How to Calculate the Heart Rate from Ecg

ECG Heart Rate Calculator (1500-Rule)

Use this calculator to determine a patient's heart rate from an Electrocardiogram (ECG) strip using the 1500-rule. This method is most accurate for regular heart rhythms.

Enter the count of small squares between two consecutive R-waves on the ECG strip.

function calculateHeartRate() { var smallSquaresInput = document.getElementById("smallSquares").value; var smallSquares = parseFloat(smallSquaresInput); var resultDiv = document.getElementById("result"); if (isNaN(smallSquares) || smallSquares <= 0) { resultDiv.innerHTML = "Please enter a valid number of small squares (greater than 0)."; return; } var heartRate = 1500 / smallSquares; resultDiv.innerHTML = heartRate.toFixed(2) + " BPM (Beats Per Minute)"; }

Understanding Heart Rate Calculation from ECG

An Electrocardiogram (ECG or EKG) is a simple, non-invasive test that records the electrical activity of the heart. It's a fundamental tool in cardiology for diagnosing various heart conditions. One of the most basic yet crucial pieces of information derived from an ECG is the heart rate.

The ECG Grid Explained

ECG paper is a grid of small and large squares. Typically:

• Each small square represents 0.04 seconds horizontally (time) and 0.1 mV vertically (amplitude).
• Five small squares make up one large square. Therefore, each large square represents 0.20 seconds (5 x 0.04s).
• Five large squares represent 1 second (5 x 0.20s).

The standard paper speed for an ECG is 25 mm/second, meaning 25 small squares pass per second.

Methods for Calculating Heart Rate

There are several methods to calculate heart rate from an ECG, depending on whether the rhythm is regular or irregular.

1. The 1500-Rule (for Regular Rhythms)

This is the most precise method for calculating heart rate when the rhythm is regular. It's based on the fact that there are 1500 small squares in one minute (60 seconds / 0.04 seconds per small square = 1500 small squares).

How to use it:

1. Identify two consecutive R-waves (the tall, sharp peaks on the ECG).
2. Count the exact number of small squares between these two R-waves (this is the R-R interval in small squares).
3. Divide 1500 by this number.

Formula: Heart Rate (BPM) = 1500 / (Number of Small Squares between R-waves)

Example: If there are 25 small squares between two R-waves, the heart rate is 1500 / 25 = 60 BPM.

This calculator uses the 1500-rule to provide an accurate heart rate.

2. The 300-Rule (for Regular Rhythms)

A quicker, less precise method for regular rhythms, based on the fact that there are 300 large squares in one minute (60 seconds / 0.20 seconds per large square = 300 large squares).

How to use it:

1. Identify two consecutive R-waves.
2. Count the number of large squares between these two R-waves.
3. Divide 300 by this number.

Formula: Heart Rate (BPM) = 300 / (Number of Large Squares between R-waves)

Example: If there are 5 large squares between two R-waves, the heart rate is 300 / 5 = 60 BPM.

3. The 6-Second Rule (for Irregular Rhythms)

When the heart rhythm is irregular (e.g., Atrial Fibrillation), the R-R interval varies, making the 1500-rule or 300-rule unreliable. The 6-second rule is used in these cases.

How to use it:

1. Find a 6-second strip on the ECG. This corresponds to 30 large squares (6 seconds / 0.20 seconds per large square = 30 large squares).
2. Count the number of R-waves within that 6-second strip.
3. Multiply that number by 10 to get the heart rate in beats per minute.

Formula: Heart Rate (BPM) = (Number of R-waves in 6 seconds) x 10

Example: If you count 7 R-waves in a 6-second strip, the heart rate is 7 x 10 = 70 BPM.

Why is Heart Rate Important?

Monitoring heart rate is vital for assessing cardiovascular health. A normal resting heart rate for adults typically ranges from 60 to 100 beats per minute. Deviations from this range can indicate underlying health issues, such as:

• Bradycardia: A heart rate that is too slow (below 60 BPM).
• Tachycardia: A heart rate that is too fast (above 100 BPM).

Accurate heart rate calculation from an ECG helps healthcare professionals make informed decisions about patient care and treatment.