Key signature · 7♯
C♯ major key signature and A♯ minor
C♯ major and its relative minor, A♯ minor, share a key signature of seven sharps: F♯, C♯, G♯, D♯, A♯, E♯ and B♯. D♭ major sounds exactly the same with five flats.
- Sharps7
- WhichF♯ C♯ G♯ D♯ A♯ E♯ B♯
- Relative minorA♯ minor
- Home chordC♯–E♯–G♯
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, G♯ on the space above the staff, D♯ on the fourth line, A♯ on the second space, E♯ on the top space and B♯ on the middle line. In the bass clef the same sharps appear, in the same order, on the bass staff’s F, C, G, D, A, E and B.
Each one changes that letter everywhere in the piece, in every octave and on both staves: in C♯ major, every F, C, G, D, A, E and B is sharp, though no sign is written beside the note.
How to recognise it quickly
Look at the last sharp, the one furthest right: B♯. The major key is a half step above it: C♯ major. For the minor key, go down three half steps from there: A♯ minor.
Sharps always come in the same order, so seven sharps are always F♯, C♯, G♯, D♯, A♯, E♯ and B♯:
- 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 C♯ major scale
C♯ – D♯ – E♯ – F♯ – G♯ – A♯ – B♯ – C♯. On the piano that’s five black keys (C♯, D♯, F♯, G♯ and A♯) and two white (E♯ and B♯). E♯ and B♯ are played on white keys (E♯ is F and B♯ is C), but spelt that way so every letter appears once. Its home chord is C♯–E♯–G♯.
More on this key: the D♭ major scale with fingering · the D♭ major chord
A♯ minor, the relative minor
A♯ minor uses the same seven sharps, starting from A♯, the sixth note of C♯ major: A♯ – B♯ – C♯ – D♯ – E♯ – F♯ – G♯ – A♯. That’s the natural minor scale. Its home chord is A♯–C♯–E♯.
Pieces in A♯ minor usually raise the seventh note, G♯, to G𝄪 (the harmonic minor), so it leads up to A♯. That G𝄪 is written as an accidental, not in the key signature: a double sharp, since G♯ is already sharp in the key signature is often the quickest clue that a piece is in A♯ minor rather than C♯ major. Pieces also often begin or end on A♯ or its chord.
More on this key: B♭ minor natural minor · B♭ minor harmonic minor · the B♭ minor chord
Music in C♯ major and A♯ minor
Bach wrote a prelude and fugue in every key in The Well-Tempered Clavier; No. 3 of Book 1 is in C♯ major. Most music that sounds in this key is written in D♭ major instead.
A♯ minor is rare: music that sounds in it is nearly always written in B♭ minor (five flats).
On the circle of fifths
One sharp fewer is F♯ major, a fifth lower. Keys next to each other on the circle of fifths share all but one note, which is why music in C♯ major moves to them most easily. At this point the circle wraps round: C♯ major and D♭ major are the same keys on the piano, written with seven sharps or five flats.
C♯ minor, with the same home note but a minor scale, has a different key signature: four sharps, the same as E 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 C♯ major?
Seven sharps: F♯, C♯, G♯, D♯, A♯, E♯ and B♯. Every F, C, G, D, A, E and B in the piece is played sharp, in every octave, unless an accidental says otherwise.
What is the relative minor of C♯ major?
A♯ minor. It shares the key signature (seven sharps (F♯, C♯, G♯, D♯, A♯, E♯ and B♯)) and starts on the sixth note of the C♯ major scale, three half steps below C♯.
What are the notes of the C♯ major scale?
C♯, D♯, E♯, F♯, G♯, A♯, B♯, C♯.
Which key has seven sharps?
C♯ major and its relative minor, A♯ minor. D♭ major (five flats) sounds the same, spelt differently.
How do you recognise the C♯ major key signature quickly?
Look at the last sharp, the one furthest right: B♯. The major key is a half step above it: C♯ major. For the minor key, go down three half steps from there: A♯ 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.