How long is each small square in an EKG?

Each small square on an EKG represents a time interval of 0.04 seconds. This is a fundamental aspect of interpreting EKGs, as understanding the timing of the electrical activities of the heart is crucial for accurate diagnosis.

The EKG graph paper is divided into a grid, where each small square is 1 millimeter (mm) wide and tall. Since the standard speed for EKG recordings is 25 millimeters per second, when you divide that by the 25 squares that fit into that second, you find that there is a consistent measurement: each square thus corresponds to 0.04 seconds.

This measurement allows healthcare professionals to analyze the duration of various components of the cardiac cycle such as atrial and ventricular depolarization and repolarization. Recognizing this interval helps in understanding whether the heart's electrical signals are occurring within a normal time frame or if there are delays or abnormalities that need to be addressed.