QTc Calculator

The QT interval on an ECG shortens as the heart speeds up, so it has to be corrected to a rate of 60 beats a minute before it can be compared with anything. Enter the measured QT along with either the heart rate or the RR interval, and it returns the Bazett, Fridericia, Framingham and Hodges corrections side by side, with the sex-specific cut points applied to the Bazett figure. An optional QRS duration flags the case where a wide QRS inflates every correction, and the result says when the rate is outside the range where Bazett can be trusted. The arithmetic is only as good as the QT it is given, and reading that interval off the trace is the clinician's job, not this page's.

Calculator Type
The measured, uncorrected QT in milliseconds, as read from the trace or printed by the machine.
The rate for the same beats the QT was measured on. In an irregular rhythm an average over several beats is the usual compromise.
The published cut points for a prolonged QTc differ by about 20 ms between men and women.
Leave blank if you are not measuring it. A QRS of 120 ms or more makes every QTc formula read long.
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The measured, uncorrected QT in milliseconds, as read from the trace or printed by the machine.
R wave to R wave in milliseconds. At 25 mm per second each large square is 200 ms, so five large squares is 1000 ms.
The published cut points for a prolonged QTc differ by about 20 ms between men and women.
Leave blank if you are not measuring it. A QRS of 120 ms or more makes every QTc formula read long.
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