Heart Rate from RR Interval Calculator

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.

Enter an RR interval in milliseconds and this calculator returns the equivalent instantaneous heart rate in beats per minute.