QTc Calculator
Corrected QT interval with the Bazett, Fridericia, Framingham and Hodges formulas.
Enter your values to see the result.
Bazett over-corrects at fast heart rates, so Fridericia or Framingham is preferred above about 90 bpm. Prolonged: above 450 ms (men) or 460 ms (women); above 500 ms carries a high risk of torsades de pointes. For education and clinical decision support only. Results do not replace professional judgment, local protocols or the product information, so always verify doses and values before acting on them.
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How to use the QTc Calculator
Corrected QT interval with the Bazett, Fridericia, Framingham and Hodges formulas.
- 1 Enter the measured QT interval in milliseconds.
- 2 Enter the heart rate or the RR interval, and sex.
- 3 Read the QTc from every formula and whether it is prolonged.
Example and practical tips
A QT of 400 ms at 75 bpm gives a Bazett QTc of 447 ms, just under the 450 ms limit for men.
Frequently asked questions
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.
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