QTc Calculator (Comprehensive)

Advanced QTc calculation using Bazett, Fridericia, Framingham, and Hodges formulas, with Wide QRS adjustment.

Last updated on: April 16, 2026

Calculate QTc

ms

Clinical Significance

The QT interval on an ECG varies inversely with heart rate. The Corrected QT (QTc) estimates the QT interval at a standard heart rate of 60 bpm, allowing for the assessment of absolute repolarization prolongation.

A prolonged QTc is highly arrhythmogenic and is the primary risk factor for Torsades de Pointes (TdP).

Reference Ranges (Bazett)

Normal QTc: Male: ≤ 430 ms | Female: ≤ 450 ms. Normal repolarization, low risk of arrhythmias.
Borderline QTc: Male: 431 - 450 ms | Female: 451 - 470 ms. Monitor closely and use QT-prolonging drugs with caution.
Prolonged (Abnormal): Male: > 450 ms | Female: > 470 ms. High risk of Torsades de Pointes. Review medications and electrolytes.

Multi-Formula Approach

While Bazett is the most widely used, it overcorrects at high heart rates. Fridericia and Framingham are more accurate at extremes of heart rate. If QRS > 120ms is entered, Bogossian/Modified formulas are applied to adjust for wide complex durations.

This page has been medically reviewed by Dr. Khoulah Attia – PharmD, Immunology Specialist.

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