QTc Interval
Calculates corrected QT interval using Bazett, Fridericia, Hodges, and Framingham formulas
The QTc (corrected QT interval) adjusts the measured QT interval for heart rate, identifying children at risk of torsades de pointes and sudden cardiac death from acquired or congenital long QT syndrome. Using Bazett or Fridericia formulas, this calculator determines whether QT prolongation is present and whether it exceeds thresholds indicating increased arrhythmia risk. Apply this tool to all ECGs in children on QT-prolonging medications, with family history of sudden cardiac death, or with syncope to assess arrhythmia risk.
Clinically Verified· 5 testsFor educational and informational purposes only. Verify all results before clinical application.
Optional: provide heart rate OR RR interval. If both are provided, RR interval is used.
Optional: provide RR interval OR heart rate. RR (ms) = 60,000 / HR (bpm).
References
- Bazett HC. An analysis of the time-relations of electrocardiograms. Heart. 1920;7:353-370.
- Goldenberg I, Moss AJ, Zareba W. QT interval: how to measure it and what is "normal." J Cardiovasc Electrophysiol. 2006;17(3):333-336.[DOI]
Reviewed by Daniel Diaz-Gil, MD · Last updated March 2026
Medical disclaimer
This tool is for educational and informational purposes only. It is not a substitute for professional clinical judgment. Always independently verify results before making clinical decisions.