ECG Heart Rate Calculator
Derive heart rate (bpm) from an ECG reading using three clinical methods: the RR interval in milliseconds, the 1500 rule on standard paper, or the 6-second strip count.
Measurement method
ms
Beats per minute derived from the ECG measurement
- 1
RR interval
800 ms - 2
Heart rate
60,000 ÷ 800 = 75
How does this calculator work?
Heart rate from an ECG is 60,000 ÷ RR_interval_ms for regular rhythms; on standard 25 mm/s paper use 1,500 ÷ small_squares. For irregular rhythms, count R waves in a 6-second strip and multiply by 10. Normal adult resting range is 60–100 bpm.
Formula
How this is calculated
An ECG records the heart's electrical activity over time. The RR interval is the time in milliseconds between two consecutive R peaks — the sharp upward spikes on the trace. Because there are 60,000 ms in a minute, dividing 60,000 by the RR interval gives the heart rate in beats per minute (bpm). This is the most precise method for regular, steady rhythms.
On standard ECG paper running at 25 mm/s, each small square represents 0.04 seconds (40 ms). Since 1,500 small squares equal exactly one minute (60 s ÷ 0.04 s/square), dividing 1,500 by the number of small squares between two R peaks gives the heart rate directly — the classic '1500 rule' taught in clinical training. It requires a regular rhythm where consecutive RR distances are approximately equal.
For irregular rhythms such as atrial fibrillation, where the RR distance varies beat to beat, the 6-second strip method is preferred. A 6-second segment (usually delimited by timing marks on the ECG paper) is inspected, the R peaks are counted, and the total is multiplied by 10 to extrapolate to 60 seconds. In adults, a resting heart rate of 60–100 bpm is normal; below 60 is bradycardia, above 100 is tachycardia. Always interpret ECG findings in full clinical context — this calculator is an educational tool, not a diagnostic instrument.
Frequently asked questions
The RR interval method is the most accurate for regular rhythms, measuring the exact time between beats. The 6-second method is preferred for irregular rhythms like atrial fibrillation because it averages multiple beats.
On standard ECG paper at 25 mm/s, one minute contains 1,500 small squares (60 s ÷ 0.04 s per square). Dividing 1,500 by the number of small squares between two consecutive R peaks gives the heart rate in bpm — a quick bedside calculation for regular rhythms.
A normal adult resting heart rate is 60–100 bpm. Below 60 is bradycardia (often normal in trained athletes) and above 100 is tachycardia. Always interpret ECG findings in full clinical context.
Also known as
TG we-Calculate Editorial Team. (2026). ECG Heart Rate Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/ecg-heart-rate-calculator
TG we-Calculate Editorial Team. "ECG Heart Rate Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/ecg-heart-rate-calculator.
TG we-Calculate Editorial Team, "ECG Heart Rate Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/ecg-heart-rate-calculator
@misc{wecalculate_ecg_heart_rate_calculator, title = {ECG Heart Rate Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/ecg-heart-rate-calculator}}, year = {2026}, note = {TG we-Calculate} }
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