Irregular ECG Heart Rate Calculator
0 BPM
How to Calculate Heart Rate for Irregular Rhythms
In a normal, regular sinus rhythm, medical professionals often use the "300 Method" (counting large boxes between R-waves) or the "1500 Method" (counting small boxes). However, when a patient has an irregular rhythm like Atrial Fibrillation (AFib), these methods are inaccurate because the distance between R-waves changes constantly.
The gold standard for irregular ECG interpretation is the 6-Second Method. This provides a mean heart rate over a specific period of time.
The Formula:
(Number of R-waves / Number of Seconds in Strip) × 60 = Beats Per Minute (BPM)
(Number of R-waves / Number of Seconds in Strip) × 60 = Beats Per Minute (BPM)
Step-by-Step Guide
- Identify the Timeframe: On standard ECG paper moving at 25mm/sec, one large box is 0.2 seconds. To find a 6-second window, count 30 large boxes.
- Count the R-waves: Count every QRS complex (the tall spikes) that falls within those 30 large boxes.
- The Multiplication: If you used a 6-second strip, multiply the number of complexes by 10. If you used a 10-second strip, multiply by 6.
Realistic Examples
- Example 1 (6-second strip): You count 8 QRS complexes in a 6-second interval.
8 x 10 = 80 BPM (Average). - Example 2 (10-second strip): You count 15 QRS complexes in a 10-second interval.
15 x 6 = 90 BPM (Average).
This calculator automates the math for any strip length, ensuring you get an accurate average heart rate regardless of how irregular the rhythm appears on the paper.