Tools
Key finder
Find the key of a song from its chords, or of a melody from its notes. The tool scores all twenty-four keys against what you enter, names the most likely one with its runners-up, and shows what that key holds: its signature, its chords, its relative, and your own material read back as roman numerals or scale degrees.
The key will appear here.
How key detection works
A key is a home note — the tonic — and the family of notes and chords built around it. Most songs settle on that home at the start and at the end, so the first and last chords are the strongest clue; a tool cannot hear where a phrase rests, but it can count where the music keeps returning.
The second clue is the dominant, the chord a fifth above the tonic. A dominant that resolves onto the tonic — G to C, or G7 to Cmaj7 — is a cadence, and a cadence names a key more surely than any single chord. That is why Dm7–G7–Cmaj7 reads as C major and not as D minor, even though it opens on a D minor chord.
Every major key shares its notes with a minor key three semitones lower, its relative minor. C major and A minor contain the same seven notes and the same seven chords, so a set of notes alone cannot tell them apart. The tool looks at which of the two tonics is present, which chord the music starts on, and — for a minor key — whether the raised leading note is there: a G♯ among A, B, C, D, E and F is what turns the natural minor scale into the harmonic minor a real A minor piece uses.
Chords are scored by how well every note of the chord sits in each key’s scale, then the bonuses above are added; for notes, each pitch that belongs to the key counts for it and each pitch outside it counts against. The best key is shown as “likely” when it leads clearly and as “possibly” when a runner-up is close, and you can choose any runner-up to read your material in that key instead.
A worked example
C G Am F→C major
I–V–vi–IV · A minor: bIII–bVII–i–bVI
The most common loop in pop. Every chord belongs to C major, the progression starts on C, and G — the dominant — is there. A minor holds the same four chords, but starting on C rather than on Am is what settles it. Read in C major the chords are I–V–vi–IV; read in A minor they would be III–VII–i–VI, a far less usual way to write the same thing.
E F♯ G A B C D→E minor · G major
Seven notes and no clue but the first. These are exactly the notes of G major and of E natural minor, so the tool leans on the note you entered first and says “possibly E minor”. Add a D♯ — the leading note of E minor — and the doubt is gone: D♯ belongs to E minor and not to G major.
All 24 keys
Every major and minor key with its signature, its seven diatonic chords and its relative. The minor keys show the chords of the natural minor scale; in practice the V of a minor key is usually played major (E or E7 in A minor), borrowing the raised leading note from the harmonic minor.
| Key | Signature | Diatonic chords | Relative |
|---|---|---|---|
| C major | — | A minor | |
| G major | 1♯ | E minor | |
| D major | 2♯ | B minor | |
| A major | 3♯ | F♯ minor | |
| E major | 4♯ | C♯ minor | |
| B major | 5♯ | G♯ minor | |
| F♯ major | 6♯ | D♯ minor | |
| D♭ major | 5♭ | B♭ minor | |
| A♭ major | 4♭ | F minor | |
| E♭ major | 3♭ | C minor | |
| B♭ major | 2♭ | G minor | |
| F major | 1♭ | D minor | |
| A minor | — | C major | |
| E minor | 1♯ | G major | |
| B minor | 2♯ | D major | |
| F♯ minor | 3♯ | A major | |
| C♯ minor | 4♯ | E major | |
| G♯ minor | 5♯ | B major | |
| E♭ minor | 6♭ | G♭ major | |
| B♭ minor | 5♭ | D♭ major | |
| F minor | 4♭ | A♭ major | |
| C minor | 3♭ | E♭ major | |
| G minor | 2♭ | B♭ major | |
| D minor | 1♭ | F major |
Questions about keys
- How do I know if a song is major or minor?
- Listen for where it rests. If the chord that feels like home is major — and the tune keeps landing on it — the song is in the major key; if that home chord is minor, the song is in the relative minor, whatever the key signature says. On paper, a minor song usually shows the raised seventh of its key as an accidental (G♯ in A minor), and its chords start and end on the minor tonic.
- What key has two sharps?
- D major, and its relative B minor. The sharps are F♯ and C♯. One sharp is G major or E minor; three sharps is A major or F♯ minor; each further sharp moves the key up a fifth. The table on this page lists all of them.
- What key has three flats?
- E♭ major, and its relative C minor. The flats are B♭, E♭ and A♭. One flat is F major or D minor, two flats B♭ major or G minor, four flats A♭ major or F minor.
- Can a song use chords outside its key?
- Constantly. A dominant borrowed from another key (D7 in C major, leading to G), a chord from the parallel minor (Fm or B♭ in C major) or a chromatic passing chord are all normal, and none of them changes the key. The tool scores every chord and lets the majority decide, so one borrowed chord will not move the result; the runners-up show the keys it might have come from.
- What is the difference between a key and a scale?
- A scale is a set of notes in order; a key is the way a piece uses one of those sets, with a tonic that sounds like home and chords built on each degree. C major the scale is seven notes; C major the key is those notes plus the habit of resolving to C. Each key in the tool links to the page of its scale.
- How do I find the key of a melody without chords?
- Switch the tool to notes and tap the melody’s notes on the keyboard, or type them. The note the melody keeps returning to and ends on is almost always the tonic; enter it first, since the tool gives the first note a little extra weight. A raised seventh (such as G♯ among the notes of A minor) points to the minor key.
- What is the relative minor, and why does the tool sometimes offer both keys?
- Every major key has a minor key that uses exactly the same notes and the same key signature, starting three semitones lower: C major and A minor, G major and E minor. Because the notes are identical, they can only be told apart by how the music treats them — which chord it starts and ends on, and whether the minor key’s raised leading note appears. When neither clue is present, the tool says “possibly” and names the other key, and you can select it to read your chords that way.
- Why does the tool say “possibly” instead of giving one answer?
- Because a short or ambiguous progression genuinely fits more than one key. Two chords fit half a dozen keys; a full set of seven notes fits a major key and its relative minor equally. Rather than pretend, the tool shows how far ahead its best guess is and lists the runners-up, so you can decide by ear.