As a medical professional with expertise in cardiology, I can tell you that the PR interval on an ECG is a critical measurement that reflects the time it takes for electrical impulses to be transmitted from the atria to the ventricles of the heart. To determine the PR Interval, you measure the interval from the beginning of the P wave to the beginning of the QRS complex. Tools such as calipers, marked paper, or counting small boxes can be utilized for this purpose. Normal PR Interval: The normal range for the PR interval in adults is typically between 0.12 to 0.20 seconds, which corresponds to 3 to 5 small boxes on the ECG grid. It's important to note that the PR interval can be slightly longer in elderly individuals. read more >>

In this step you should measure the interval from where the P wave begins until the beginning of the QRS complex. Calipers, marked paper or counting small boxes methods can be used to determine PR Intervals. Normally this interval is 0.12 to 0.20 seconds (3 to 5 small boxes) in adults, longer in elderly people.read more >>