Tempo - Beats Per Minute

Beats per minute (BPM) is a unit typically used as a measure of tempo in music and heart rate.

The BPM tempo of a piece of music is conventionally shown in its score as a metronome mark, as illustrated to the right. This indicates that there should be 120 crotchet beats (quarter notes) per minute. In simple time signatures it is conventional to show the tempo in terms of the note duration on the bottom. So a 4/4 would show a crotchet (or quarter note), as above, while a 2/2 would show a minim (or half note).

In compound time signatures the beat consists of three note durations (so there are 3 quavers (eighth notes) per beat in a 6/8 time signature), so a dotted form of the next note duration up is used. The most common compound signatures: 6/8, 9/8, and 12/8, therefore use a dotted crotchet (dotted quarter note) to indicate their BPM.

Exotic time and particularly slow time signatures may indicate their BPM tempo using other note durations. BPM became common terminology in disco because of its usefulness to DJs, and remain important in the same genre and other dance music.

In this context the beats measured are either crotchets (quarter notes) in the time signature (sometimes ambiguously called down-beats), or drum beats (typically bass-drum or another functionally similar synthesized sound), whichever is more frequent. Higher BPM values are therefore achievable by increasing the number of drum beats, without increasing the tempo of the music. House music is faster around 120–128 BPM (from regular house music to UK Garage), Trance Music ranges from 125 to 150 BPM, and Jungle music generally ranges between 150–180 BPM. Psytrance is almost exclusively produced at 145 BPM, whereas Speedcore and Gabber music exceed 180 BPM.