Atrial Fibrillation ECG Heart Rate Calculator
Calculate ventricular rate for irregular rhythms using the 6-second or 10-second method.
6 Seconds (30 large boxes)
10 Seconds (Standard 12-lead duration)
3 Seconds (15 large boxes)
Estimated Heart Rate:
0 BPM
How to Calculate Heart Rate in Atrial Fibrillation
In a normal sinus rhythm, clinicians can use the 300-150-100 rule or the 1500 method because the R-R intervals are consistent. However, Atrial Fibrillation (AFib) is "irregularly irregular." This means the distance between heartbeats varies constantly, making traditional short-interval calculations inaccurate.
The 6-Second Rule (Gold Standard)
The most accurate way to calculate the heart rate during AFib on a paper ECG is the 6-second method:
- Identify a 6-second strip: On standard ECG paper (25mm/sec), 6 seconds equals 30 large squares. Many ECG papers have small vertical markers at the top indicating 3-second intervals.
- Count the R-peaks: Count the number of QRS complexes (the tall spikes) within that 30-square span.
- Multiply by 10: Since there are 10 six-second intervals in one minute (60 seconds), multiplying your count by 10 gives the average beats per minute (BPM).
Real-World Example
Imagine you have a 10-second standard 12-lead ECG printout. You count 14 QRS complexes across the entire bottom rhythm strip (Lead II). To find the heart rate:
- Calculation: 14 (complexes) × 6 (since 10s * 6 = 60s) = 84 BPM
AFib Heart Rate Reference Table (6-Second Method)
| QRS Complexes (in 6s) | Heart Rate (BPM) | Classification |
|---|---|---|
| < 6 | < 60 | Bradycardia |
| 6 – 10 | 60 – 100 | Controlled AFib |
| > 10 | > 100 | Rapid Ventricular Response (RVR) |