Beat Finder

A BPM detector answers how fast — one number for the whole track. A beat finder answers when — the timestamp of each individual beat. If you're beatmatching you only need the tempo; if you're cutting a loop, placing a sample, or syncing video to music, you need the positions.

It's the offset from the start of the file to the first downbeat. Most tracks have a fraction of a second of silence or a pickup before the beat proper starts. Trimming to that offset, or using it as your loop start, is what makes an exported loop sit in time instead of drifting.

The bar grouping does — beats are grouped in fours because the overwhelming majority of popular music is in 4/4. The beat positions themselves are time signature agnostic. If your track is in 3/4 or 6/8, read the beat times and ignore the bar column, or use the Time Signature Finder first.

The grid is generated at a constant tempo from the detected BPM, then anchored to a real onset. That's what you want for programmed and produced music, which is almost always on a fixed grid. For a live performance that speeds up and slows down, the grid will drift away from the audio over time.

Audio without percussive transients — ambient pads, solo vocals, sustained strings — has no onsets to lock onto, and the tool reports nothing rather than fabricating a grid. It also rejects signals that are too uniform in level to contain a real beat.

The first 90 seconds. Tempo is stable across a track in the vast majority of cases, so that window is enough to establish the grid, and capping it keeps the analysis fast in the browser.