ECG Heart Rate Calculator

Determines HR in beats per minute based on RR interval distance or cycle length in msec.

Refer to the text below the calculator for more information about deriving heart rate from ECG findings.

The distance between the R wave peaks from two successive QRS complexes on an electrocardiogram can be used to derive the heart rate in beats per minute. Adult heart rate normal range varies between 60 and 100 beats per minute.

Method 1

  • RR duration = RR interval in mm / 25 (or 50 if paper speed is of 50mm/s)
  • Heart rate in bpm = 60 / RR duration

Method 2

  • Heart rate in bpm = 60,000 / Cycle length in msec

RR Interval
RR Interval Distance
Paper Speed
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Cycle Length

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Heart Rate from ECG

One of the first steps to interpreting an electrocardiogram is the calculation of the heart rate. In a regular rhythm ECG, the heart rate may be derived from counting the number of large and small squares between two QRS complexes and examining the RR interval distance.

This method has two steps:

  • Step 1. RR duration = RR interval in mm* / 25 (or 50 if paper speed is of 50mm/s)
  • Step 2. Heart rate in bpm = 60 / RR duration

* If the RR interval is defined in number of small (1 mm) or big (5 mm) boxes then the number of boxes is multiplied by their dimension, to determine the RR interval in mm.

The distance on the horizontal axis between two elements of the QRS complex on ECG paper corresponds to a certain duration, as reflected in the paper speed. The most commonly met paper speed is 25 mm/s, but in some cases, speeds of 50 mm/s may also be met.

The heart rate may also be estimated from cycle length:

  • Heart rate in bpm = 60,000 / Cycle length in msec

Adult heart rate normal range varies between 60 and 100 beats per minute. Lower than 60 bpm is indicative of bradycardia whilst more than 100 bpm is indicative of tachycardia. During physical exercise, heart rate increases to ensure sufficient oxygenated blood is carried through the body, particularly to the exerted muscles.



Oba Y, Hoshide S, Kabutoya T, Kario K. Increased Resting Heart Rate on Electrocardiogram Relative to In-office Pulse Rate Indicates Cardiac Overload: The J-HOP Study. Am J Hypertens. 2018; 31(10):1106-1112.

Becker DE. Fundamentals of electrocardiography interpretation. Anesth Prog. 2006 Summer; 53(2):53-63; quiz 64.

Specialty: Cardiology

Article By: Denise Nedea

Published On: July 1, 2020

Last Checked: July 1, 2020

Next Review: July 1, 2025