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Corrected QT: Bazett and Fridericia

Cardiovascular

Bazett over-corrects at fast heart rates and under-corrects at slow; Fridericia is preferred outside 60–100/min. Read the QT in lead II or V5.

What you enter

  • QT interval (ms)
  • Heart rate (/min)
  • Sex: Male / Female
FORMULABazett: QTc = QT ÷ √RR; Fridericia: QTc = QT ÷ ∛RR (RR in seconds = 60 ÷ HR)
SourceRautaharju PM et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the ECG, part IV: the QT interval. J Am Coll Cardiol 2009;53:982-91ReviewedFormula and thresholds checked against the source on 2026-08-22. If the source updates, this line will say so.