What key is this song in?
Type the chords in the order the song plays them, or tap them in. The three keys they fit best appear as you go, each with the chords as roman numerals.
Or tap: pick a root, then a type
Best-fitting keys
- Type or tap at least one chord.
Transpose
How the finder decides
Each chord you enter is checked against all 24 major and minor keys. A chord belongs to a key when every one of its notes is in that key's scale; in a minor key the major V and V7 count too (E and E7 in A minor), because most minor-key songs raise the seventh note to get them. A key scores one point per chord that belongs, plus a bonus when the first chord (0.6) or the last chord (0.5) is its home chord, I or i. The top three are shown, with the chords that do not belong named as borrowed.
Worked example: Am, Dm, E7. In A minor all three belong (E7 as the raised-seventh V) and the first chord is the home chord: 3.6 points, "3 of 3 fit, E7 as the raised-seventh V". In C major, Am and Dm belong but E7's G# is not in the C major scale: 2 points, "2 of 3 fit (E7 borrowed)". So A minor wins, although A minor and C major share every note of their scales.
G, C, D, Em fit G major and E minor equally (4 of 4 each, the same seven notes). G major ranks first because the list starts on G (4.6 against 4.5); a song that starts and ends on Em is scored the other way. Both are shown, so you can pick by ear.
Chord symbols are read the way song sheets write them: Em, F#m7b5, Bbmaj7, C/E (the bass note is ignored for the key), and the aliases Amin or A- for Am, CM7 or CΔ for Cmaj7, B° for Bdim and Bø for Bm7b5. The 24 chord types that have chord pages are understood; others (6/9, m11, add11) are skipped and listed as not understood.
What this cannot do
- It does not listen. The front page takes MIDI and microphone input, but names one chord at a time; this finder works from chords you type or tap.
- Only major and minor keys. Modes (Dorian, Mixolydian, ...) are not covered: D, C, G in D Mixolydian is shown as G major chords.
- A best fit from chord names, not a certainty: relative keys share every chord, and the melody decides between them.
- Songs change key. Enter one section at a time if the song modulates, or the borrowed count will climb for every key.
- The capo tip only uses the open shapes C, G, D, A, E, Am, Em, Dm and their sevenths, frets 1 to 7.