ET Tube Size & Depth
Neonatal intubation is time-critical and unforgiving of error: an oversized tube injures the airway, an undersized one leaks, and a tube placed too deep enters the right main bronchus. This calculator gives the endotracheal tube internal diameter and a starting insertion depth from the NRP 9th edition (2025) tables, by gestational age, weight, or nasal-tragus length.
Nasal septum base → ear tragus
Enter a birth weight and/or gestational age to estimate tube size and depth.
Tube size (NRP 9th ed.)
| Weight | GA | ID |
|---|---|---|
| <800 g | 22–25 wk | 2.5* |
| 800–1200 g | 26–28 wk | 2.5 |
| 1201–2200 g | 29–34 wk | 3.0 |
| >2200 g | >34 wk | 3.5 |
*2.0 mm ID optional if available
Depth at gum (NRP 9th ed.)
| GA | Depth | Weight |
|---|---|---|
| <23 | 5.0–5.5 | <500 g |
| 23–24 | 5.5 | 500–600 |
| 25–26 | 6.0 | 700–800 |
| 27–29 | 6.5 | 900–1000 |
| 30–32 | 7.0 | 1100–1400 |
| 33–34 | 7.5 | 1500–1800 |
| 35–37 | 8.0 | 1900–2400 |
| 38–40 | 8.5 | 2500–3100 |
| 41–43 | 9.0 | 3200–4200 |
Weiner GM, ed. Textbook of Neonatal Resuscitation, 9th ed. American Academy of Pediatrics & American Heart Association; 2025 (Lesson 5: Endotracheal Intubation).
Kempley ST, Moreiras JW, Petrone FL. Endotracheal tube length for neonatal intubation. Resuscitation. 2008;77(3):369-373.
Frequently asked questions
How is ET tube depth estimated?
Weight-based (about weight in kg + 6 cm at the lip) or nasal–tragus length + 1 cm; the NRP 9th edition also provides gestational-age and weight tables. Confirm by exam and chest radiograph.
What ET tube size for a preterm infant?
Approximately 2.5 mm for under 1000 g/28 weeks, 3.0 mm for 1000–2000 g/28–34 weeks, and 3.5 mm above 2000 g/34 weeks.
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