Sharp (music)

In music, sharp – eqv. dièse or diesis – means higher in pitch. The sharp symbol, ♯, indicates that the note to which the symbol is applied is played one chromatic semitone higher. The opposite of sharp is flat, indicating a lowering of pitch. The symbol derives from a square form of the letter b.

Examples

The sharp symbol is used in key signatures or as an accidental applied to a single note. Below is a staff with a key signature containing three sharps and a sharp symbol placed on the note, indicating that it is an A instead of an A.

In twelve-tone equal temperament tuning, raising a note's pitch by a semitone results in a note that is enharmonically equivalent to another named note. For example, E and F would be equivalent. This is not the case in most non-standard tuning systems.

Variants

A double sharp is indicated by the symbol and raises a note by two chromatic semitones. Double sharps were sometimes written, or.
A or demisharp raises a note by approximately a quarter tone. A sharp-and-a-half, three-quarter-tone sharp or sesquisharp raises a note by three quarter tones.
A triple sharp is extremely rare. It raises a note by three chromatic semitones. The B below would be enharmonic with D natural.
While this system allows for higher multiples of sharps, triple sharps are the practical limit, and there are only a few examples in the literature. In other tuning systems, such as 53 equal temperament, quadruple sharps or beyond may be required. A quadruple sharp would be indicated by the symbol.

Key signature

In a key signature, sharps or flats are placed to the right of the clef. The pitches indicated apply in every measure and octave.

Number of sharps	Major key	Sharp notes	Minor key
0	C major	–	A minor
1	G major	F♯	E minor
2	D major	F♯, C♯	B minor
3	A major	F♯, C♯, G♯	F minor
4	E major	F♯, C♯, G♯, D♯	C minor
5	B major	F♯, C♯, G♯, D♯, A♯	G minor
6	F♯ major	F♯, C♯, G♯, D♯, A♯, E♯	D minor
7	C♯ major	F♯, C♯, G♯, D♯, A♯, E♯, B♯	A minor

The order of sharps in key signatures is F♯, C♯, G♯, D♯, A♯, E♯, B♯. Starting with no sharps or flats, adding the first sharp indicates G major, adding the next indicates D major, and so on through the circle of fifths.
Some keys may be written as an enharmonically equivalent key. In the standard tuning system of 12-tone equal temperament, the key of C major, with seven sharps, may be written as D major, with five flats. In rare cases the sharp keys may be extended further, into key signatures requiring a double sharp.

Accidental

When used as an accidental, the sharp sign applies to the note on which it is placed, and to subsequent similar notes in the same measure and octave. In modern notation accidentals do not apply to notes in other octaves, but this was not always the convention.
As with all accidentals, a sharp can be cancelled on a subsequent similar note in the same measure by using a flat or a natural.

Unicode

In Unicode, assigned sharp signs are as follows:

Other notation and usage
The sharp symbol resembles the number sign, with two intersecting sets of parallel double lines. While the number sign may have a pair of horizontal lines, the sharp sign has a pair of slanted lines that rise from left to right to avoid obscuring the staff lines. The other set of parallel lines are vertical in the sharp sign, while the number sign may have slanted lines instead. It is also etymologically independent from the number sign. Likewise, while the double-sharp sign resembles a lower-case letter "x", it needs to be typographically distinct.
Historically, lowering a double sharp to a single sharp could be notated using a natural sign and sharp sign or vice-versa, but modern notation often uses the sharp sign alone. The same principle applies when canceling a triple sharp or beyond. The combination ♮♯ can be also written when changing a flat to a sharp.

In environments where the symbol is not supported a double sharp can be written using two single sharp signs, hash signs or a lower-case letter x. Likewise, a triple sharp can be written as ♯♯♯.
To allow extended just intonation, composer Ben Johnston uses a sharp to indicate a note is raised 70.6 cents.