The duration of the P wave in these three patients ranges from 88 to 120 ms. P wave duration is usually best measured in lead II and in which ever other lead, or leads, permit the most accurate assessment of the beginning and end of the P wave. In the example shown here, the onset and offset of the P wave is well seen in lead aVF as well as lead II. The normal P wave duration on the body surface ECG in adults ranges from 70 to 120 ms.