This calculator helps you determine a patient's heart rate directly from an Electrocardiogram (ECG or EKG) tracing. Understanding how to calculate heart rate from an ECG is a fundamental skill for healthcare professionals, providing crucial information about cardiac rhythm and rate.
How it Works: ECGs record the electrical activity of the heart over time. The paper or digital display of an ECG has a grid where each small box typically represents 0.04 seconds and each large box (made up of 5 small boxes) represents 0.20 seconds. For a standard-rate ECG (25 mm/sec), the R-R interval (the distance between two consecutive R waves) is used to calculate the heart rate.
Inputs:
Result:
Heart Rate: — bpm
function calculateHeartRate() {
var rrIntervalInput = document.getElementById("rrInterval");
var heartRateOutput = document.getElementById("heartRateOutput");
var rrInterval = parseFloat(rrIntervalInput.value);
if (isNaN(rrInterval) || rrInterval <= 0) {
heartRateOutput.textContent = "Invalid input";
return;
}
// Standard ECG paper speed is 25 mm/sec.
// Each large box is 5 small boxes, so 5 * 0.04 sec = 0.20 sec.
// Heart rate = 60 seconds / (R-R interval in seconds)
// R-R interval in seconds = rrInterval (in large boxes) * 0.20 seconds/large box
// Heart rate = 60 / (rrInterval * 0.20)
// Heart rate = 300 / rrInterval
var heartRate = 300 / rrInterval;
heartRateOutput.textContent = heartRate.toFixed(0); // Display as whole bpm
}