Lean Body Mass James Formula Calculator
Estimate lean body mass using the classic James regression equation for metabolic and clinical analysis.
About the James LBM Formula
Published in 1976, the James formula applies a non-linear quadratic function to weight and height to model lean body mass distribution.
Formulas
- Men: LBM = 1.10 × Weight - 128 × [Weight / Height]2
- Women: LBM = 1.07 × Weight - 148 × [Weight / Height]2
Frequently Asked Questions
Why does the James formula include a quadratic term?
The squared weight-to-height ratio accounts for the accelerating proportion of adipose mass relative to lean tissue at higher body weights.
Does the James formula perform well in severe obesity?
At extreme BMIs (> 42 kg/m²), the quadratic term can overcompensate, making the Boer formula preferred for high adiposity.
Can athletes with high muscle mass use this equation?
Muscular athletes may find the formula underestimates their lean mass because it assumes high weight-to-height ratios stem from fat.
How does biological sex affect the equation constants?
The formula uses distinct empirical constants to account for higher baseline skeletal muscle and lower essential fat in males.
Calculate in three steps
- 1Enter your valuesUse the fields above and check the units shown beside each input.
- 2Run the calculationSelect Calculate to refresh the result with your latest values.
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