How to Calculate Heart Rate Using the 1500 Method

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ECG 1500 Method Calculator

Count the 1mm small boxes between two consecutive R-wave peaks on the EKG strip.

function calculateBPM() { var smallSquares = document.getElementById("smallSquares").value; var resultArea = document.getElementById("resultArea"); var output = document.getElementById("heartRateOutput"); var classification = document.getElementById("classificationOutput"); if (smallSquares === "" || smallSquares <= 0) { alert("Please enter a valid number of small squares."); resultArea.style.display = "none"; return; } var bpm = 1500 / parseFloat(smallSquares); var roundedBpm = Math.round(bpm); output.innerHTML = roundedBpm + " BPM"; resultArea.style.display = "block"; var category = ""; if (roundedBpm 100) { category = "Classification: Tachycardia (Fast)"; } else { category = "Classification: Normal Sinus Rhythm"; } classification.innerHTML = category; }

How to Calculate Heart Rate Using the 1500 Method

In clinical electrocardiography (ECG/EKG), the 1500 method is widely considered the most accurate manual technique for calculating heart rate when the cardiac rhythm is regular. This method provides a precise beats-per-minute (BPM) measurement by analyzing the interval between consecutive R-waves (the highest peaks on the ECG strip).

Why Use the 1500 Method?

Standard ECG paper moves at a speed of 25 millimeters per second. This means that in one minute (60 seconds), the paper covers 1,500 millimeters. Since each small square on the ECG grid is exactly 1 millimeter wide, there are 1,500 small squares passing through the machine every minute. By dividing 1,500 by the number of small squares between heartbeats, you determine the exact heart rate.

The Formula

Heart Rate (BPM) = 1500 / Number of Small Squares (R-R Interval)

Step-by-Step Calculation Guide

  1. Identify the R-waves: Locate two consecutive R-wave peaks (the sharp upward spikes) on the ECG strip.
  2. Count the Small Squares: Count the number of 1mm boxes between those two peaks. For example, if there are 3 large boxes and 2 small boxes, the total is 17 small squares (each large box contains 5 small squares).
  3. Apply the Math: Divide 1500 by that number.
  4. Example: If you count 15 small squares between R-waves, the calculation is 1500 รท 15 = 100 BPM.

When to Avoid This Method

While highly accurate for regular rhythms, the 1500 method should not be used for irregular rhythms, such as Atrial Fibrillation. In cases of irregular heartbeat, clinicians use the "6-second strip method," which involves counting the number of R-waves in a 6-second interval and multiplying by 10.

Quick Reference Table

Small Squares BPM Category
10 150 Tachycardia
15 100 Normal (Upper)
20 75 Normal
25 60 Normal (Lower)
30 50 Bradycardia

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