Last updated: 2026-06-21

Adjusted Body Weight

Adjusted body weight is a dosing weight for people who weigh noticeably more than their ideal. It blends ideal and actual weight so that calculations — chiefly drug doses for certain medications in overweight and obese adults — do not overshoot. This calculator first finds ideal body weight from the Devine formula, then applies the standard adjustment.

Ideal body weight first

The Devine formula sets a reference weight from height and sex, counting every inch above five feet:

$\mathrm{IBW}_{\text{men}} = 50 + 2.3 \times (\text{height in inches} - 60)$

$\mathrm{IBW}_{\text{women}} = 45.5 + 2.3 \times (\text{height in inches} - 60)$

The adjustment

$\mathrm{ABW} = \mathrm{IBW} + 0.4 \times (\text{actual weight} - \mathrm{IBW})$

Only 40% of the weight above ideal is added. The reasoning is that excess tissue is largely fat, which holds less of many water-soluble drugs than lean tissue, so dosing on full actual weight would give too much.

Worked example

When it applies

Whether to dose on actual, ideal, or adjusted weight depends on the specific drug, so the choice follows the medication reference rather than a universal rule. When actual weight equals ideal, the adjusted value collapses back to the ideal weight. For the reference weight on its own see the Ideal Weight Calculator, and for a dosing-related clearance estimate the Creatinine Clearance Calculator.