Fitness & Health

Lean Body Mass (Boer, James, Hume)

Estimate your lean body mass with three validated clinical formulas. You get each result side by side, an average, and your derived fat mass.

How to use
  1. Enter your weight and height.
  2. Select your sex.
  3. Check the averaged LBM and the fat-mass split.
Try
Lean body mass (3-formula average)

Boer + James + Hume, averaged

Boer (clinical)
James (W/H ratio)
Hume (1966)
Fat mass (avg)
Estimates for general wellness, not medical advice. Check with a doctor or dietitian before acting on health figures.
Was this helpful?

How it's calculated

LBM = average of Boer, James and Hume estimates

Boer (men) = 0.407·W + 0.267·H − 19.2; James = 1.10·W − 128·(W/H)²; Hume = 0.328·W + 0.339·H − 29.5. W = weight (kg), H = height (cm); women use the female coefficients. Body fat = W − LBM.

Common questions

What is lean body mass?

It is your total weight minus your fat mass, covering muscle, bone, organs, and water.

Why three formulas?

Boer, James, and Hume each estimate slightly differently, so seeing all three gives a more reliable range than any single one.