QTc Calculator

Correct a raw QT interval for heart rate using the three standard formulas — the classic ECG safety check for medication and arrhythmia risk.

Measured QT interval

Milliseconds, usually from lead II or V5 on the ECG.

Heart rate

RR ms = 60,000 / bpm.

Sex (for reference range)

Formulas
Bazett: QTc = QT / √RR — standard, but distorts at extremes.
Fridericia: QTc = QT / RR^(1/3) — more stable at fast rates.
Framingham: QTc = QT + 0.154(1−RR) — linear regression method.

💔 Three formulas

Bazett, Fridericia, Framingham side-by-side.

⚖️ Rate input

Enter bpm or RR interval directly.

⚠️ Risk bands

Normal → borderline → prolonged → high.

📖 Drug safety

Common use: check meds that prolong QT.