This version was machine-translated from German and has not been medically reviewed. The authoritative version is the German version.

QTc calculator

QT interval and heart rate → QTc according to Bazett, Fridericia, Hodges and Framingham, with pediatric reference values

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Sources

An analysis of the time-relations of electrocardiograms (Heart 7:353–370) Bazett HC, 1920. Original paper (reprint Ann Noninvasive Electrocardiol 1997)
The duration of systole in the electrocardiogram in normal persons and in heart patients (Acta Med Scand 53:469–486) Fridericia LS, 1920. Original paper
Bazett's QT correction reviewed: evidence that a linear QT correction for heart rate is better (J Am Coll Cardiol 1:694) Hodges M, Salerno D, Erlien D, 1983. Conference contribution (abstract)
An improved method for adjusting the QT interval for heart rate (the Framingham Heart Study) (Am J Cardiol 70:797–801) Sagie A, Larson MG, Goldberg RJ, Bengtson JR, Levy D, 1992. Original paper
Electrocardiograms in Healthy North American Children in the Digital Age (Circ Arrhythm Electrophysiol 11:e005808) – Table 2: QTc (Bazett, lead II) by age and sex Saarel EV, Granger S, Kaltman JR et al., Pediatric Heart Network, 2018. Reference-value study in 2,400 healthy children (19 centers), digital 12-lead ECGs
2022 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death (Eur Heart J 43:3997–4126) Zeppenfeld K, Tfelt-Hansen J, de Riva M et al., European Society of Cardiology, 2022. Guideline

Scientific basis last reviewed: September 2026.

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Note

Calculation aid for healthcare professionals. Percentiles and z-scores describe the position of a measured value in the reference population; clinical assessment remains with the treating physician.