C major 4/4 diatonic
Song Key Finder / Scale Helper
Paste chords from a song and compare likely keys, major or minor. See confidence scores, diatonic chords, outside-key color, and scales that fit.
piano Chords 4 parsed
Most likely key
C major 91%
4 of 4 chords match cleanly. 0 chords flagged as outside-key color.
CGAmF
Key candidates
A minor 4/4 diatonic
F major 3/4 diatonic
D minor 3/4 diatonic
G major 3/4 diatonic
Diatonic chords in C major
I C
ii Dm
iii Em
IV F
V G
vi Am
vii° Bdim
Scales to try
C major
C D E F G A Bhome scale for melody and harmony
C major pentatonic
C D E G Asimple hooks and guitar-friendly lead lines
A minor pentatonic
A C D E Grelative minor color over the same key center
G mixolydian
G A B C D E Fdominant color over V chords
How to read the result
A high score means the chords mostly behave like the diatonic chords of that key. Short loops can still point to both a major key and its relative minor, so listen for the chord that feels resolved rather than choosing by math alone.
Outside-key chords are useful musical color. A7 in C major, for example, often points toward D minor; a borrowed iv chord can add a darker sound in a major song. Use the highlight as a map for tension, not as a warning to remove the chord.
What to do with close matches
Short loops often produce two strong answers: a major key and its relative minor. When the scores are close, check the first bass note, final chord, melody landing notes, and the chord that sounds most stable when you stop playback.
If a verse and chorus point to different centers, label them separately. A song can sit in A minor for the verse and open into C major for the chorus without either section being wrong.
How to use the scale suggestions
Start with the main major or minor scale for melodies, then try pentatonic scales for simpler hooks and solos. Harmonic minor is useful when a minor progression uses a major V chord, while Mixolydian and Dorian suggestions can explain modal color.
Frequently Asked Questions
How does the song key finder choose a key?
It parses the chord roots and qualities, then compares them against all 12 major and 12 minor diatonic chord sets. Chords that match the expected scale degree score highest, tonic chords get a small boost, and outside chords lower the score.
Can a song have chords outside the key?
Yes. Borrowed chords, secondary dominants, modal mixture, and passing diminished chords are common. The tool highlights likely outside-key chords instead of treating them as errors.
Why do two keys sometimes have similar confidence?
Relative major and minor keys share the same notes, so short progressions can be ambiguous. Use the first and last chord, melody note, bass emphasis, and where the song feels resolved to choose between close candidates.
Does it understand slash chords and sevenths?
Yes for key detection basics. It reads the main chord root and quality from symbols like Cmaj7, Dm7, G7, F#dim, or C/E, while the bass note and extensions are treated as color.