📈 ECG Heart Rate Calculator
Calculate heart rate from an ECG strip using the R-R interval, either in milliseconds or as a count of large ECG grid squares between two R waves.
How ECG heart rate is measured
On a standard ECG recorded at 25 mm/s, each large grid square represents 0.2 seconds (200 ms), and each small square represents 0.04 seconds (40 ms). Heart rate can be found from the interval between two consecutive R waves (the R-R interval).
How this calculator works
Choose whether you’re entering the R-R interval directly in milliseconds, or counting the number of large squares between two R waves on the strip. The calculator applies the standard formulas: Heart Rate (bpm) = 60,000 / R-R interval (ms), which is equivalent to 300 / number of large squares.
This tool is for general educational purposes only and does not replace interpretation by a qualified healthcare professional. ECG interpretation involves much more than rate alone; always consult a clinician for diagnostic evaluation.