QT/QTc Calculator
Calculate Bazett, Fridericia, Framingham, and Hodges QTc and baseline changes from QT/RR.
QT/QTc results
Enter QT and RR intervals.
Methods can disagree; no clinical decision is made automatically. ICH E14 notes heart-rate-dependent bias with Bazett in adults and that Fridericia may suit many situations, but drugs affecting heart rate can require a prospectively specified population/individual correction and QT-RR independence assessment. Time-matched baseline, placebo adjustment, and replicate ECG analysis remain separate.
Basis: ICH E14 Bazett, Fridericia, and Framingham equations and QT-correction guidance.
Tool Guide
Definition
QT/QTc Calculator — Calculates Bazett, Fridericia, Framingham, and Hodges population corrections in parallel from QT and RR intervals in milliseconds. Optional baseline QT/RR is corrected by the same formulas to obtain ΔQTc.
Purpose
(1) Cross-check ECG QT/RR calculations (2) Compare QTc results across correction methods (3) Calculate baseline ΔQTc using the same correction (4) Prepare a helper table for inspecting Bazett bias during heart-rate changes
How to Use
① Enter current QT and its matched beat/aggregate RR interval in milliseconds. ② For change from baseline, enter prospectively defined baseline QT and RR together. ③ Copy current QTc and ΔQTc for each formula. ④ Separately inspect QTc-RR plots, heart-rate effects, and the rationale for the chosen correction. Placebo-adjusted ΔΔQTc, replicate-ECG aggregation, concentration-QTc modeling, and clinical decisions are excluded.
Examples
Example) QT=400 ms and RR=500 ms (HR=120 bpm) → QTcB=565.69 ms, QTcF=503.97 ms, QTcFramingham=477 ms, QTcHodges=505 ms The example shows stronger Bazett correction at a high heart rate. The numbers are not classified automatically.