C♯ (musical note)

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "C♯" musical note – news · newspapers · books · scholar · JSTOR (June 2025) (Learn how and when to remove this message)

C♯ (C-sharp) is a musical note lying a chromatic semitone above C and a diatonic semitone below D; it is the second semitone of the solfège. 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 (B-double sharp/Hisis).

When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of C♯₄ (the C♯ above middle C) is about 277.183 Hz.^[1] See pitch (music) for a discussion of historical variations in frequency.

Frequency

Historically, concert pitch has varied. For an instrument in equal temperament tuned to the A440 pitch standard widely adopted in 1939, middle C#, the note above middle C has a frequency around 277.18 Hz^[2] (for other notes see piano key frequencies). Scientific pitch was originally proposed in 1713 by French physicist Joseph Sauveur and based on the numerically convenient frequency of 256 Hz for middle C, all C's being powers of two, making the pitch of C# 276.8067 Hz. After the A440 pitch standard was adopted by musicians, the Acoustical Society of America published new frequency tables for scientific use. A movement to restore the older A435 standard has used the banners "Verdi tuning", "philosophical pitch" or the easily confused scientific pitch.

Designation by octave

Graphic representation

Scales

References

See also

• Piano key frequencies
• Root (chord)