Calculators · Cardiology · Formula
Corrected QT interval (Bazett, Fridericia, Framingham, Hodges)
Also called QTc, QT correction, Bazett formula, Fridericia formula
Heart-rate corrected QT by the four common formulas side by side.
Fill 3 more fields to see the result.
Formula and scoring
RR (s) = 60/HR. Bazett QT/√RR; Fridericia QT/∛RR; Framingham QT + 154×(1 − RR); Hodges QT + 1.75×(HR − 60). QT in ms.
Exam and ward pearls
- Fridericia and Framingham gave the best rate correction and mortality prediction in 6,609 Leuven ECGs; Bazett performed worst.
- At HR 60 (RR 1 s) all four formulas return the measured QT.
When not to rely on it
- Measure QT in sinus rhythm with a normal QRS; corrections are unreliable in AF and with QRS widening.
- The 450/470 ms cut-offs are those used in the Leuven study; local drug-safety thresholds may differ.
Source
- Vandenberk B, Vandael E, Robyns T, et al. Which QT correction formulae to use for QT monitoring? J Am Heart Assoc. 2016;5(6):e003264. doi:10.1161/JAHA.116.003264 · PMID 27317349
- Sagie A, Larson MG, Goldberg RJ, Bengtson JR, Levy D. An improved method for adjusting the QT interval for heart rate (the Framingham Heart Study). Am J Cardiol. 1992;70(7):797-801. doi:10.1016/0002-9149(92)90562-d · PMID 1519533
Formula and cut-offs checked against these sources on 8 Nov 2026. Educational tool for clinicians; it does not replace clinical judgement.