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Calculate pediatric Endotracheal Tube Size with cuffed, uncuffed, and ETT length formulas. Get fast, simple, and accurate ETT size estimates online.
| Infant Category | Typical ETT Size |
|---|---|
| Very small premature infants | 2.5 mm |
| 1,000–2,000 g | 3.0 mm |
| 2,000–3,000 g | 3.5 mm |
Choosing the right Endotracheal Tube Size is important during airway management. A tube that is too small may cause a large air leak. A tube that is too large may increase airway injury risk. Pediatric tube size can be estimated from age, but the formula is only a guide.
Our Endotracheal Tube Size calculator makes this calculation simple. Enter the child's age, and the calculator estimates the cuffed and uncuffed tube size. It can also estimate endotracheal tube length.
For children older than 2 years, a common formula for an uncuffed ETT is:
Uncuffed ETT size = (Age ÷ 4) + 4 mm
For a cuffed ETT, a commonly used formula is:
Cuffed ETT size = (Age ÷ 4) + 3.5 mm
These formulas estimate the tube's internal diameter (ID) in millimeters. The +3.5 cuffed formula is supported by pediatric airway literature.
For ETT length or insertion depth, a commonly used estimate after age 2 is:
ETT depth = (Age ÷ 2) + 12 cm
Another useful estimate is:
ETT depth = ETT internal diameter × 3 cm
These depth formulas are estimates and should not replace clinical confirmation of tube position.
Uncuffed ETT (Age ÷ 4) + 4 mm
Cuffed ETT (Age ÷ 4) + 3.5 mm
Age-based ETT depth (Age ÷ 2) + 12 cm
Size-based ETT depth ETT ID × 3 cm
Suppose a child is 6 years old.
First, calculate the uncuffed tube:
(6 ÷ 4) + 4 = 5.5 mm
So, the estimated uncuffed endotracheal tube size is 5.5 mm ID.
Now calculate the cuffed tube:
(6 ÷ 4) + 3.5 = 5.0 mm
So, the estimated cuffed endotracheal tube size is 5.0 mm ID.
Now calculate the age-based tube depth:
(6 ÷ 2) + 12 = 15 cm
So, the estimated oral ETT depth is 15 cm.
Adult ETT sizing isn't normally calculated with the pediatric age formula. Adult tube choice depends on factors such as the patient's airway, sex, clinical situation, and the purpose of ventilation.
Many adults can accept an ETT with an internal diameter of 8 mm or larger, although smaller tubes may be selected when clinically appropriate.
Therefore, the pediatric endotracheal tube size calculation in this calculator shouldn't be applied to adult patients.
An endotracheal tube is used to secure the airway through the mouth or nose. A tracheostomy tube is placed through a surgical opening in the neck.
Because they differ in design and use, a tracheostomy tube size calculator shouldn't use the same formula as a pediatric ETT calculator. Tracheostomy tube selection requires different clinical measurements and manufacturer-specific sizing.
The Endotracheal Tube Size calculator gives a fast estimate of pediatric ETT size. The main formulas are (Age ÷ 4) + 4 for an uncuffed tube and (Age ÷ 4) + 3.5 for a cuffed tube. ETT depth can also be estimated with (Age ÷ 2) + 12 or ETT ID × 3.
These formulas are estimates, not guarantees. Actual tube selection and placement should be confirmed by a qualified clinician. Tube position should be clinically assessed and confirmed with appropriate monitoring, including exhaled CO₂ when available.
For an uncuffed tube, use (Age ÷ 4) + 4 mm. For a cuffed tube, use (Age ÷ 4) + 3.5 mm in appropriate older pediatric patients.
A commonly used pediatric estimate after age 2 is (Age ÷ 2) + 12 cm. Another estimate is ETT internal diameter × 3.
Yes. Pediatric ETT size is generally stated by its internal diameter (ID) in millimeters. The outer diameter can vary between tube designs and manufacturers.
No. Age-based formulas are estimates and can be inaccurate in individual children. Having a tube 0.5 mm smaller and larger available is recommended.
No. The age-based pediatric formula isn't an adult ETT size calculation method. Adult tube selection requires clinical assessment.
ETT sizing concerns a tube placed through the mouth or nose into the trachea. Tracheostomy tube sizing concerns a tube placed through a surgical airway. Their sizing methods are different.