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Heart Rate from RR Interval Calculator

Turn an RR interval into a heart rate in beats per minute.

How it is calculated

The RR interval is the time between two successive heartbeats, and a minute holds 60,000 milliseconds, so HR (bpm) = 60000 ÷ RR (ms). The tool also shows the RR in seconds, RR ÷ 1000, to two decimals. The heart rate is rounded to a whole number of beats per minute. A single RR gives an instantaneous rate, the rate if every beat were spaced that far apart, not an average over a minute. The RR must lie between 240 and 3000 ms, which is roughly 250 down to 20 bpm; anything outside that range, or an empty box, shows no result. Educational use only.

Worked example

An ECG shows an RR interval of 850 ms between two beats. Heart rate = 60000 ÷ 850 = 70.59, shown as 71 bpm. In seconds, 850 ÷ 1000 = 0.85 s. As a check, an RR of exactly 1000 ms gives 60 bpm and 800 ms gives 75 bpm, so 850 ms falls between them, closer to 70 bpm.

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Common mistakes

  • Entering the RR interval in seconds (0.85) instead of milliseconds (850). Values below 240 are rejected, so you get no result rather than a wrong rate.
  • Treating one beat-to-beat value as the person's resting heart rate. A single RR varies from beat to beat, so average many intervals before comparing with a resting rate.
  • Reading the whole-number bpm as exact. The result is rounded, so 70.59 shows as 71 and two nearby RR values can look identical.
  • Entering a heart rate and expecting the RR back. This tool goes only from RR to bpm; the reverse is 60000 divided by the bpm.
  • Using an RR measured across a missed or extra beat. Such a very long or very short gap gives a rate that does not reflect the underlying rhythm, and one beyond 3000 ms or under 240 ms is refused.

About this calculator

On an ECG or a chest-strap heart-rate monitor, the RR interval is the time in milliseconds between two consecutive R-wave peaks — the sharpest spike of each heartbeat's electrical signal. Because heart rate is simply how many of those beats occur per minute, the two are directly related by the formula HR = 60,000 ÷ RR interval (ms): a 1,000 ms RR interval corresponds to exactly 60 beats per minute, and an 800 ms interval to 75 bpm.

This conversion sits at the core of Holter monitors, fitness-tracker chest straps, and heart-rate variability (HRV) analysis, where researchers work with the raw RR series (sometimes called NN intervals when only normal beats are included) rather than a smoothed bpm figure, because RR intervals preserve the beat-to-beat timing detail needed to compute HRV metrics like RMSSD and SDNN.

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