. The optimal position of the endotracheal tube (ETT) within the trachea is the middle third portion, distal to the vocal cords. In addition to clinical assessments, methods such as posteroanterior chest radiography (PA-CXR) and fiberoptic bronchoscopy (FOB) can be used to verify ETT placement.

In our study, we aim to explain the relationship between the most accurate endotracheal tube depth and various formulas by using fiberoptic bronchoscopy, with the help of four different formulas based on age, height, weight, and third finger length.The study further seeks to:

1. To identify the most accurate formula for estimating ETT placement depth in the pediatric population living in Turkey.
2. To reduce the potential complications that may arise from incorrect ETT depth.
3. To determine which formula, when verified by fiberoptic bronchoscopy, is also consistent with auscultation findings-especially in situations where chest radiography or fiberoptic bronchoscopy may not be readily available.

Inclusion Criteria:

• American Society of Anesthesiologists (ASA) physical status 1 , 2 or 3
• Patients scheduled for elective surgical procedures
• Informed consent must be obtained from both the patient and, if applicable, their parent or guardian.

Exclusion Criteria:

• Patients under 1 year old or over 4 years old
• Patients with tracheobronchial anomalies
• Patients with vertebral column anomalies
• Patients with a history of tracheostomy and difficult intubation
• Patients who do not want to be included in the study
• Children with finger anomalies and syndromic associations
• Cases requiring nasal intubation

Between 1 and 4years of ages pediatric patients scheduled for elective surgery under general anesthesia