Body sizePharmacy

Ideal & Adjusted Body Weight (Devine)

Calculates Devine ideal body weight and, when actual weight is provided, adjusted body weight for dosing in obesity.

Enter the required values to see the result.

Formula

\text{IBW}_{male} = 50 + 2.3 \times (\text{height in inches} - 60) \qquad \text{IBW}_{female} = 45.5 + 2.3 \times (\text{height in inches} - 60) \qquad \text{AjBW} = \text{IBW} + 0.4 \times (\text{ABW} - \text{IBW})

For heights below 5 ft (152.4 cm), 2.3 kg per inch is subtracted from the base — a common practical convention; the equation is least reliable at short stature.

Caveats & limitations

Historically derived from estimates rather than measurement; treat as a convention, not a physiological constant.
Least reliable at short stature (<152 cm / 5 ft).
Some protocols use correction factors other than 0.4, or lean body weight equations (e.g. Janmahasatian) — follow local policy.

Evidence & UK guidance

Primary evidence

Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650–655.

UK practice

Devine IBW underpins many UK dosing policies (aminoglycosides, and Cockcroft–Gault in obesity). Adjusted body weight (IBW + 0.4 × excess) is commonly used when actual weight exceeds ~120–130% of IBW; follow local policy, which varies between trusts.

Formula and citations last verified: 2026-08-03

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