The QT interval represents the time of ventricular depolarization and repolarization on the ECG. Because it depends on heart rate, a corrected QT (QTc) is commonly used. This calculator estimates QTc using Bazett’s formula (QTc = QT / √RR) for educational purposes only and is not meant to guide individual treatment decisions.
Corrected QT Interval (QTc) Calculator
Enter the measured QT in milliseconds and the heart rate in beats per minute.
Results
RR interval: – ms (– s)
QTc (Bazett): – ms
Approximate reference values (adults): QTc < 440 ms in men and < 460 ms in women is often considered normal, whereas persistent QTc ≥ 480–500 ms is associated with a higher risk of arrhythmias. Interpretation must always be made by a qualified healthcare professional.
References
-
Life in the Fast Lane (LITFL).
QT Interval – ECG Library Basics. Available at:
QT Interval
- ACEP Toxicology Section. QTc: So many formulae, but which one to use? 2021. Available at: https://www.acep.org/...
- Johnson JN, Ackerman MJ. QTc: how long is too long? Curr Opin Cardiol. 2009.
- Daviés RA et al. The 2023 Canadian Cardiovascular Society Clinical Practice Update on QTc interpretation.