The twelve keys
A reference card. You don't memorise this — you come back to it.
Twelve keys, fifteen signatures
There are 12 notes to build a major key on. But there are 15 possible written key signatures, because three keys have two legal spellings:
| Sharp spelling | = Flat spelling |
|---|---|
| B major (5 sharps) | C♭ major (7 flats) |
| F♯ major (6 sharps) | G♭ major (6 flats) |
| C♯ major (7 sharps) | D♭ major (5 flats) |
Same piano keys, same violin fingers — different names on the page. So "12 pitch classes" does not mean "12 key signatures." A composer picks the spelling with fewer accidentals (D♭'s five flats beat C♯'s seven sharps), or the one that fits where the music is heading.
The practical spellings
| Key | Sharps / flats | Scale |
|---|---|---|
| C | — | C D E F G A B C |
| G | 1♯ | G A B C D E F♯ G |
| D | 2♯ | D E F♯ G A B C♯ D |
| A | 3♯ | A B C♯ D E F♯ G♯ A |
| E | 4♯ | E F♯ G♯ A B C♯ D♯ E |
| B | 5♯ | B C♯ D♯ E F♯ G♯ A♯ B |
| F♯ | 6♯ | F♯ G♯ A♯ B C♯ D♯ E♯ F♯ |
| F | 1♭ | F G A B♭ C D E F |
| B♭ | 2♭ | B♭ C D E♭ F G A B♭ |
| E♭ | 3♭ | E♭ F G A♭ B♭ C D E♭ |
| A♭ | 4♭ | A♭ B♭ C D♭ E♭ F G A♭ |
| D♭ | 5♭ | D♭ E♭ F G♭ A♭ B♭ C D♭ |
| G♭ | 6♭ | G♭ A♭ B♭ C♭ D♭ E♭ F G♭ |
The ones you'll actually play are at the top: C, G, D, A major this stage (plus E minor), and F and B♭ as your fingering grows.
Double sharps and double flats
A double sharp (an x-shaped sign) raises a note two half steps; a double flat (♭♭) lowers it two. They never sit in a standard key signature — but they appear as accidentals, most often as a raised leading tone inside a sharp minor key. G♯ minor's leading tone is written F-double-sharp (F♯ raised again — it sounds like G natural, but it's spelled as a raised 7th degree, and the 7th degree of G♯ is some kind of F).
Where you land
Read a signature, name the key with the tricks from Key signatures in full, check whether it's the major or the relative minor, and know that a strange-looking spelling (C♭, F-double-sharp) is just a familiar sound wearing an unfamiliar name.