ECG Heart Rate Calculator
How to Calculate Heart Rate on ECG Paper
Electrocardiogram (ECG) paper is a standardized grid used to measure the electrical activity of the heart. To calculate the Heart Rate (HR) manually, you must identify the R-waves (the sharp peaks) and measure the distance between them (the R-R interval).
• 1 Small Square = 1mm (0.04 seconds)
• 1 Large Square = 5mm (0.20 seconds)
• 5 Large Squares = 1 second
Common Calculation Methods
1. The 1500 Rule (Small Square Method): This is the most accurate method for regular rhythms. Since there are 1,500 small squares in one minute (60 seconds / 0.04), you divide 1500 by the number of small squares between two R waves.
Example: If there are 20 small squares between R waves: 1500 / 20 = 75 BPM.
2. The 300 Rule (Large Square Method): Best for quick estimation. There are 300 large squares in one minute. Divide 300 by the number of large squares between R waves.
Example: If there are 4 large squares between R waves: 300 / 4 = 75 BPM.
3. The 6-Second Method: Essential for irregular rhythms like Atrial Fibrillation. Count the number of QRS complexes within a 6-second strip (30 large squares) and multiply that number by 10.
Understanding the Results
- Normal Heart Rate: 60 – 100 BPM
- Bradycardia: Less than 60 BPM
- Tachycardia: Greater than 100 BPM