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QTc Interval Calculator

This QTc Interval Calculator helps estimate the corrected QT interval (QTc) from the measured QT interval and heart rate (HR). It is commonly used in cardiology to assess risk for arrhythmias like Torsades de Pointes. By inputting QT duration and heart rate, the tool applies Bazett’s formula to provide the QTc value.

QT Corrected Interval

Input Fields
qt
value
If enabled, the result will update automatically when you change any value.

Bazett’s Formula for QT Correction

Formula
$$QT_c = \frac{QT_m}{\sqrt{RR}}, \quad \text{where} \quad RR = \frac{60}{HR}$$

Explanation:

  • $$QTₘ$$: measured QT interval (in seconds)
  • $$HR$$: heart rate (beats per minute)
  • $$RR$$: RR interval (the time between heartbeats in seconds)

Bazett’s formula is widely used but may overcorrect at high heart rates and undercorrect at low ones..


QTc (corrected QT interval) is essential in evaluating a patient’s risk for ventricular arrhythmias. A prolonged QTc can be drug-induced or genetic. This calculator uses Bazett’s formula, which is simple and widely adopted in clinical practice. Input the QT duration in milliseconds or seconds and the heart rate in bpm to receive the QTc value. It is especially important in cases where ECG abnormalities or syncope are present.

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