Lean body mass calculator

Estimate lean body mass with Boer, James and Hume, with an optional comparison from a known body-fat percentage.

Profile and measurements

Boer (1984) is the primary result. James and Hume are shown alongside it so you can see the spread between methods.

Sex used by the formulas
Height

If you already have a reliable estimate, enter it to calculate weight × (1 − body fat %).

Method & sources

Boer is the primary result because it is a later published anthropometric equation than Hume and James and is widely reused for height-and-weight lean-mass estimation. James and Hume remain visible to show model variability. If body-fat percentage is entered, a fourth value is calculated directly from body weight without replacing Boer.

Formula
Boer — Male: LBM = 0.407 × weight(kg) + 0.267 × height(cm) − 19.2 · Female: 0.252 × weight + 0.473 × height − 48.3. James — Male: 1.10 × weight − 128 × (weight/height)² · Female: 1.07 × weight − 148 × (weight/height)². Hume — Male: 0.32810 × weight + 0.33929 × height − 29.5336 · Female: 0.29569 × weight + 0.41813 × height − 43.2933. With BF%: LBM = weight × (1 − BF%/100).

Limitations

  • These equations predict average composition from height, weight and sex in their source cohorts; they do not directly measure your tissues.
  • Error can increase for very muscular builds, extreme body sizes, pregnancy, people under 18 and some clinical situations.
  • Lean body mass must not be interpreted as muscle mass or used on its own for medical decisions or medication dosing.

Sources