C (C-sharp) is a musical note lying a

chromatic semitone In modern Western tonal music theory an augmented unison or augmented prime is the interval between two notes on the same staff position, or denoted by the same note letter, whose alterations cause them, in ordinary equal temperament, to be one ...

above C and a

diatonic semitone A semitone, also called a half step or a half tone, is the smallest interval (music), musical interval commonly used in Western tonal music, and it is considered the most Consonance and dissonance#Dissonance, dissonant when sounded harmonically ...

below D; it is the second

semitone A semitone, also called a half step or a half tone, is the smallest musical interval commonly used in Western tonal music, and it is considered the most dissonant when sounded harmonically. It is defined as the interval between two adjacent no ...

of the

solfège In music, solfège (, ) or solfeggio (; ), also called sol-fa, solfa, solfeo, among many names, is a music education method used to teach aural skills, pitch and sight-reading of Western music. Solfège is a form of solmization, though the tw ...

. C-sharp is thus

enharmonic In modern musical notation and tuning, an enharmonic equivalent is a note, interval, or key signature that is equivalent to some other note, interval, or key signature but "spelled", or named differently. The enharmonic spelling of a writte ...

to D. It is the second semitone in the French

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 (B-double sharp/Hisis). When calculated in

equal temperament An equal temperament is a musical temperament or tuning system, which approximates just intervals by dividing an octave (or other interval) into equal steps. This means the ratio of the frequencies of any adjacent pair of notes is the same, ...

with a reference of A above

middle C C or Do is the first note and semitone of the C major scale, the third note of the A minor scale (the relative minor of C major), and the fourth note (G, A, B, C) of the Guidonian hand, commonly pitched around 261.63 Hz. The actual fr ...

as 440 Hz, the

frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...

of C₄ (the C above middle C) is about 277.183 Hz. See

pitch (music) Pitch is a perceptual property of sounds that allows their ordering on a frequency-related scale, or more commonly, pitch is the quality that makes it possible to judge sounds as "higher" and "lower" in the sense associated with musical melodi ...

for a discussion of historical variations in frequency.

Designation by octave

Scales

Common scales beginning on C

C major C major (or the key of C) is a major scale based on C, consisting of the pitches C, D, E, F, G, A, and B. C major is one of the most common keys used in music. Its key signature has no flats or sharps. Its relative minor is A minor and ...

: 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 In music theory, the minor scale is three scale patterns – the natural minor scale (or Aeolian mode), the harmonic minor scale, and the melodic minor scale (ascending or descending) – rather than just two as with the major scale, which al ...

ascending: C D E F G A B C * C melodic minor descending: C B A G F E D C

Diatonic scale In music theory, a diatonic scale is any heptatonic scale that includes five whole steps (whole tones) and two half steps (semitones) in each octave, in which the two half steps are separated from each other by either two or three whole st ...
s

* 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 In music, the acoustic scale, overtone scale, Lydian dominant scale, Lydian 7 scale, or the Pontikonisian Scale is a seven-note synthetic scale. : This differs from the major scale in having an augmented fourth and a minor seventh scale degre ...

: 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

Designation by octave

Scales

Common scales beginning on C

Diatonic scale In music theory, a diatonic scale is any heptatonic scale that includes five whole steps (whole tones) and two half steps (semitones) in each octave, in which the two half steps are separated from each other by either two or three whole st ...s

Jazz melodic minor

See also

Diatonic scale In music theory, a diatonic scale is any heptatonic scale that includes five whole steps (whole tones) and two half steps (semitones) in each octave, in which the two half steps are separated from each other by either two or three whole st ...
s