EKG Interval Calculator
Analyze ECG/EKG intervals with corrected QT calculation (Bazett, Fridericia, Hodges) and interpretation of PR, QRS, and QT intervals.
Medical Disclaimer
This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about your health. Never disregard professional medical advice or delay seeking it because of results from this tool.
Inputs
Results
QTc (Bazett)
447 ms
How to Use This Calculator
- Enter heart rate (bpm), PR interval (ms), QRS duration (ms), and QT interval (ms).
- Review QTc by Bazett, Fridericia, and Hodges formulas, RR interval, and status flags.
- QTc > 500 ms by any formula is critically prolonged and requires urgent clinical review.
- PR > 200 ms = first-degree AV block; QRS > 120 ms = bundle branch block or aberrant conduction.
How the result changes with QT interval
| QT interval | QTc (Bazett) |
|---|---|
| 70 | 78 ms |
| 245 | 274 ms |
| 455 | 509 ms |
| 630 | 704 ms |
What each input means
- Heart rate
- Ventricular rate in beats per minute.
- PR interval
- PR interval duration. Normal 120-200 ms.
- QRS duration
- QRS complex duration. Normal 60-100 ms.
- QT interval
- Measured QT interval (uncorrected).
What each result means
- QTc (Bazett)
- Bazett corrected QT = QT / √RR. Most widely used. Normal < 440 ms.
- QTc (Fridericia)
- Fridericia corrected QT = QT / RR^(1/3). More accurate at extreme heart rates.
- QTc (Hodges)
- Hodges linear correction = QT + 1.75 × (HR - 60).
- RR Interval
- Time between R waves. RR = 60000 / HR.
- PR Status
- 0 = Short (pre-excitation), 1 = Normal, 2 = First-degree AV block.
- QRS Status
- 0 = Normal, 1 = Incomplete BBB, 2 = Wide QRS / Complete BBB.
- QTc Status
- 0 = Normal, 1 = Borderline, 2 = Prolonged, 3 = Critically prolonged.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersHeart rate = 75, PR interval = 160, QRS duration = 90, QT interval = 400 = 4 input(s) provided
- Calculate QTc447 = 447
- Calculate QTc431 = 431
- Calculate QTcQTc = qtInterval + 1.75 * (heartRate - 60)426 = 426
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