Calcmedical

Corrected QT (QTc)

CardiologyEmergency Medicine

Medical context

Correct the QT interval for heart rate using Bazett or Fridericia formulas.

Cardiology and medicine teams use this with ECG, biomarkers, and guideline-directed therapy context.

This page explains the QTc formula, how to interpret the output, known limitations, and peer-reviewed references so you can verify results against primary sources and local protocols.

It is grouped under Cardiology because stroke prevention, acs risk, and cardiac indices.

How to use this calculator

  1. Enter the values requested by the QTc calculator using the units shown beside each field.
  2. Review the calculated result and read the interpretation section before acting on the output.
  3. Check limitations and references if the result will change management, dosing, or disposition.
  4. Use the related calculators section when you need supporting values (for example electrolytes, weight, or complementary risk scores).

Calculator

Result

400 ms

Bazett

Educational use only. Confirm results with clinical judgment, primary sources, and local protocols. Not a substitute for professional medical advice. Full disclaimer.

Formula

Bazett: QTc = QT / √RR. Fridericia: QTc = QT / RR^(1/3), with RR in seconds.

Interpretation

Prolongation thresholds vary by sex and setting; ≥500 ms raises concern for arrhythmia risk.

Limitations

Bazett overcorrects at high HR; measurement technique and U waves matter.

Frequently asked questions

How do I get RR from heart rate?
RR (ms) ≈ 60,000 / heart rate (bpm).
Is the QTc result enough to make a treatment decision?
No. Calculators support medical decision-making but do not replace examination, shared decision-making, institutional protocols, or consultant input when stakes are high.
Does Calcmedical store the values I type in?
Inputs are processed in your browser for this session. We do not ask for patient names or medical record numbers. See our privacy policy for hosting and analytics details.

References

  • Bazett HC; Fridericia LS (historical formulas)
  • AHA/ACC QT measurement statements