C♯ (musical note)

C♯ (C-sharp) is a musical note lying a chromatic semitone above C and a diatonic semitone below D. C-sharp is thus enharmonic to D♭. It is the second semitone in the French solfège and is known there as do dièse. In some European notations, it is known as Cis. In equal temperament it is also enharmonic with B  (Hisis).

When calculated in equal temperament with a reference of Aabove middle C as 440 Hz, the frequency of C♯₄ (the C♯ above middle C) is about 277.18 Hz. See pitch (music) for a discussion of historical variations in frequency.

Designation by octave

Scientificdesignation	Helmholtzdesignation	Octave name	Frequency (Hz)
C♯−1	C♯͵͵͵ or ͵͵͵C♯ or CCCC♯	Subsubcontra	8.662
C♯0	C♯͵͵ or ͵͵C♯ or CCC♯	Subcontra	17.324
C♯1	C♯͵ or ͵C♯ or CC♯	Contra	34.648
C♯2	C♯	Great	69.296
C♯3	c♯	Small	138.591
C♯4	c♯′	One-lined	277.183
C♯5	c♯′′	Two-lined	554.365
C♯6	c♯′′′	Three-lined	1108.731
C♯7	c♯′′′′	Four-lined	2217.461
C♯8	c♯′′′′′	Five-lined	4434.922
C♯9	c♯′′′′′′	Six-lined	8869.844
C♯10	c♯′′′′′′′	Seven-lined	17739.688

Scales

Common scales beginning on C♯

• C♯ major: C♯ D♯ E♯ F♯G♯ A♯ B♯ C♯
• C♯ natural minor: C♯ D♯ E F♯ G♯ A B C♯
• C♯ harmonic minor: C♯ D♯ E F♯ G♯ A B♯ C♯
• C♯ melodic minor Ascending: C♯ D♯ E F♯ G♯ A♯ B♯C♯
• C♯ melodic minor descending: C♯ B A G♯ F♯ E D♯ C♯

Diatonic scales

• C♯ Ionian: C♯ D♯ E♯ F♯G♯ A♯ B♯ C♯
• C♯ Dorian: C♯ D♯ E F♯ G♯A♯ B C♯
• C♯ Phrygian: C♯ D E F♯ G♯A B C♯
• C♯ Lydian: C♯ D♯ E♯ F G♯ A♯ B♯ C♯
• C♯ Mixolydian: C♯ D♯ E♯F♯ G♯ A♯ B C♯
• C♯ Aeolian: C♯ D♯ E F♯ G♯A B C♯
• C♯ Locrian: C♯ D E F♯ G A B C♯

Jazz melodic minor

• C♯ ascending melodic minor: C♯ D♯ E F♯ G♯ A♯ B♯C♯
• C♯ Dorian ♭2: C♯ D E F♯G♯ A♯ B C♯
• C♯ Lydian augmented: C♯ D♯E♯ F  G  A♯ B♯ C♯
• C♯ Lydian dominant: C♯ D♯E♯ F  G♯ A♯ B C♯
• C♯ Mixolydian ♭6: C♯ D♯E♯ F♯ G♯ A B C♯
• C♯ Locrian ♮2: C♯ D♯ E F♯G A B C♯
• C♯ Altered: C♯ D E F G A B C♯