Corrected QT (Framingham) Calculator

About this calculator

The Framingham correction is a linear formula for adjusting the QT interval on an ECG for the patient's heart rate: QTc = QT + 0.154 × (1000 − RR), where RR is the interval between heartbeats in milliseconds. It was derived by linear regression from the Framingham Heart Study population and is one of several competing QT-correction methods alongside Bazett's square-root formula (the oldest and most widely used, but known to overcorrect at fast heart rates) and Fridericia's cube-root formula.

Cardiologists, ECG-interpretation software, and clinical researchers use a rate-corrected QT because the raw QT interval shortens and lengthens with heart rate on its own, which would otherwise make a fast heart rate look falsely reassuring and a slow one look falsely prolonged. QTc values matter clinically because a markedly prolonged QT interval is associated with a higher risk of the dangerous ventricular arrhythmia torsades de pointes, so QTc is routinely checked when starting medications known to prolong the QT interval and in the workup of congenital long-QT syndromes.

This calculator takes a measured QT interval and heart rate and applies the Framingham linear formula to return the corrected QTc value.