What is a key signature?
A key signature is the set of sharps or flats written at the start of a piece of music. It tells you which notes are sharpened or flattened throughout, so you do not need an accidental every time. The key of G major, for example, has one sharp (F♯), so every F in the piece is played as F♯ unless marked otherwise.
The order of sharps and flats
Sharps and flats always appear in the same order:
- Sharps: F C G D A E B. A memory aid: Father Charles Goes Down And Ends Battle.
- Flats: B E A D G C F, the reverse. Battle Ends And Down Goes Charles' Father.
Reading the key from a signature
- Sharps: look at the last sharp. The major key is a half step above it. Last sharp C♯ means D major.
- Flats: look at the second-to-last flat. That note is the major key. Flats B♭ and E♭ mean B♭ major. One flat is always F major.
- No sharps or flats: C major (or A minor).
Major or minor?
Each signature belongs to two keys: a major key and its relative minor, which starts three half steps lower. Use the music to decide: the chord or note that feels like home is the tonic. Try the relative key finder to see the pair for any key.
The circle of fifths
The circle of fifths arranges the keys so that each step clockwise moves up a fifth and adds one sharp, and each step anticlockwise moves up a fourth and adds one flat. At the bottom of the circle, keys such as F♯ major and G♭ major are the same sounding key written two ways. Neighbouring keys share all but one note, which is why songs modulate easily between them.
Next, see the notes of every key in the scales library, every chord in a key in the chord chart, or practise with Name That Key.
Frequently asked questions
How many sharps does the key of G major have?
One sharp: F♯. Each step clockwise round the circle of fifths adds one sharp, so D has two, A three, E four, B five, F♯ six and C♯ seven.
How do you find the key from the key signature?
For sharps, the last sharp is the leading tone: the major key is a half step above it. For flats, the second-to-last flat names the major key. With one flat, the key is F. With no sharps or flats it is C major (or A minor).
What is the order of sharps and flats?
Sharps are added in the order F C G D A E B, and flats in the reverse order, B E A D G C F.
How do I know if a key signature is major or minor?
A key signature fits both a major key and its relative minor. Look at the music: the chord or note that feels like home, usually the last one, tells you which. Minor keys also often use accidentals such as a raised 7th.
Why do some keys have two names?
F♯ major (6 sharps) and G♭ major (6 flats) sound identical, as do B and C♭, and C♯ and D♭. They are enharmonic keys. Players usually choose whichever has fewer or simpler accidentals.