Resuscitation and airway
Endotracheal tube size and depth
Tube size (cuffed and uncuffed) and insertion depth for children aged 1 year and over.
For education. Check against your unit's guidance and a second clinician before use.
For children aged 1 year and over. See the table below for babies.
years
Fill in the boxes above to see the result.
Before you use this
- These are starting points. Confirm placement with capnography, chest movement, auscultation and a chest X-ray.
- Many units now use cuffed tubes for most children. Check the cuff pressure.
Babies under 1 year (commonly quoted starting sizes)
| Age | Uncuffed | Cuffed |
|---|---|---|
| Term newborn | 3.0–3.5 mm | 3.0 mm |
| Under 1 year | 3.5–4.0 mm | 3.0–3.5 mm |
How this is calculated
- Cuffed tube internal diameter (mm) = (age in years ÷ 4) + 3.5
- Uncuffed tube internal diameter (mm) = (age in years ÷ 4) + 4
- Oral length (cm) = (age in years ÷ 2) + 12
- Nasal length (cm) = (age in years ÷ 2) + 15
- Sizes are rounded to the nearest half millimetre.
Sources
- Advanced Life Support Group. Advanced Paediatric Life Support (APLS), 6th edition. Wiley-Blackwell, 2016.
- Resuscitation Council UK. Paediatric advanced life support guidelines (current edition).
Checked by PICUlearn, 21 Sept 2026.