Key & BPM Finder
Find the musical key, Camelot code and tempo of any track. Drop files one after another to build a table, then export it as CSV. Analysis runs entirely in your browser.
Drop a track to find its key and BPM
or choose an audio file
MP3 · WAV · FLAC · AAC · M4A · MP4 · OGG · OPUS · up to 25 MB
Your audio stays on your device
This tool decodes, analyses and exports your track entirely in your browser. The file is never uploaded to our servers, and nothing is stored when you close the tab.
- Free
- No account
- Browser processing
How the Key & BPM Finder works
Tempo comes from a spectral-flux onset envelope: the tool measures how much energy rises between successive short-time spectra, which produces a spiky signal that peaks on note and drum attacks. Autocorrelating that envelope reveals the periodicity of the pulse, and the strongest peak in a musically plausible range becomes the BPM estimate.
Key comes from a chromagram. Every frequency bin is folded into one of the twelve pitch classes, weighted by energy and averaged over the track, which produces a fingerprint of how much each note is used. Correlating that fingerprint against the Krumhansl-Schmuckler profiles for all 24 keys gives both the most likely key and a measure of how clearly it beats the alternatives.
Both methods are decades-old, well documented and deliberately transparent. Nothing here is a black box, and where the method is weak the confidence value shows it rather than hiding it behind a confident-looking number.
Using key and BPM for harmonic mixing
Harmonic mixing means choosing the next record so its key sits comfortably against the one already playing. With Camelot codes the rule is simple: stay on the same number, move one number up or down, or switch letter at the same number. 8A into 8B, 9A or 7A will all sit well; 8A into 3B will not.
Tempo matters just as much. A four to six percent tempo change is usually inaudible with modern time-stretching, but larger jumps either change the pitch, which breaks your key planning, or introduce artefacts. Sorting a crate by BPM and Camelot code is the fastest way to build a set that flows.
- Same Camelot code: a perfect harmonic match
- ±1 on the wheel: the standard smooth transition
- Same number, different letter: relative major/minor, an easy mood change
- +7 on the wheel: an energy lift, use sparingly
Where the estimates break down
Key detection assumes a track stays in one key. Music that modulates, borrows heavily from parallel modes or leans on chromatic harmony will produce a low-confidence answer that is best treated as a hint. Drum-only tracks, sound design and heavily atonal material have no key to find, and the result there is noise however confident it looks.
Tempo detection assumes a steady pulse. Live performances with rubato, ritardando or a drifting drummer produce an average rather than a grid. If a track has an intro at a different feel, the estimate is dominated by whichever section is longer.
Frequently asked questions
The track is folded into a chromagram — the energy in each of the twelve pitch classes across the whole recording — and that profile is correlated against the Krumhansl-Schmuckler key profiles for all 24 major and minor keys. The best-matching key wins, and the margin over the runner-up becomes the confidence value.