Song Key Finder
Song Key Finder detects the key of a song from an audio file. Upload a track to see its most likely key with a confidence score, its relative key, the other keys it could be in, and the notes, chords and modes of that key — every note spelled the way the key signature writes it. Free, with no signup.
How to find the key of a song
- 1
Upload the song
Drop an audio file on the page or choose one: MP3, WAV, FLAC, AAC, M4A, OGG, Opus, WebM or AIFF, up to 50 MB.
- 2
Wait for the analysis
The file is analyzed on our server, which can take up to a minute for a full-length song, and deleted as soon as the result is ready.
- 3
Read the key
See the most likely key with its confidence, the relative major or minor that shares its notes, and the other keys the song could be in.
- 4
Explore the key
Play the key's scale, its chords and the modes that share its notes, or copy the key to use elsewhere.
Check the result by ear
Automatic detection is a fast first answer. To confirm it, play the key's scale and chords along with the song: if they fit and the song feels resolved on the key's home chord, the key is right. If the song rests on the relative key's home chord instead, it's in the relative key.
Using the key
Knowing the key tells you which scale to improvise or write a melody in, which chords will fit, and how far to transpose to suit a singer. DJs use keys to mix harmonically, blending tracks in the same or neighboring keys; the key is shown in standard notation, such as A minor, which converts directly to Camelot codes.
Frequently Asked Questions
What key is this song in?
Upload the song and the Song Key Finder reports its most likely key, such as G major or E minor, with a confidence score. It also lists the other keys the song could be in, so you can check close calls.
How does the key detection work?
A neural network trained to recognize keys listens to the whole recording and gives a probability for each of the 24 major and minor keys. The most probable key is the result, and its probability is the confidence. The BPM Finder uses the same analysis, so both tools give the same key.
What does the confidence mean?
It's how much of the model's weight goes to the detected key. A high score means one key clearly fits best. Below 50%, the song may change key, borrow chords from other keys, or sit between a major key and its relative minor — check the other keys listed and confirm by ear.
Why does it show a relative key?
Every major key has a relative minor that uses exactly the same notes, such as C major and A minor. Because they share their notes, they're the easiest pair to confuse; the note the song feels resolved on tells you which one it's in.
Why is the key spelled with flats or sharps?
Keys and their notes are spelled the way their key signatures write them: B♭ major rather than A♯ major, with E♭ as its fourth note. Every note in the scale keeps its own letter.
Is my audio file stored?
No. The file is sent to our server for analysis and deleted as soon as the result is ready. Playback on the page uses the copy on your device.
Which audio files can I upload?
MP3, WAV, FLAC, AAC, M4A, OGG, Opus, WebM and AIFF files up to 50 MB.
What's the difference between the Song Key Finder and the BPM Finder?
Both detect the key with the same analysis. The BPM Finder also measures the tempo; the Song Key Finder adds the other likely keys and the key's scale, chords and modes.
Is the Song Key Finder free?
Yes. It's free to use with no account.
Related Music Tools
BPM Finder
Find the exact BPM and key of any song. Upload an audio file for automatic tempo and key detection, or tap along to the beat. Free, no signup.
Scale Finder
Find 33 scales and modes in every key with correctly spelled notes, piano and guitar diagrams, diatonic chords and playback. Free online scale finder.
Chord Progression Generator
Build chord progressions in all 12 keys, in major, minor and five modes, with correctly spelled chords. Play them on piano and copy them for your song.
About Song Key Finder
Upload a song to find its key, with a confidence score, the relative key, other likely keys, and the key's scale, chords and modes. MusicToolSet provides free online music tools for musicians, producers, DJs, and music students. No signup required, no downloads needed — use every tool right in your browser.