Measure the QT interval from the start of the Q wave to the end of the T wave
Measure the RR interval between two consecutive R waves
Use Bazett’s formula: QTc = QT / √RR
Use QT in seconds and RR in seconds
Convert the result to milliseconds if needed
Alternative formulas:
Fridericia: QTc = QT / ∛RR
Framingham: QTc = QT + 0.154 × (1 − RR)
Hodges: QTc = QT + 1.75 × (heart rate − 60)
Compare the QTc value with standard reference ranges