QTc methodsAwaiting inputs
—Four estimates will appear here.
Cardiology · ECG interpretation
QTc Comparison
Four common heart-rate correction methods displayed together. No formula is silently chosen for you.
Evidence recordSources and method currentVersion 0.1 · Updated July 17, 2026
Step 1
Enter ECG measurements
Private by design. Values are calculated on this device and are not saved or sent to analytics.
Step 2
Compare correction methods
No “safe” threshold is generated.Risk depends on context, including sex-related reference ranges, QRS duration, rhythm, medications, electrolytes, symptoms, and change from baseline.
Evidence packet
What this tool is based on
This versioned record keeps the citations, equation or decision rule, units, test coverage, intended population, and exclusions attached to the tool.
How evidence review works →Formula comparison · Validation studyLuo et al. A comparison of commonly used QT correction formulae.J Electrocardiol. 2004;37 Suppl:81–90. PMID: 15534815 ↗Outcome comparison · Validation studyVandenberk et al. Which QT correction formulae to use for QT monitoring?J Am Heart Assoc. 2016;5:e003264. PMID: 27317349 ↗Drug-effect methods · Validation studyIndik et al. Bazett and Fridericia corrections in assessment of drug-induced QT effects.Heart Rhythm. 2006;3(9):1003–1007. PMID: 16945790 ↗
Intended population
Patients with a measured QT interval and heart rate when comparison of common correction methods is clinically useful.
Equation record
Bazett, Fridericia, Framingham, and Hodges corrections displayed together; RR is derived as 60/heart rate.
Unit handling
QT accepts milliseconds and heart rate accepts beats/minute; RR is calculated in seconds and all QTc results return milliseconds.
Test coverage
Unity-RR reference case, all four equations, derived RR handling, and invalid inputs.
Do not skip
Limitations and exclusions
- Does not validate the QT measurement, ECG lead, rhythm, QRS duration, or tracing quality.
- Irregular rhythms, pacing, wide QRS, and bundle-branch block require specialized interpretation.
- No universal prolonged-QTc threshold or treatment decision is generated.
- Formula error increases at heart-rate extremes; Bazett commonly overcorrects at higher rates.
- Drug, electrolyte, symptom, sex-related reference, and baseline-change context remain essential.
One clearly labeled, contextually relevant sponsor may support this reference area. Sponsorship will never interrupt inputs, obscure results, influence formulas, or imply clinical endorsement.
About this tool
QTc Calculator – Bazett, Fridericia and More
Use this QTc calculator to compare Bazett, Fridericia, Framingham, and Hodges corrected QT estimates from the same QT interval and heart rate.
Each formula is displayed separately because correction methods can diverge, especially at heart-rate extremes. ECG quality, rhythm, measurement method, and clinical context still matter.