Paediatric Intubation Tube Sizes

Disclaimer:  I have checked the formulas below, but cannot guarantee the below is up to date, or error free - please consult official sources for actual patient care! 
 
ET Intubation  


Uncuffed tubes

• Age > 1 year  
• Internal diameter (mm) = (Age/4) + 4 
• Length (cm) = (Age/2) + 12 (oral tube)
• Length (cm) = (Age/2) + 15 (nasal tube)
• Neonates
• Usually require tube internal diameter 3-3.5mm
• pre-term infants may need one of diameter 2.5 mm
• Rules of thumb
• ET tube internal diameter = gestational age/10 
• ET Tube length = 6 + weight
• not accurate if weight < 1 kilo

Cuffed tubes

• From 2 years 
• Internal diameter (mm) = (age/4) +3.5
• infants of more than 3 kg and up to one year a size 3.0 cuffed tube usually acceptable
• 1-2 years a size 3.5 cuffed tube are usually acceptable.

Source [APLS 4th ed, advice]