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♯

B♭ (musical note)

B♭ (B-flat; also called si bémol) is the eleventh step of the Western chromatic scale (starting from C). It lies a diatonic semitone above Aand a chromatic semitone below B, thus being enharmonic to A♯, even though in some musical tunings, B♭ will have a different sounding pitch than A♯. B-flat is also enharmonic to C  .

When calculated in equal temperament with a reference of Aabove middle C as 440 Hz, the frequency of the B♭ above middle C is approximately 466.164 Hz. See pitch (music) for a discussion of historical variations in frequency.

While orchestras tune to an A provided by the oboist, wind ensembles usually tune to a B-flat provided by a tuba, horn, or clarinet.

In Germany, Russia, Poland and Scandinavia, this pitch is designated B, with 'H' used to designate the B-natural. Since the 1990s, B-flat is often denoted Bb or "Bess" instead of B in Swedish music textbooks. Natural B is called B by Swedish jazz and pop musicians, but still denoted H in classical music. See B (musical note) for an explanation.

Designation by octave

Scientificdesignation	Helmholtzdesignation	Octave name	Frequency (Hz)
B♭−1	B♭͵͵͵ or ͵͵͵B♭ or BBBB♭	Subsubcontra	14.568
B♭0	B♭͵͵ or ͵͵B♭ or BBB♭	Subcontra	29.135
B♭1	B♭͵ or ͵B♭ or BB♭	Contra	58.270
B♭2	B♭	Great	116.541
B♭3	b♭	Small	233.082
B♭4	b♭′	One-lined	466.164
B♭5	b♭′′	Two-lined	932.328
B♭6	b♭′′′	Three-lined	1864.655
B♭7	b♭′′′′	Four-lined	3729.310
B♭8	b♭′′′′′	Five-lined	7458.620
B♭9	b♭′′′′′′	Six-lined	14917.240
B♭10	b♭′′′′′′′	Seven-lined	29834.481

Scales

Common scales beginning on B♭

• B-flat major: B♭ C D E♭ F G A B♭
• B-flat natural minor: B♭ C D♭E♭ F G♭ A♭ B♭
• B-flat harmonic minor: B♭ C D♭ E♭ F G♭ A B♭
• B-flat melodic minor ascending: B♭ C D♭ E♭ F G A B♭
• B-flat melodic minor descending: B♭ A♭ G♭ F E♭ D♭ C B♭

Diatonic scales

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

Jazz melodic minor

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