Airway & Oxygen

Pediatric ET Tube Size and Depth Calculator

Estimates endotracheal tube size and insertion depth from age.

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

Turn on JavaScript to use this calculator, or open it in the web app.

Formula

Uncuffed size = (age ÷ 4) + 4
Cuffed size = (age ÷ 4) + 3.5
Depth at the lip (cm) = 3 × uncuffed size

How it is used

• Cuffed tubes are acceptable at all ages beyond the newborn period; keep the cuff pressure under 20 to 25 cm H₂O.
• Confirm placement with waveform capnography, then breath sounds and chest rise; recheck after every move.

Same formula as the app. Open it in the web app.

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For education and exam preparation only. Follow your institution’s protocols. For education and exam preparation only. Verify results independently and follow your local protocols and medical direction. Not a substitute for clinical judgment.