Song key & BPM finder
Drop a song or a loop. You get the key with its relative, the tempo with the half- or double-time alternative, and a meter guess, in a few seconds. Nothing is stored: the file is analysed in memory and forgotten.
Drop a song here, or
WAV, FLAC, AIFF or MP3 · up to 6 minutes · 100 MB · free, nothing to install
What you get
The key (for example A minor, with C major as its relative), a confidence bar, the tempo in BPM with the other octave next to it, the meter guess and the length. Copy it as text for your notes, or drop the same file on the stem splitter or the drum transcriber.
How it works
Pure signal processing, no model: the harmony of the whole file is folded into twelve pitch classes and matched against the standard key profiles; the rhythm comes from how the sound's onsets repeat. It is fast and dependable on songs with clear harmony and a steady beat, and honest about its confidence when they are not.
Questions
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What does it analyse?
The whole file: a 12-bin chroma of the harmony is matched against the Krumhansl-Schmuckler key profiles for the key, and an onset envelope's autocorrelation gives the tempo. The meter is a guess from how the accents repeat and is labelled as such.
Why two BPM values?
Tempo is ambiguous by an octave: a 64 BPM ballad and a 128 BPM track share a pulse. The first value is the more likely one; the second is the half- or double-time alternative. If the first feels wrong, the second is usually it.
How accurate is the key?
Confident on songs with clear harmony; less so on drum loops, ambient pads or heavily detuned material. The confidence bar shows the gap between the best key and the runner-up. The relative key is always shown: songs in A minor and C major share the same notes.
Is my file stored?
No. The file is analysed in memory on our server and forgotten as soon as the numbers come back. Nothing is stored and nothing is written to disk.
Do I need an email?
No: the result is shown on the page. Only downloads elsewhere on the site, such as stems and MIDI files, ask for an email address once per browser.
How long can the file be?
Up to six minutes, WAV, FLAC, AIFF or MP3, 100 MB at most. A four-minute song is analysed in a few seconds.