Which files can I analyse?

MP3, WAV, M4A, AAC, FLAC, OGG and most other audio formats, plus the soundtrack of video files like MP4 and MOV.

Why does it say half or double the tempo I expected?

Beat detectors sometimes lock on to every other beat, or on to the hi-hat between beats. Play the song with the click and pick the half or double option if the click doesn't match the way you'd count it.

How accurate is the result?

For music with a steady beat, usually within about one BPM. Songs recorded without a click track, with tempo changes, or with no drums are harder, and the result is an average.

Why was no tempo found?

There was no steady pulse to lock on to. Speech, ambient pieces and very short clips often don't have one. Use the tap tempo BPM finder instead.

No. The file is decoded and analysed on your device, and never leaves your computer or phone.

Does it find the key of the song too?

No, only the tempo. Our online tuner can help you find individual notes if you play or sing along.

BPM Detector

Drop in a song and get its tempo in beats per minute. Then play it back with a click on every beat to check the detector got it right.

Your file is analysed on your device and never uploaded.

How it works

1Drop an audio or video file, or click to choose one.
2Read the detected BPM.
3Play it with the click track and switch to half or double if needed.

How the BPM detector works

The detector looks for regular bursts of energy in the music, which is where drums and strong chords land. It measures how often those bursts repeat and picks the tempo that explains them best, preferring values in the range most music is counted in. Everything runs in your browser, so even a long track takes only a few seconds and nothing is uploaded.

Checking the result by ear

A number on its own is easy to get wrong by a factor of two, so the detector lets you hear it. Play with click lines the click up with the strongest beats it can find in the song. If the click lands on every beat you'd tap your foot to, the tempo is right. If it only hits every other beat, choose double; if it's twice as busy as the beat, choose half.

When automatic detection struggles

Live recordings drift, classical music changes tempo on purpose, and songs with swing or heavy syncopation can confuse any detector. In those cases the result is an average over the whole file. For a quick check of a specific section, tap along with our BPM finder instead.

Uses for a song's BPM

DJs use BPM to choose tracks that mix smoothly. Video editors cut on the beat, runners and cyclists build playlists at a target cadence, and musicians set a metronome to practise a song at full speed or slowed down. If you need the song at a different tempo, our speed changer can stretch it without changing the pitch.