BPM Detector
Find the tempo of any song: drop an audio file, get its BPM with a confidence rating, and play it back with a click track to hear whether the beat lines up. The file never leaves your device.
BPM Detector
Songs are read by your browser and never uploaded. Nothing leaves your device.
Runs in your browser. Files and audio never leave your device.
Scratchpad auto-saved
How it works — in four simple steps
No signup and nothing to install — it all runs in your browser.
Drop a song
Any common audio format.
Read the BPM
With confidence and alternatives.
Play with clicks
Check that the clicks sit on the beat.
Adjust
Switch to ½× or 2× if it feels off.
If the clicks feel twice too fast or slow, press ½× or 2×. Tempo is often ambiguous by an octave.
Features
Any audio your browser plays
MP3, WAV, M4A/AAC, OGG, Opus and FLAC.
Precise
Spectral-flux onsets, autocorrelation and sub-frame refinement to 0.1 BPM.
Half and double time
One click to switch between ½×, 1× and 2×.
Click track
Hear the song with clicks on the detected beat.
Confidence
High, medium or low, plus other tempo candidates.
Tap to check
Tap along to compare with your own count.
About the BPM Detector
The detector decodes the audio with your browser's own decoder, then listens for onsets, the moments where sound suddenly gets louder in some frequency band, like a kick drum, a strum or a hi-hat. It splits up to two minutes of the track into 12-millisecond frames, measures how much the spectrum jumps in each (the spectral flux), and builds an onset curve. Autocorrelation then finds the time gap at which that curve best lines up with itself, which is the beat period. A comb of beat multiples and a fine sub-frame search make the estimate precise to a tenth of a BPM.
Tempo is ambiguous by nature. A drum-and-bass track at 174 BPM can also be felt at 87, and a slow ballad at 70 might be counted at 140. The detector picks the most likely reading, nudged gently towards the 80–160 BPM range where most music sits, and offers ½× and 2× buttons for the alternatives. Play with click track plays the song with a click on every detected beat, aligned to the strongest beat position, so you can hear straight away whether it's right.
It works best on music with a steady beat: pop, rock, hip-hop and electronic. Tracks with tempo changes, rubato, or no percussion give a lower confidence. You can also tap along with the button below the result to check by ear.