Detects (or takes) a track's current BPM, works out the exact playback-speed percentage needed to hit your target tempo, and applies it with pitch preserved — handy for DJs and mashup/mixtape prep.
The Tempo Matcher changes a track’s BPM to a target value without altering its pitch. DJs use it to line up two songs, producers to fit a loop to a project tempo, and dancers or musicians to practise at a specific speed.
You get an automatic tempo reading, an exact speed-factor calculation (target ÷ current) and a pitch-preserving WSOLA time-stretch.
Tempo detection computes a spectral-flux onset envelope (24 log-spaced bands), autocorrelates it with a perceptual tempo prior, refines the peak with a comb filter to about 0.05 BPM, and reports the beat phase. The matcher then calls the same engine as the Speed Changer with factor = target ÷ source.
Align a 126 BPM track to a 128 BPM set.
Fit a sample to the project tempo.
Set music to an exact routine tempo.
Slow a track to a target BPM.
| Ratio limit | 0.4×–2.5× (best within ±10%) |
|---|---|
| Detection accuracy | ≈ ±0.1 BPM on steady rhythms |
No. Pitch is preserved by default.
From the rhythm of onsets in the audio, not from file tags.
Yes — it uses the same pitch-preserving time-stretch as the Audio Speed Changer, so tempo changes without the track sounding sped-up or slowed-down in pitch.
Roughly within 50%–200% of the original speed (a big range) the time-stretch algorithm holds up reasonably well; very large jumps (say, doubling or halving tempo) will sound noticeably processed.
This tool runs entirely in your browser using the Web Audio API. Nothing is uploaded, stored or shared — there is no server to send your file to, so it works offline once the page has loaded.
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