About ECG paper

ECG graphs are presented on standard ECG paper. ECG paper speed is usually 25 mm/second.

If you zoom in on a graph, you can see that the paper is divided into small boxes. Each box represents a 1 mm interval or 0.04 seconds (40 ms).

 

A group of 5 horizontal boxes, bordered by a thick line, represents a 5 mm interval or 0.2 seconds (200 ms).

 

A group of 25 boxes, bordered by a thick line, represents a 25 mm interval or 1 second.