How to Calculate Heart Rate Through Ecg

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ECG Heart Rate Calculator

Method 1: The Small Square Method (Most Accurate)

Method 2: The Large Square Method (Quick Estimate)

Method 3: The 6-Second Strip Method (For Irregular Rhythms)

Calculated Heart Rate: BPM

function updateInterpretation(bpm) { var interp = document.getElementById("interpretation"); if (bpm 100) { interp.innerText = "Interpretation: Tachycardia (Fast heart rate)"; interp.style.color = "#c0392b"; } else { interp.innerText = "Interpretation: Normal sinus rhythm range"; interp.style.color = "#27ae60"; } } function calculateBySmallSquares() { var val = document.getElementById("smallSquares").value; var resultDiv = document.getElementById("ecgResult"); var bpmSpan = document.getElementById("bpmValue"); if (val && val > 0) { var bpm = Math.round(1500 / val); bpmSpan.innerText = bpm; resultDiv.style.display = "block"; updateInterpretation(bpm); } else { alert("Please enter a valid number of small squares."); } } function calculateByLargeSquares() { var val = document.getElementById("largeSquares").value; var resultDiv = document.getElementById("ecgResult"); var bpmSpan = document.getElementById("bpmValue"); if (val && val > 0) { var bpm = Math.round(300 / val); bpmSpan.innerText = bpm; resultDiv.style.display = "block"; updateInterpretation(bpm); } else { alert("Please enter a valid number of large squares."); } } function calculateByStrip() { var val = document.getElementById("peakCount").value; var resultDiv = document.getElementById("ecgResult"); var bpmSpan = document.getElementById("bpmValue"); if (val && val > 0) { var bpm = val * 10; bpmSpan.innerText = bpm; resultDiv.style.display = "block"; updateInterpretation(bpm); } else { alert("Please enter the number of peaks found in the 6-second window."); } }

How to Calculate Heart Rate from an ECG Strip

Calculating the heart rate (HR) from an Electrocardiogram (ECG) is a fundamental skill in clinical practice. The standard ECG paper moves at a speed of 25 mm/second. This means each small square represents 0.04 seconds, and each large square (5 small squares) represents 0.2 seconds.

1. The 1500 Method (Small Squares)

This is the most accurate method for regular rhythms. Since there are 1,500 small squares in one minute (60 seconds / 0.04 seconds = 1,500), you count the number of small squares between two consecutive R-waves (the R-R interval) and divide 1,500 by that number.

Formula: 1500 / Number of small squares = HR (BPM)

Example: If there are 15 small squares between R-waves, 1500 / 15 = 100 BPM.

2. The 300 Method (Large Squares)

This is a quick way to estimate heart rate when the rhythm is regular. There are 300 large squares in one minute (60 seconds / 0.2 seconds = 300). You count the number of large squares between two R-waves.

Formula: 300 / Number of large squares = HR (BPM)

Example: If there are 4 large squares between R-waves, 300 / 4 = 75 BPM.

3. The 6-Second Method (Irregular Rhythms)

When the heart rate is irregular (like in Atrial Fibrillation), the methods above are inaccurate. Instead, clinicians look at a 6-second strip. On standard ECG paper, 30 large squares equal 6 seconds. You count the number of R-waves (QRS complexes) in that 30-square span and multiply by 10.

Formula: Number of R-waves in 6 seconds × 10 = HR (BPM)

Normal Values

  • Normal: 60 to 100 BPM
  • Bradycardia: Less than 60 BPM
  • Tachycardia: Greater than 100 BPM

Disclaimer: This calculator is for educational purposes only. Always consult with a qualified medical professional for clinical diagnosis or interpretation of medical tests.

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