Key signature · 3♯
A major key signature and F♯ minor
A major and its relative minor, F♯ minor, share a key signature of three sharps: F♯, C♯ and G♯.
- Sharps3
- WhichF♯ C♯ G♯
- Relative minorF♯ minor
- Home chordA–C♯–E
The key signature
The sharps come right after the clef, on every line of music. In the treble clef: F♯ on the top line, C♯ on the third space and G♯ on the space above the staff. In the bass clef the same sharps appear, in the same order, on the bass staff’s F, C and G.
Each one changes that letter everywhere in the piece, in every octave and on both staves: in A major, every F, C and G is sharp, though no sign is written beside the note.
How to recognise it quickly
Look at the last sharp, the one furthest right: G♯. The major key is a half step above it: A major. For the minor key, go down three half steps from there: F♯ minor.
Sharps always come in the same order, so three sharps are always F♯, C♯ and G♯:
- F♯
- C♯
- G♯
- D♯
- A♯
- E♯
- B♯
Father Charles Goes Down And Ends Battle: the order of sharps, and backwards, the order of flats.
The A major scale
A – B – C♯ – D – E – F♯ – G♯ – A. On the piano that’s three black keys (C♯, F♯ and G♯) and four white (A, B, D and E). Its home chord is A–C♯–E.
More on this key: the A major scale with fingering · the A major chord
F♯ minor, the relative minor
F♯ minor uses the same three sharps, starting from F♯, the sixth note of A major: F♯ – G♯ – A – B – C♯ – D – E – F♯. That’s the natural minor scale. Its home chord is F♯–A–C♯.
Pieces in F♯ minor usually raise the seventh note, E, to E♯ (the harmonic minor), so it leads up to F♯. That E♯ is written as an accidental, not in the key signature: the sharp beside the note is often the quickest clue that a piece is in F♯ minor rather than A major. Pieces also often begin or end on F♯ or its chord.
More on this key: F♯ minor natural minor · F♯ minor harmonic minor · the F♯ minor chord
Music in A major and F♯ minor
Mozart’s Piano Sonata K. 331, which ends with the Turkish March, opens in A major.
Chopin’s Polonaise Op. 44 is in F♯ minor.
On the circle of fifths
One sharp more is E major, a fifth higher; one sharp fewer is D major, a fifth lower. Keys next to each other on the circle of fifths share all but one note, which is why music in A major moves to them most easily.
A minor, with the same home note but a minor scale, has a different key signature: no sharps or flats, the same as C major.
Quiz: name the key signature
Ten key signatures in the treble or bass clef, from all fifteen. Choose the key, or play its home note on the piano below, a MIDI keyboard or your computer keys (any octave).
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Questions
How many sharps are in A major?
Three sharps: F♯, C♯ and G♯. Every F, C and G in the piece is played sharp, in every octave, unless an accidental says otherwise.
What is the relative minor of A major?
F♯ minor. It shares the key signature (three sharps (F♯, C♯ and G♯)) and starts on the sixth note of the A major scale, three half steps below A.
What are the notes of the A major scale?
A, B, C♯, D, E, F♯, G♯, A.
Which key has three sharps?
A major and its relative minor, F♯ minor.
How do you recognise the A major key signature quickly?
Look at the last sharp, the one furthest right: G♯. The major key is a half step above it: A major. For the minor key, go down three half steps from there: F♯ minor.
Keys, one at a time
Pianomi, a free sight-reading app for piano, brings in key signatures one at a time and notices when you play a note as if the key signature weren’t there.