Correct the QT interval for heart rate
Enter the measured QT and the heart rate or RR interval. Get the corrected QT by both Bazett and Fridericia.
Bazett divides QT by the square root of the RR interval in seconds. Fridericia divides QT by the cube root.
Corrected QT
- Bazett
- 447 ms
- Fridericia
- 431 ms
At a heart rate of 75 bpm the two corrections differ by 16 ms. They agree at 60 bpm and drift apart as the rate moves away from it.
How it works
Understand the result
Expect the QT to shorten as the heart rate rises
A correction estimates what the QT would be at 60 beats per minute, so you can compare ECGs taken at different rates.
Compare Bazett and Fridericia away from 60 bpm
Bazett overcorrects at fast rates and undercorrects at slow ones. Fridericia holds up better at both ends, so the calculator shows the two side by side.
Measure the QT with care
Atrial fibrillation, bundle branch block and a wide QRS make the measured QT less reliable. Machine readings can also misplace the end of the T wave.
Use the result to support your judgment
A calculator gives a number from the inputs you type. It knows nothing else about the patient, and it does not replace clinical judgment or local guidance.
In a workup
Bring the ECG report into the workspace
Upload the ECG report to the patient's workspace in Workup Desk. Ask the record for the QT and heart rate, then check the answer against the report it names.
See asking the recordQuestions
Frequently asked questions
Which formula should I report?
Many ECG machines report Bazett. Fridericia is often preferred at faster or slower rates. Say which one you used in the note.
Can I enter the RR interval instead of the rate?
Yes. Choose RR interval and enter it in milliseconds. The calculator also shows the heart rate it implies.