Key Signatures
A key signature is the group of sharps or flats just after the clef. To name the key, count them. With sharps, the key is a half step above the last sharp; with flats, it's the second-to-last flat (and one flat is F major). No sharps or flats is C major, or its relative minor, A minor.
What a key signature does
A key signature tells you which notes are sharp or flat all the way through the music, so they don’t need a sign every time. A sharp on the F line means every F is F sharp: on that line, in the bottom space, in every octave. It lasts until the key signature changes.
A sharp, flat or natural written next to a single note (an accidental) overrides the key signature, but only until the next bar line.
How to read a key signature
1. Count the sharps or flats. None means C major (or A minor).
2. Name the major key:
- Sharps: the key is a half step above the last sharp. Three sharps end on G♯, and a half step above G♯ is A: A major.
- Flats: the key is the second-to-last flat. Three flats are B♭, E♭, A♭; the second-to-last is E♭: E♭ major. One flat has no second-to-last, so learn it by heart: one flat is F major.
3. Decide whether it’s major or minor. Every key signature fits a major key and its relative minor. Look at the note the music ends on (and often starts on): that’s usually the home note. One sharp and ending on G is G major; ending on E, it’s E minor.
The order of sharps and flats
Sharps and flats are always written in the same order, so you never need to read them one by one.
| Order | |
|---|---|
| Sharps | F♯ C♯ G♯ D♯ A♯ E♯ B♯ |
| Flats | B♭ E♭ A♭ D♭ G♭ C♭ F♭ |
The flats are the sharps backwards. A saying that covers both: Father Charles Goes Down And Ends Battle for sharps, and Battle Ends And Down Goes Charles’ Father for flats.
A key with two sharps always has F♯ and C♯; a key with three flats always has B♭, E♭ and A♭. The circle of fifths shows why: each step round it adds the next sign in the order.
Major and minor key signature chart
| Sharps or flats | Major key | Minor key | Signs |
|---|---|---|---|
| none | C major | A minor | — |
| 1 sharp | G major | E minor | F♯ |
| 2 sharps | D major | B minor | F♯ C♯ |
| 3 sharps | A major | F♯ minor | F♯ C♯ G♯ |
| 4 sharps | E major | C♯ minor | F♯ C♯ G♯ D♯ |
| 5 sharps | B major | G♯ minor | F♯ C♯ G♯ D♯ A♯ |
| 6 sharps | F♯ major | D♯ minor | F♯ C♯ G♯ D♯ A♯ E♯ |
| 7 sharps | C♯ major | A♯ minor | all seven |
| 1 flat | F major | D minor | B♭ |
| 2 flats | B♭ major | G minor | B♭ E♭ |
| 3 flats | E♭ major | C minor | B♭ E♭ A♭ |
| 4 flats | A♭ major | F minor | B♭ E♭ A♭ D♭ |
| 5 flats | D♭ major | B♭ minor | B♭ E♭ A♭ D♭ G♭ |
| 6 flats | G♭ major | E♭ minor | B♭ E♭ A♭ D♭ G♭ C♭ |
| 7 flats | C♭ major | A♭ minor | all seven |
Three pairs sound the same and are just spelled differently: B and C♭ major, F♯ and G♭ major, C♯ and D♭ major. Most music uses the spelling with fewer signs.
Where the signs sit on the staff
On the treble staff, the sharps zigzag down and up from the top line: F♯ on the top line, C♯ in the third space, G♯ just above the staff, then D♯, A♯, E♯ and B♯ in a set pattern. The flats start on the middle line: B♭, then E♭ in the top space, A♭ in the second space, and so on.
On the bass staff the pattern is the same shape, one line or space lower: the first sharp is on the bass staff’s F line (the fourth line up), the first flat on its B line (the second line up).
Practice reading key signatures
Trebly’s key signatures lesson has you name keys from their signatures on both staves, read notes the key signature changes, and read a song in G. The circle of fifths lesson goes on to three sharps and three flats.