Which formula does this calculator use?

For uncuffed tubes: ID (mm) = (age/4) + 4 (Motoyama). For cuffed tubes: ID (mm) = (age/4) + 3.5 (Khine). Below age 1, neonatal weight-based sizing is applied. These are starting estimates — always have sizes ± 0.5 mm available.

When should I use a cuffed versus uncuffed ETT?

Cuffed tubes are now widely accepted in children over 1 year for better seal control and reduced reintubation rates. Uncuffed tubes are still preferred in neonates. Either may be appropriate depending on institutional protocol and clinical scenario.

How do I estimate insertion depth?

The 3× ID rule (depth at lip = 3 × tube ID in mm) is a common bedside estimate. An age-based alternative is (age/2) + 12 cm for oral intubation. Confirm with a chest X-ray and bilateral breath sounds.

What cuff pressure should I target?

Inflate to 20–25 cmH2O (or the minimum occlusive pressure). Pressures above 30 cmH2O risk mucosal ischemia. Use a manometer — do not rely on pilot-balloon feel.

Is this tool appropriate for premature neonates?

Extreme prematurity requires weight-based sizing that accounts for gestational age, which is beyond a simple age/weight formula. Use institutional NICU reference cards for infants below 1 kg.

Does this replace clinical judgment?

No. This is a reference aid only. Airway decisions must be made by a qualified clinician with full awareness of the patient's anatomy, clinical status, and available equipment.

Pediatric ETT Size Calculator

Name: Pediatric ETT Size Calculator
Availability: InStock
Author: Nham Vu

Enter patient age and weight to get the recommended ETT internal diameter, cuffed/uncuffed options, insertion depth at lips, and cuff pressure guidance.

Patient Parameters

Enter age and weight to generate ETT recommendations.

Age (years — use decimals for months, e.g. 0.5 = 6 mo)

Weight (kg — optional, used for neonate sizing)

Tube preference

Show both Uncuffed only Cuffed only

Formula Reference

Tube type	Formula (ID mm)
Uncuffed (>1 yr)	(age/4) + 4
Cuffed (>1 yr)	(age/4) + 3.5
Depth at lip	3 × ID (mm) cm
Depth (age-based)	(age/2) + 12 cm
Cuff pressure	20–25 cmH2O

Enter patient age and weight, then click Calculate ETT Size.

Recommended ETT

Uncuffed

Smaller

mm ID

Primary

mm ID

Larger

mm ID

Cuffed

Smaller

mm ID

Primary

mm ID

Larger

mm ID

Depth & Cuff Pressure

Depth at lip (3× ID)

Depth at lip (age-based)

Cuff pressure target

20–25

cmH2O

Clinical Notes

Clinical reference only. ETT sizes are estimates based on population formulas. Always have one size above and below available. Confirm placement with waveform capnography, bilateral breath sounds, and chest X-ray. Decisions must be made by a qualified clinician.

Summary

Enter patient age and weight to get the recommended ETT internal diameter, cuffed/uncuffed options, insertion depth at lips, and cuff pressure guidance.

How it works

Enter the patient's age in years (use decimals for months, e.g. 0.5 for 6 months) and weight in kg.
The calculator applies standard age-based formulas to derive the recommended uncuffed ETT internal diameter (ID).
A cuffed tube recommendation is also shown (typically 0.5 mm smaller than the uncuffed equivalent).
Insertion depth at the lip is estimated using the 3× tube ID rule and an age-based alternative so you can cross-check.
Cuff pressure guidance (target 20–25 cmH2O) and a reminder to confirm placement with waveform capnography are displayed.
Review adjacent sizes — one above and one below — before preparing your equipment.

Use cases

Rapid equipment sizing during pediatric resuscitation.
Anesthesia pre-op planning for pediatric surgical patients.
PICU and NICU airway management reference.
Paramedic and transport-team preparation for pediatric airways.
Medical student and resident education on ETT sizing formulas.
Simulation and training scenarios for pediatric airway skills.

Frequently Asked Questions

Last updated: 2026-07-24 · Reviewed by Nham Vu