Calculate Heart Rate in Ecg Strip

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ECG Heart Rate Calculator

This calculator helps you determine your heart rate from an electrocardiogram (ECG) strip.

Large Boxes

Note: A standard ECG strip has 5 small boxes within each large box.

mm/sec

Note: Common paper speeds are 25 mm/sec or 50 mm/sec.

Millimeters (mm) Seconds (sec)

Results:

Understanding ECG Heart Rate Calculation

The electrocardiogram (ECG or EKG) is a vital tool in diagnosing heart conditions. One of the most basic pieces of information derived from an ECG is the heart rate. Several methods can be used to calculate heart rate from an ECG strip, depending on the information available and the desired accuracy.

Method 1: Using Large Boxes (for regular rhythms)

This is the quickest and most common method for estimating heart rate when the heart rhythm is regular. The standard ECG paper is divided into small boxes (typically 1mm x 1mm) and larger boxes (typically 5mm x 5mm). Each large box represents 0.20 seconds (if paper speed is 25 mm/sec) or 0.16 seconds (if paper speed is 50 mm/sec).

The formula is:

Heart Rate (bpm) = 300 / (Number of Large Boxes Between Consecutive R-waves)

If the rhythm is slightly irregular, this method provides a good approximation.

Method 2: Using Small Boxes (for more precision or irregular rhythms)

For more precise calculations or when dealing with irregular rhythms, you can count the number of small boxes between consecutive R-waves (the peak of the QRS complex). Each small box typically represents 0.04 seconds (at 25 mm/sec).

The formula is:

Heart Rate (bpm) = 1500 / (Number of Small Boxes Between Consecutive R-waves)

Method 3: Using Actual Time Interval (R-R Interval)

If you know the exact time between R-waves (the R-R interval), you can directly calculate the heart rate.

The formula is:

Heart Rate (bpm) = 60 / (R-R Interval in Seconds)

How This Calculator Works

This calculator primarily uses the "Large Boxes" method for its simplicity and widespread use in clinical settings. You input the number of large boxes between two consecutive R-waves and the paper speed of the ECG machine. The calculator then applies the formula to estimate the heart rate in beats per minute (bpm).

Example Scenario:

Imagine you observe 4 large boxes between two consecutive R-waves on an ECG strip recorded at a standard speed of 25 mm/sec. Using the calculator:

  • Number of Large Boxes Between R-waves: 4
  • ECG Paper Speed: 25 mm/sec

The calculation would be: 300 / 4 = 75 bpm.

If you chose to input the R-R interval in millimeters and the paper speed is 25 mm/sec, 4 large boxes would equate to 20 mm (4 boxes * 5 mm/box). If you input '20' for RRI in mm and '25' for speed, the calculator determines the RRI in seconds (20mm / 25mm/sec = 0.8 sec) and then calculates 60 / 0.8 = 75 bpm.

Understanding these calculations can help healthcare professionals and students quickly assess a patient's cardiac rhythm.

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