ECG Heart Rate Calculator
Estimate heart rate from an ECG using the classic small-box method (1500 ÷ R-R) for fast bedside calculation.
What is ECG Heart Rate?
Reading an ECG strip's heart rate is a fundamental clinical skill. The 1500-method works at the standard paper speed of 25 mm/s, where each small box equals 0.04 s. Counting boxes between two R waves and dividing 1500 by that count gives the rate in beats per minute.
How is it calculated?
HR (bpm) = 1500 / number of small boxes between two consecutive R waves. The large-box method (300 ÷ large boxes) is faster but less precise for very fast or very slow rhythms.
Frequently Asked Questions
- What if the rhythm is irregular?
- Count R waves over a 10-second strip and multiply by 6.
- Why 1500?
- 60 s × 25 mm/s ÷ small-box length 0.04 s ÷ 1 R-R interval.
- Can apps measure HR from an ECG?
- Yes — modern wearables do this in real time.