: muscle, bone, organs, connective tissue and body water. It is usually 60-90% of total weight depending on body fat. Fat-free mass is a near synonym, though strictly lean body mass includes the small amount of essential fat inside organs and cell membranes.
Which lean body mass formula is best?
Boer is generally the most reliable for adults across a wide weight range; James and Hume are older alternatives that tend to under-read at higher body weights. All three are regressions on height and weight, so none can detect whether your particular build is muscular or not - a measured body fat percentage gives a better answer.
Why does lean body mass matter?
It drives your resting metabolic rate, it is the tissue that strength training builds, and it is the denominator for some drug dosing. During weight loss, preserving lean mass through adequate protein and resistance training is what keeps metabolic rate from falling further than the weight loss alone would explain.