Calculate the corrected QT interval with the Bazett, Fridericia, Framingham and Hodges formulas from QT and heart rate or RR, with prolongation flags.
About this tool
Corrected QT interval with the Bazett, Fridericia, Framingham and Hodges formulas.
How to use QTc Calculator
- Enter the measured QT interval in milliseconds.
- Enter the heart rate or the RR interval, and sex.
- Read the QTc from every formula and whether it is prolonged.
Worked example
A QT of 400 ms at 75 bpm gives a Bazett QTc of 447 ms, just under the 450 ms limit for men.
Which formula is best?
Bazett is the most familiar but overcorrects at fast heart rates. Fridericia or Framingham is more accurate outside 60–90 bpm.
When is QTc dangerous?
Above 500 ms, or a rise of more than 60 ms from baseline, the risk of torsades de pointes increases markedly.
- QTc Calculator — Corrected QT interval with the Bazett, Fridericia, Framingham and Hodges formulas.
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