Lean body mass calculator
Lean body mass is everything that is not fat. Drug dosing, especially in anaesthesia, often scales with it rather than with total weight.
%
Lean body mass (Boer)
56.02kg
- Lean body mass (James)
- 56.52
- Lean body mass (Hume)
- 52.81
- Lean mass from your measured body fat
- 57.40
- Fat mass from your measured body fat
- 12.60
Show the working
- Weight = 70
- Height = 175
- Sex = 1
- Measured body fat (optional) = 18
- Lean body mass (Boer) = 1 > 0 ? 0.407*70 + 0.267*175 - 19.2 : 0.252*70 + 0.473*175 - 48.3 = 56.015
- Lean body mass (James) = 1 > 0 ? 1.1*70 - 128*(70/175)^2 : 1.07*70 - 148*(70/175)^2 = 56.52
- Lean body mass (Hume) = 1 > 0 ? 0.32810*70 + 0.33929*175 - 29.5336 : 0.29569*70 + 0.41813*175 - 43.2933 = 52.8092
- Lean mass from your measured body fat = 70 * (1 - 18/100) = 57.4
- Fat mass from your measured body fat = 70 - 57.4 = 12.6
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- Boer, men: LBM = 0.407 W + 0.267 H - 19.2
- Boer, women: LBM = 0.252 W + 0.473 H - 48.3
- James, men: LBM = 1.1 W - 128 (W/H)^2
- Hume, men: LBM = 0.32810 W + 0.33929 H - 29.5336
- W in kilograms, H in centimetres.
The three formulas were fitted to different populations and diverge at the extremes of weight; Boer is the most widely used.
This is a population formula, not a diagnosis. Individual metabolism, body composition and medical history all move the real answer, so treat the number as a starting point and talk to a clinician about anything that matters.