Find the BPM of a song

The finder reads the song's spectrum about 86 times a second and marks every moment the sound gets suddenly louder in some band: a kick, a snare, a strum, a new chord. Those onsets repeat at the beat, so it measures how well the onset pattern lines up with itself at every tempo from 50 to 220 BPM, and keeps the one that lines up best at one, two, three and four beats.

It then places each beat in the song, and the BPM comes from the spacing of all the beats rather than one guess, which is why it reads to a tenth of a BPM: 127.9, not "about 128".

A song at 140 BPM can also be counted at 70, and a ballad at 70 at 140: both are the same pulse, one counting every beat and the other every second one. The finder gives the count most listeners tap and shows half and double beside it, so you can pick the one your DJ software, DAW or drummer uses.

Press play and a click sounds on every beat it found. If the clicks sit on the kick and snare all the way through, the BPM is right. You can also tap along with the Tap button and compare.

• Drop as many songs as you like: each is analysed in turn, and a table fills with BPM, key and Camelot code.
• Download it as CSV for Excel, Numbers or Google Sheets, sorted however you plan your set.
• Pick any row to hear that song with its click.

Live drummers drift, and some songs speed up, slow down or change time. The finder follows the beat as it moves and reports the song's main tempo. For a song with no steady pulse, like rubato piano or ambient, it says it found no clear beat instead of making one up.