Endotracheal tube size for children (Age 1 to 8 years)


Uncuffed endotracheal tube size   mm (ID)
Cuffed endotracheal tube size   mm (ID)

  • Select an uncuffed tube with an internal diameter of 3.5 mm for infants up to 1 year of age.
  • A cuffed ETT with an internal diameter of 3.0 mm may be used for infants more than 3.5 kg. and <1 year.
  • ID stands for internal diameter. For patients 2 years and older, the age parameter is rounded to provide an endotracheal tube size that is likely to pass through the vocal cords and have a tight enough seal for ventilation (uncuffed endotracheal tube) or to allow for ventilation after cuff inflation (cuffed endotracheal tube).
  • The cuffed tube equation is appropriate for low profile, thin walled cuffed endotracheal tubes.
  • As opposed to the cuffed endotracheal tube calculator above which applies to thin-walled low pressure cuffed endotracheal tubes, when using a regular cuffed endotracheal tube, select a tube one FULL size smaller than that determined by the uncuffed endotracheal tube formula.
  • Additional tubes one half size larger and one half size smaller than calculated should also be available during endotracheal intubation attempts regardless of whether an uncuffed or cuffed endotracheal tube is used.

Equations used
Uncuffed endotracheal tube size = Uncuffed endotracheal tube size
Cuffed endotracheal tube size = Cuffed endotracheal tube size
Uncuffed endotracheal tube size = 4 + (Age / 4)
Cuffed endotracheal tube size = 3.5 + (Age / 4)


  1. King BR, Baker MD, Braitman LE, et al. Endotracheal tube selection in children: a comparison of four methods. Ann Emerg Med. 1993 Mar;22(3):530-4. PubMed ID: 8442540 PubMed Logo
  2. Khine HH, Corddry DH, Kettrick RG, et al. Comparison of cuffed and uncuffed endotracheal tubes in young children during general anesthesia. Anesthesiology. 1997 Mar;86(3):627-31; discussion 27A. PubMed ID: 9066329 PubMed Logo
  3. Wheeler, M, Cote, CJ, Todres, ID. The pediatric airway. In: Cote C, Lerman J, Todres ID (Eds). A Practice of Anesthesia for Infants and Children, 4th ed. Saunders-Elsevier, Philadelphia 2009. p.237. NLMN ID: 101482651 NCBI Logo
  4. Kleinman ME, de Caen AR, Chameides L, et.al. Pediatric basic and advanced life support: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations. Pediatrics. 2010 Nov;126(5):e1261-318. PubMed ID: 20956433 PubMed Logo



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