Key Signatures
You can already write major scales with sharps and flats. When a piece uses one major scale, it is in that key, and the scale's sharps or flats can be written once at the start of every line instead of in front of every note.
From scales to keys
A key takes its name from the starting note of its scale: a piece built from the G major scale is in G major. Every major scale follows the same T–T–S–T–T–T–S pattern, but not every key needs the same accidentals. G major needs one sharp, F♯, to keep that pattern.
Sort the major scales that use sharps from fewest to most, and the keys fall into a fixed order:
| Key | Sharps | Which sharps |
|---|---|---|
| C major | 0 | none |
| G major | 1 | F♯ |
| D major | 2 | F♯, C♯ |
| A major | 3 | F♯, C♯, G♯ |
| E major | 4 | F♯, C♯, G♯, D♯ |
| B major | 5 | F♯, C♯, G♯, D♯, A♯ |
| F♯ major | 6 | F♯, C♯, G♯, D♯, A♯, E♯ |
| C♯ major | 7 | F♯, C♯, G♯, D♯, A♯, E♯, B♯ |
The order of sharps
Look down the last column of the table: each key keeps the sharps of the key before it and adds one more. So two sharps are always F♯ and C♯, three sharps add G♯, and so on. Read the new sharps in turn and you have the order of sharps.
Order of sharps
- FFather
- CCharles
- GGoes
- DDown
- AAnd
- EEnds
- BBattles
The order of flats
Flat keys follow the circle backwards: F major has one flat, B♭ major two, and so on to C♭ major with seven. The flats appear in the exact reverse order of the sharps.
Order of flats
- BBattles
- EEnd
- AAnd
- DDown
- GGoes
- CCharles’
- FFather
| Key | Flats | Which flats |
|---|---|---|
| F major | 1 | B♭ |
| B♭ major | 2 | B♭, E♭ |
| E♭ major | 3 | B♭, E♭, A♭ |
| A♭ major | 4 | B♭, E♭, A♭, D♭ |
| D♭ major | 5 | B♭, E♭, A♭, D♭, G♭ |
| G♭ major | 6 | B♭, E♭, A♭, D♭, G♭, C♭ |
| C♭ major | 7 | B♭, E♭, A♭, D♭, G♭, C♭, F♭ |
Writing the key signature
Instead of writing the accidentals in front of each note, composers collect them and write them once at the beginning of the music, after the clef. That group of sharps or flats is the key signature. It tells you every sharp or flat to play, for that letter in every octave, and every line of music in the key starts with it.
Before
E major with accidentals
After
E major with a key signature
Where each sharp sits
Each sharp has its own place on the staff, and it never changes. In the treble clef, F♯ starts on the top line and the rest zig-zag down and up. In the bass clef the pattern is the same shape, one space lower.
Treble clef
Sharps start on the top line
Bass clef
Same zig-zag, one space lower
| Sharp | Treble clef | Bass clef |
|---|---|---|
| F♯ | top line | fourth line |
| C♯ | third space | second space |
| G♯ | space above the staff | top space |
| D♯ | fourth line | middle line |
| A♯ | second space | first space |
| E♯ | top space | third space |
| B♯ | middle line | second line |
Where each flat sits
The flats have fixed places too. In the treble clef, B♭ starts on the middle line, then E♭ goes up to the top space and A♭ down to the second space, swinging back and forth. In the bass clef the pattern again sits one space lower.
Treble clef
Flats start on the middle line
Bass clef
Same swing, one space lower
| Flat | Treble clef | Bass clef |
|---|---|---|
| B♭ | middle line | second line |
| E♭ | top space | third space |
| A♭ | second space | first space |
| D♭ | fourth line | middle line |
| G♭ | second line | bottom line |
| C♭ | third space | second space |
| F♭ | first space | space below the staff |
Write it yourself
Practise the way the textbook does: first copy the full orders of sharps and flats in both clefs, then write key signatures from one sign up to seven.
Draw the clef
The clef decides where every sign goes, so it always comes first.Count the signs
Use the tables to find how many sharps or flats the key has.Write them in order
Sharps F C G D A E B, flats B E A D G C F. Stop when you have enough.Place each one exactly
Each sign sits on its own line or space, centred on it, the same in every key.Check the shape
Sharps and flats zig-zag; if two neighbours sit far apart or out of line, one is in the wrong octave.Repeat on every line
Every line of music in the key starts with the same signature.
Mastery Checkpoint
- Say the order of sharps and the order of flats, forwards and backwards.
- Name how many sharps G, D, A, E, B, F♯ and C♯ major have, and how many flats F, B♭, E♭, A♭, D♭, G♭ and C♭ major have.
- Write all seven sharps and all seven flats in the treble clef and in the bass clef, each on its own line or space.
- Explain why E major can be written with four accidentals or with a four-sharp key signature, and why the music sounds the same.
In the next lesson, you will learn two quick methods for naming the key of any signature, and for working back from a key to its signature.