Paediatric endotracheal tube size

Internal diameter (mm) = age/4 + 3.5 (cuffed) or age/4 + 4 (uncuffed), for children ≥ 2 years.

Age

years

Tube type

ETT internal diameter

5.0 mm

Formula

age / 4 + type

Notes

Round to the nearest 0.5 mm and keep one size above and below ready. Under 2 years: term neonate 3.0-3.5 uncuffed / 3.0 cuffed; infant 3.0-3.5 cuffed. Depth: see paeds-ett-depth.

References

Van de Voorde P, et al. European Resuscitation Council Guidelines 2021: Paediatric Life Support. Resuscitation 2021;161:327-87.

Calculators support, not replace, clinical judgement. Check inputs and units, and confirm doses with your unit protocol.