Practice and Tools
Ideal Body Weight Calculator (Devine)
Estimate ideal body weight (IBW) in kilograms using the Devine equation — the reference formula for aminoglycoside and vancomycin weight-based dosing.
Enter values and press Calculate to see the result.
Enter height in cm or feet/inches and select sex; if an actual body weight is supplied, the tool also reports Adjusted Body Weight (AjBW = IBW + 0.4 x (actual - IBW)) for patients whose actual weight exceeds 120% of IBW.
Method: Devine
Inputs and units: Height (cm, or feet and inches); sex; actual weight (kg or lb, optional)
Assumptions and limitations: Devine's equation is not defined below 60 inches (152 cm); results are clamped to the base value and flagged. For underweight patients (actual < IBW), most dosing guidance uses actual body weight.
Primary reference: Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8(11):650-655.
Last reviewed: October 2026
Formula
Male: IBW (kg) = 50 + 2.3 x (height in inches - 60)
Female: IBW (kg) = 45.5 + 2.3 x (height in inches - 60)
Adjusted BW = IBW + 0.4 x (actual BW - IBW), used when actual exceeds 120% of IBW.
Clinical Notes
- AjBW is commonly used for aminoglycosides and vancomycin in obese patients; some drugs (e.g., enoxaparin prophylaxis) use actual body weight instead — always check the reference.
- Educational reference only. Not a substitute for a formulary or clinical judgment.
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