This page covers how to calculate the QT interval on electrocardiograms (EKGs/ECGs).
QT interval: time between the start of the QRS complex and the end of the T wave (time between ventricular contraction and ventricular re-polarization). First calculate the time between the two subsequent R-R points (time between 2 ventricular contractions) and then make sure the QT interval is less than half this amount of time. Greater than half the RR interval is referred to as a prolonged QT.
Page Updated: 03.05.2018