The Cardiovascular
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Paediatric endotracheal tube (ETT) size

Age-based estimate of tracheal tube internal diameter and insertion depth.

Paediatric endotracheal tube (ETT) size
Age
years
Complete the fields above to see the result.

When to use

  • Rapid pre-intubation estimate of tube size and depth in a child older than about 1 year.

Formula

Uncuffed ID (mm) = age/4 + 4; cuffed ID (mm) = age/4 + 3.5; oral insertion depth (cm) = age/2 + 12.

Pearls and pitfalls

  • Have half-size tubes above and below the estimate immediately available.
  • Formulas apply from roughly 1–12 years; use length- or weight-based tools (e.g. Broselow) in infants and neonates.

References

  1. Cole F. AMA Am J Dis Child. 1957;94(6):672-3.
  2. Khine HH, Corddry DH, Kettrick RG, et al. Anesthesiology. 1997;86(3):627-31.