Estimate heart rate using large squares, small squares or a six-second strip.
For a regular rhythm, divide 300 by the number of large boxes between two R waves. For example, 300 ÷ 4 large boxes = 75 bpm.
Use it for irregular rhythms. Count the QRS complexes in a 6-second strip and multiply by 10.
The 300 method uses large boxes for a quick estimate, while the 1500 method divides 1500 by the number of small boxes for a more precise rate on regular rhythms.
A common adult resting range is about 60 to 100 bpm, but any rate must be interpreted with the patient's stability and clinical picture.
No. It estimates rate and offers a rhythm checklist for study. Real ECG interpretation requires full patient assessment and qualified clinical review.
These answers are for nursing education and exam practice only and do not provide patient-specific medical advice.
When to use: Best for a regular rhythm; quick bedside estimate. Box-count methods assume standard ECG paper speed of 25 mm/s.
Rhythm checklist
Safety
Educational use only. ECG interpretation in real clinical care requires full patient assessment and qualified clinical review. This tool does not diagnose rhythms.
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