📈 QTc Calculator (Bazett & Fridericia)
Calculate the heart-rate–corrected QT interval (QTc) using both Bazett and Fridericia formulas.
QTc Calculator (Bazett & Fridericia)
QT interval (ms)
Heart rate (bpm)
Sex
When to use
Screen for QT prolongation and torsades risk before or during QT-prolonging therapy.
How it works
Bazett QTc = QT/√RR; Fridericia QTc = QT/∛RR (RR in seconds = 60/HR). Prolonged: > 450 ms (men) / > 470 ms (women); > 500 ms high risk.
Key points
- Bazett over-corrects at fast and under-corrects at slow heart rates.
- Fridericia is preferred outside 60–100 bpm.
- Wide QRS inflates QT — interpret with care.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.