Endotracheal tube by gestational age
Endotracheal tube choice and insertion depth in the newborn depend on gestational age and weight. This calculator uses the gestational-age table adopted by neonatal resuscitation programs and returns the internal diameter, the depth at the upper lip mark, the straight blade and the matching suction catheter.
Enter the gestational age at birth. The calculator shows the tube insertion depth at the upper lip mark, the internal diameter of the tube, the straight blade number and the suction catheter size.
Values estimated from gestational age; weight also matters. Confirm the position by auscultation and radiograph (tip between T1 and T2). Alternative rule for depth: weight in kg + 6 cm.
Clinical decision-support tool for use by healthcare professionals. It does not replace clinical judgment or your unit's protocols.
Table by gestational age
23 to 24 weeks: 2.5 mm tube, 5.5 cm at the lip. 25 to 26: 2.5 mm, 6 cm. 27 to 29: 2.5 to 3 mm, 6.5 cm. 30 to 32: 3 mm, 7 cm. 33 to 34: 3.5 mm, 7.5 cm. 35 to 37: 3.5 mm, 8 cm. 38 to 40: 3.5 mm, 8.5 cm. From 41 weeks: 3.5 to 4 mm, 9 cm. Straight blade 00 in the smallest, 0 in most and 1 in the largest; suction catheter 6 to 8 F.
Position check
The tube tip should lie between T1 and T2, above the carina. Confirm by symmetric auscultation, chest rise, CO2 detector and radiograph. The alternative rule weight in kg + 6 cm gives a quick depth estimate when gestational age is uncertain.
Example
Newborn at 31 weeks: 3 mm internal diameter tube, inserted to the 7 cm mark at the upper lip, with a number 0 straight blade and a 6 to 8 F suction catheter. If the weight is 1.4 kg, the alternative rule gives 1.4 + 6 = 7.4 cm, close to the table value.
Frequently asked questions
Does the table apply to nasal intubation?
No. The depth values are for orotracheal intubation, measured at the upper lip mark. For the nasal route the depth is greater, usually 1 to 2 cm more.
Cuffed tube in a newborn?
Usual neonatal practice is an uncuffed tube. The diameters in the table refer to uncuffed tubes.
What if weight and gestational age disagree?
Weight is the best single guide for diameter. In a growth-restricted newborn, consider the tube indicated for the weight and confirm the depth radiographically.
References
- Brazilian Society of Pediatrics (SBP). Neonatal Resuscitation Program. Resuscitation of the newborn ≥ 34 weeks in the delivery room: 2026 guidelines.
- American Academy of Pediatrics; American Heart Association. Textbook of Neonatal Resuscitation (NRP). 8th ed. 2021.
- Kempley ST, Moreiras JW, Petrone FL. Endotracheal tube length for neonatal intubation. Resuscitation. 2008;77(3):369-73.
