Body Weight
Formula
IBW
Estimated ideal body weight in (kg)
Males: IBW = 50 kg + 2.3 kg for each inch over 5 feet.
Females: IBW = 45.5 kg + 2.3 kg for each inch over 5 feet.
ABW
Estimated adjusted body weight in (kg)
If the actual body weight is greater than 30% of the calculated IBW, calculate the adjusted body weight (ABW):
ABW = IBW + 0.4 (actual weight - IBW)
The IBW and ABW are used to calculate medication dosages when the patient is obese.
This formula only applies to persons 60 inches (152.4 cm) or taller.
Reference
Devine BJ. Gentamicin therapy. Drug Intelligence & Clinical Pharmacy. 1974;8(11):650-655. doi:10.1177/106002807400801104
Bauer LA, Edwards WAD, Dellinger EP, Simonowitz DA. Influence of weight on aminoglycoside pharmacokinetics in normal weight and morbidly obese patients. European Journal of Clinical Pharmacology. 1983;24(5):643-647. doi:10.1007/bf00542215