# Corrected QT (QTc) Calculator (Bazett/Fridericia/Framingham) Calculate the heart-rate–corrected QT interval (QTc) with three formulae. Bazett (1920): QTc = QT/√RR (classic; over-corrects at high HR, under-corrects at low HR). Fridericia (1920): QTc = QT/RR^(1/3) — more accurate across a wide HR range, preferred for drug/QT studies. Framingham (1992): QTc = QT + 0.154×(1 − RR) — simple linear regression. RR is derived from heart rate (RR = 60/HR) when not provided; QT and QTc in ms. Thresholds: men > 450 ms borderline / > 480 ms prolonged; women > 460 ms borderline / > 480 ms prolonged; > 500 ms markedly prolonged. Derived from Bazett 1920, Fridericia 1920, Sagie/Framingham 1992, AHA 2009, ICH E14, and MDCalc. Not medical advice. > Canonical page: https://elysiatools.com/en/tools/corrected-qt-bazett-fridericia - **Category:** Health - **Keywords:** corrected QT, QTc, Bazett, Fridericia, Framingham, QT prolongation, torsades de pointes, long QT syndrome, LQTS, ECG, electrocardiogram, cardiology, antiarrhythmic, ICH E14 ## Overview Calculate the heart-rate-corrected QT interval (QTc) in milliseconds using the Bazett, Fridericia, or Framingham formula. Enter a measured QT interval and heart rate, or provide an RR interval directly; the result includes the QTc value, RR interval, selected method, and category. This calculator is not medical advice. ## Inputs - **Formula** (select) - **Sex** (select) - **QT interval (ms)** (number): Measured QT interval in milliseconds (longest of 3 consecutive beats, lead V5 or II preferred). - **Heart rate (bpm)** (number): Heart rate in bpm. Used to derive RR when RR is not given (RR = 60/HR). - **RR interval (s, optional)** (number): Optional RR interval in seconds. Overrides the HR-derived RR when provided. - **Decimal Places** (number) ## When to use - Estimate QTc from an ECG-measured QT interval and heart rate. - Compare Bazett, Fridericia, and Framingham correction methods. - Review QTc values against sex-specific reference thresholds during ECG or medication assessment. ## How it works - Select the correction formula and sex, then enter the QT interval in milliseconds. - Enter heart rate in bpm to derive RR as 60 divided by heart rate, or provide an RR interval in seconds. - If both are provided, the supplied RR interval overrides the heart-rate-derived value. - The calculator returns QTc in milliseconds, the selected formula, RR interval, and a QTc category. ## Use cases - ECG review using a measured QT interval and heart rate. - Cardiology and clinical research comparisons of QTc correction formulas. - Medication or risk assessment where QT prolongation requires further clinical review. ## Frequently asked questions ### What inputs are required? You must select a formula and sex and enter the measured QT interval in milliseconds. Heart rate or RR interval is also needed to calculate QTc. ### Can I enter an RR interval instead of heart rate? Yes. Enter RR in seconds. When provided, it overrides the RR derived from heart rate. ### Which QTc formulas are available? The calculator supports Bazett, Fridericia, and Framingham correction formulas. ### What do the QTc categories mean? For men, values above 450 ms are borderline and above 480 ms are prolonged. For women, values above 460 ms are borderline and above 480 ms are prolonged; values above 500 ms are markedly prolonged. ### Is this calculator medical advice? 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