Reference
The circle of fifths
Move clockwise: up a perfect 5th, add a sharp. Counter-clockwise: down a 5th, add a flat. Every key is connected to its neighbours by one note.
Key signatures at a glance
| Major key | Relative minor | Sharps / Flats | Accidentals |
|---|---|---|---|
| C | Am | 0 | — |
| G | Em | 1 ♯ | F♯ |
| D | Bm | 2 ♯ | F♯ C♯ |
| A | F♯m | 3 ♯ | F♯ C♯ G♯ |
| E | C♯m | 4 ♯ | F♯ C♯ G♯ D♯ |
| B | G♯m | 5 ♯ | F♯ C♯ G♯ D♯ A♯ |
| F♯ | D♯m | 6 ♯ | F♯ C♯ G♯ D♯ A♯ E♯ |
| F | Dm | 1 ♭ | B♭ |
| B♭ | Gm | 2 ♭ | B♭ E♭ |
| E♭ | Cm | 3 ♭ | B♭ E♭ A♭ |
| A♭ | Fm | 4 ♭ | B♭ E♭ A♭ D♭ |
| D♭ | B♭m | 5 ♭ | B♭ E♭ A♭ D♭ G♭ |
| G♭ | E♭m | 6 ♭ | B♭ E♭ A♭ D♭ G♭ C♭ |
Why this matters
- Modulation: moving to a neighbouring key (one step around the circle) is the smoothest change because the keys share six of seven notes.
- Chord progressions: the V → I move is a counter-clockwise step on the circle. So is ii → V → I.
- Songwriting: picking three or four adjacent keys gives you a related set of chords for verses, choruses, and bridges.
The order of sharps and flats
Order of sharps (each key adds the next one): F C G D A E B → Father Charles Goes Down And Ends Battle.
Order of flats (reverse): B E A D G C F → Battle Ends And Down Goes Charles's Father.
Trick to find any major key signature: for sharp keys, the key name is one semitone above the last sharp. For flat keys (except F), the key name is the second-to-last flat.