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Adjusted Body Weight Calculator

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kg

Adjusted Body Weight

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About

The Adjusted Body Weight (AjBW) is used for drug dosing in obese patients (those with actual body weight > 120% of ideal body weight). Many drugs distribute into lean tissue, so using actual body weight would lead to overdosing, while using ideal body weight would lead to underdosing. The AjBW provides a compromise using a correction factor of 0.4. It is commonly used for aminoglycoside, vancomycin, and some chemotherapy dosing.

Formula

Adjusted Body Weight = IBW + 0.4 × (ABW − IBW)
Use AjBW when ABW > 120% of IBW
IBW = Ideal Body Weight, ABW = Actual Body Weight

Interpretation

ABW / IBW RatioDosing Recommendation
≤ 120%Use actual body weight
> 120%Use adjusted body weight

References

  1. Winter MA, et al. Pharmacology of commonly used analgesics and sedatives in the ICU: benzodiazepines, propofol, and opioids. Pharmacotherapy. 2012;32(7):604-612.
  2. Pai MP, Paloucek FP. The origin of the 'ideal' body weight equations. Ann Pharmacother. 2000;34(9):1066-1069.

FAQ

Related Calculators

IBW

Calculate ideal body weight using the Devine formula.

BMI

Calculate Body Mass Index from weight and height.

BSA

Calculate body surface area using Du Bois or Mosteller formula.

Disclaimer

For educational and informational purposes only. Not intended to replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional.