Calculation of IBW in Hamilton Medical ventilators

Author: Kaouther Saihi, Thomas Laubscher, Reviewer: Bernhard Schmitt, Ralph Teuber

How is the ideal body weight (IBW) calculated in Hamilton Medical ventilators?

For adult and pediatric patients, Hamilton Medical ventilators use the sex and patient height to calculate the ideal body weight (IBW). There are two different formulae, depending on whether the patient is in the pediatric or adult patient group.


Our formula for the calculation of the IBW in children is based on the equation from Traub and Johnson [1]: IBW = 2.396*exp (0.01863*height).

  • Body height (BH) ≤ 70 cm: IBW = 0.125 x BH – 0.75
  • Body height > 70 but  ≤ 128: IBW = 0.0037 x BH^2 – 0.4018 x BH + 18.62


Our formula for the calculation of the IBW in adults is based on the equation from Knoben et al. [2], a variation of which in centimeters was used by Brower et al. [3].

  • IBW in males = 50 + 0.91 (centimeters of height - 152.4)
  • IBW in females = 45.5 + 0.91 (centimeters of height - 152.4)

Relevant software: HAMILTON-C6 SW v1.2.x; HAMILTON-C3 SW v2.0.x; HAMILTON-C1/T1/MR1 SW v2.2.x/3.0.x; HAMILTON-G5/S1 SW v2.8x


  1. Traub SL, Johnson CE. Comparison of methods of estimating creatinine clearance in children. Am J Hosp Pharm. 1980;37(2):195-201.
  2. Knoben JE, Anderson PO, eds. Handbook of clinical drug data. 7th ed. Hamilton, Ill.: Drug Intelligence, 1993.
  3. Acute Respiratory Distress Syndrome Network, Brower RG, Matthay MA, et al. Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med. 2000; 342(18):1301-1308. 
weight, ideal body weight, IBW, height, sex, patient group

Date of Printing: 30.06.2022
The content of this Knowledge Base is intended for use by Hamilton Medical distribution partners for informational purposes only, and should not be copied, distributed or published in any way. While the information contained herein is believed to be accurate, it does not represent an official recommendation from Hamilton Medical AG, nor may it substitute an opinion, assessment or instructions provided by a trained healthcare professional.
Date of Printing: 30.06.2022
The content of this Knowledge Base is intended for informational purposes only. Medin Medical AG provides no warranty with respect to the information contained in this Knowledge Base and reliance on any part of this information is solely at your own risk. For detailed instructions on operating your Medin Medical device, please refer to the official Medin Medical Operator’s Manual for the respective device.