300 Method (Large Boxes between R-waves)
1500 Method (Small Boxes between R-waves)
6-Second Method (QRS complexes in 30 large boxes)
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input.placeholder = 'e.g. 4';
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input.placeholder = 'e.g. 20';
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label.innerText = 'Number of QRS Complexes (in 6 seconds):';
input.placeholder = 'e.g. 7';
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bpm = 300 / val;
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bpm = 1500 / val;
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bpm = val * 10;
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var roundedBpm = Math.round(bpm);
var interpretation = '';
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if (roundedBpm 100) {
interpretation = 'Tachycardia';
bgColor = '#ffebee';
textColor = '#b71c1c';
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interpretation = 'Normal Sinus Rhythm Range';
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' + roundedBpm + ' BPM
' +
'
Classification: ' + interpretation + '
';
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Guide to Calculating Heart Rate on an EKG
Understanding how to calculate heart rate from an electrocardiogram (EKG/ECG) strip is a vital clinical skill. Depending on whether the heart rhythm is regular or irregular, different mathematical methods are applied to ensure accuracy.
1. The 300 Method (The Sequence Method)
The 300 method is the quickest way to estimate heart rate for regular rhythms. It involves counting the number of large boxes (5mm) between two consecutive R waves (the R-R interval).
Formula: 300 / Number of Large Boxes
Example: If there are 3 large boxes between R waves, the rate is 300 / 3 = 100 BPM.
The 1500 method is the most precise for regular rhythms. Since standard EKG paper moves at 25 mm/sec, there are 1,500 small boxes (1mm) in one minute of recording.
Formula: 1500 / Number of Small Boxes
Example: If there are 20 small boxes between R waves, the rate is 1500 / 20 = 75 BPM.
3. The 6-Second Method
This is the preferred method for irregular rhythms (like Atrial Fibrillation). Because the distance between R waves varies, you must count the number of QRS complexes over a specific period of time.
Formula: Number of QRS complexes in a 6-second strip × 10
How to identify 6 seconds: Standard EKG paper has "hash marks" at the top indicating 3-second intervals. Two of these intervals equal 6 seconds (or 30 large boxes).
Example: If you count 8 QRS complexes in a 6-second strip, the rate is 8 × 10 = 80 BPM.
Normal vs. Abnormal Heart Rates
Classification
Rate (BPM)
Bradycardia
Less than 60
Normal Range
60 – 100
Tachycardia
Greater than 100
Note: This calculator is for educational purposes. Always consult a medical professional for clinical diagnosis and interpretation of EKG results.