How to find the BPM of a song
- Click Choose a song or drop an audio file onto the box. MP3, WAV, M4A, OGG and FLAC all work.
- Wait a few seconds while the beat is found. The tempo appears in large numbers, with half and double time readings next to it.
- Press play with Play a click on every beat ticked to check it by ear, or tap along with the Tap button or the T key.
How the tempo is found
The detector first looks for onsets: the moments when a new sound starts, such as a drum hit or a plucked note. It splits the audio into slices about 12 milliseconds apart, measures how much the energy in each frequency rises from one slice to the next, and adds those rises up. The result is a curve with a peak at every hit.
Beats repeat at a steady interval, so that curve lines up with itself when shifted by one beat, two beats and so on. The detector scores every tempo from 40 to 240 BPM by how well the curve matches itself at those shifts, with a gentle preference for the 80 to 160 BPM range where most music sits. The best score is then refined over many beats for the decimals, and the beat positions are found so the click track lands on the beat.
What BPM is used for
- DJing and mixing: songs with close tempos blend smoothly; a 124 BPM track can be mixed into a 126 BPM one with a small pitch adjustment.
- Running and workouts: many runners match music to their step rate, often 160 to 180 steps a minute.
- Practising an instrument: set a metronome to the song’s tempo, or slower while learning.
- Video editing: cut to the beat by knowing exactly how many seconds each beat lasts: 60 divided by the BPM.
To change a song’s tempo once you know it, use change audio speed: a 120 BPM song at 1.05× becomes 126 BPM.