What does each large square represent when measuring the height of peaks in an EKG?

In an EKG, each large square on the graph represents a measurement of 5 millimeters by 5 millimeters. This dimension is crucial for assessing the amplitude of the electrical signals recorded during the heartbeat. The vertical axis of the EKG represents voltage (or height of the peaks), and to determine the height in millimeters, you simply count the number of large squares that the peak spans.

Since each large square equals 5 millimeters vertically, if a peak reaches up to one large square, it is interpreted as having a height of 5 millimeters. Therefore, this standard measurement allows healthcare professionals to accurately assess the amplitude and determine if it falls within normal limits or indicates a potential anomaly, such as hypertrophy, ischemia, or other cardiac conditions. Understanding this measurement is essential for correct interpretation of EKG readings.