On an ECG, how is heart rate calculated using large boxes?

The calculation of heart rate using large boxes on an ECG is based on the number of large boxes between two successive R waves, which represent one cycle of the heartbeat. The method used is straightforward: you divide 300 by the number of large boxes. This formula stems from the fact that there are 300 large boxes in a standard 6-second strip of an ECG, and thus, it allows for a quick assessment of the heart rate.

For example, if the distance between two R waves is 3 large boxes, the heart rate would be calculated as 300 divided by 3, resulting in a heart rate of 100 beats per minute. This method is widely used by healthcare professionals to assess heart rates efficiently and accurately during an ECG reading. The reliance on this specific formula makes it a vital tool in clinical practice for monitoring cardiac function.