|Relative key||A♯ minor
enharmonic: B♭ minor
|Parallel key||C♯ minor|
|Dominant key||G♯ major
enharmonic: A♭ major
|C♯, D♯, E♯, F♯, G♯, A♯, B♯, C♯|
Its relative minor is A♯ minor, usually relaced by B♭ minor, since B♭ minor has just only five flats while A-sharp minor has seven sharps, making it rare to be used in musical arrangement and its parallel minor is C♯ minor.
A harp tuned to C-sharp major has all its pedals in the bottom position. Because all the strings are then pinched and shortened, this is the least resonant key for the instrument.
Although most composers prefer to use the enharmonic equivalent D-flat major because it has just five flats as opposed to the seven sharps of C-sharp major, Johann Sebastian Bach chose C-sharp major for Prelude and Fugue No. 3 in both books of the Well-Tempered Clavier. In Hungarian Rhapsody No. 6, Franz Liszt takes the unusual step of changing key from D-flat major to C-sharp major near the beginning of the piece. Maurice Ravel selected C-sharp major as the tonic key of Ondine from his piano suite Gaspard de la nuit. Erich Wolfgang Korngold composed his Piano Concerto for the Left Hand, Op. 17, in the key of C-sharp major.
Louis Vierne used C-sharp major for the "Dona Nobis Pacem" of the Agnus Dei of his Messe Solennelle in C sharp minor.
|Diatonic scales and keys|
|The table indicates the number of sharps or flats in each scale. Minor scales are written in lower case.|