Key Detector
Drop a song or type its chords. Find the key in seconds, right in your browser.
Drop a song here
MP3, WAV or M4A. Analysed in your browser: nothing is uploaded.
How to find the key of a chord progression
The key is the chord that feels like home. The finder runs the four checks below on your chords; you can run them by hand too.
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Which key contains all your chords?
C, G, Am and F all belong to C major (and to A minor). One chord outside the scale usually means a borrowed chord, not a new key.
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Where does it start and finish?
Progressions tend to leave from home and come back to it. Starting and ending on Am points to A minor; on C, to C major.
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Is there a five chord falling home?
A major or seventh chord a fifth above home, moving to home (G7 → C), is the strongest sign of the key.
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Check the relative minor
Every major key shares its chords with a minor key three half steps lower. Checks 2 and 3 decide between the two.
See why keys are neighbours on the circle of fifths, and how to find the key of a whole song in our step-by-step guide.
Hear the key
Every chord is in C major, and it starts on C, the home chord.
The same four chords as C major, but it starts on Am: the home moves, and the mood turns sad.
ii–V–I in C. The G7 resolves to Cmaj7, which settles the key.
Frequently asked questions
What key are these chords in?
Type or paste them above. The finder checks which keys contain all of your chords, then looks at where the progression starts, where it rests and whether a five chord resolves home, and tells you the key, how sure it is and why.
Why does it say C major or A minor?
A major key and its relative minor share exactly the same seven chords: C, Dm, Em, F, G, Am and B° belong to both C major and A minor. The chords alone cannot tell them apart; where the music starts and settles can. Am F C G feels like A minor, C G Am F feels like C major.
What if some of my chords are not in the key?
Songs borrow chords from neighbouring keys all the time: a B♭ in a C major song, for example. The finder marks those chords as outside the key and tells you which key they come from.
Can it find the key of a song from an audio file?
Yes. Drop an MP3, WAV or M4A on "A song" and it listens to which notes ring most, then matches them to the 24 major and minor keys. Your file is read by your browser and never uploaded. It is an estimate: it is usually right on clear, tonal music, and it can lean to the relative key (C major and A minor share every note), which is why it shows both.
How accurate is it?
On a set of songs with known keys it found the right key, or its relative, most of the time, and it tells you how sure it is: Clear, Likely or Close call. Heavy drums, a song that changes key, or a very quiet recording make it less sure. When it says Close call, listen for the chord where the song feels at home.
How do I find the key of a song without a tool?
Look at the first and last chords, listen for a five chord falling back to home, and check which key signature contains all of your chords. The four checks below walk through it.