Find the key of a song from its audio
Upload an audio file and find out what key the song is in, major or minor, and its tempo in BPM as a bonus. Handy when you want to play along, sing it in your range or mix it with another track.
Press “Choose an audio file” and choose the song: the analysis starts on its own on our server, and when it finishes you see the result with a link to the scale of that key.
The tool opens right here in your browser when the page finishes loading.
What the key of a song tells you
The key is the note a song gravitates to (the tonic) and whether it is major or minor: G major or E minor, for example. It tells you which scale to improvise with, which chords to expect and whether you should move the song up or down to sing it comfortably.
How this song key finder works
It uses the Krumhansl-Schmuckler method: it measures how much each of the 12 notes sounds across the whole song and compares that profile with those of the 24 major and minor keys. The closest match wins. Then, if the chords of the song point to the relative key (A minor rather than C major, for instance), it corrects the result.
The key is spelled the way musicians write it: you will see B♭ major, not A♯ major. If the server is busy or can't handle the file, the key is worked out in your browser with the same method, less reliably, and the page tells you so.
What it tells you and what it doesn't
- One key: the main key of the whole song. If the song modulates, you get the one that dominates.
- Major or minor: it doesn't tell modes like Dorian or Mixolydian apart; to learn them, see the guitar modes.
- The tempo: the BPM of the song, from the same analysis.
- No chords: for the chords, use Chord AI, which also gives you the key and the tempo.
Frequently asked questions
How do I find out what key a song is in?
Upload the audio with “Choose an audio file” and wait for the result: you will see the key (E minor, for example) and the tempo. To do it by ear, listen for the note the song comes to rest on at the end of its phrases: it is usually the tonic.
Is the song key finder free?
Yes, and it needs no sign-up. It takes files up to 30 MB and songs up to 5 minutes long, in MP3, WAV, FLAC, M4A, OGG and other audio formats.
Can I get the key and the BPM at the same time?
Yes: the result includes the tempo in BPM. If you only need the tempo, the BPM detector measures it in your browser without uploading the audio.
Does it detect modes like Dorian or Mixolydian?
No, only major and minor keys (24 in all). A song in D Dorian, for example, may come out as D minor or as C major, which shares its notes.
What if the song changes key?
The key finder gives one key for the whole song: the one that dominates. To follow the changes, get the chords with Chord AI and look for the places where chords from another key turn up.
How do I move the chords to another key?
Once you know the key, use the Full Partituras chord transposer to move the chords up or down to the key that suits you.
Is the audio I upload stored?
Not on the server: it is deleted as soon as the analysis ends, and this analysis creates no files. Your browser keeps a copy of the audio and the result so you don't have to upload it again; you can clear them in your browser settings.