An accidental is a symbol in music notation that raises or lowers a natural note by one or two half steps. The accidental changes the pitch, so that the note is either higher or lower than the original natural note. Accidentals are written in front of the notes, but in text, accidentals are written after the note names.

1. The five accidentals

There are five different accidentals:

A sharp raises a note by a half step. Instead of the original note, you should play the note that is a half step above (on the right of the piano).

A flat lowers a note by a half step. Instead of the original note, you should play the note that is a half step below (on the left of the piano).

Double sharp A double-sharp raises a note by two half steps. Instead of the original note, you should play the note that is two half steps above (on the right of the piano).

A double-flat lowers a note by two half steps. Instead of the original note, you should play the note that is two half steps below (on the left of the piano).

A natural cancels the effect of another accidental.

2. Accidental notes

A note with a sharp () is played a half step above the original note. The seven sharp notes are C (pronounced "C-sharp"), D, E, F, G, A, and B:

Sharp notes

A note with a flat () is played a half step below the original note. The seven flat notes are C (pronounced "C-flat"), D, E, F, G, A, and B:

Flat notes

A note with a double-sharp () is played two half steps above the original note. The seven double-sharp notes are C ("C-double-sharp"), D, E, F, G, A, and B:

Double-sharp notes

A note with a double-flat () is played two half steps below the original note. The seven double-flat notes are C ("C-double-flat"), D, E, F, G, A, and B:

Double-flat notes

3. Enharmonic notes

The black keys on the piano have several names. For example, the black key between C and D can be called C and D. On the piano below, you will find the most common names for the black keys. Click on the piano to listen to the notes:

          Notes with an identical pitch (i.e., notes that fall on the same key on the piano) that have different names and notation are called enharmonic notes. For example, the note C is enharmonic with D, and the note D is enharmonic with E.

          The white keys on the piano have several names too. For example, the key for the note C is also called B. On the piano below, you will find the most common names for the white keys. Click on the piano to listen to the notes:

                Notes with double accidentals ( and ) are very rarely used and therefore not included on the two pianos above. For example, the key for the note G is also called F and A, and the black key for the note G is also called E.

                It is the musical context that determines the name of the note and its notation. In some cases a black key must be notated with a sharp and, in others, a flat. If necessary, read more about this in the texts intervals, chords, scales and keys (coming soon).

                4. Notation of accidentals

                Accidentals are written in front of the notes. An accidental applies:

                • to the note immediately following the accidental
                • to subsequent notes on the same line or in the same space
                • until a barline or a new accidental for the same note.

                In the example below, the sharp in the first bar is canceled by the flat for the following note. The flat is canceled by the barline. The sharp in the second bar does not apply to the note at the top of the staff and is canceled by the natural for the last note:

                The effect of accidentals

                An accidental for a note with a tie applies until the end of the tie if the tie passes a barline. In other words, the accidental applies to both of the tied notes, but not to subsequent notes in the new bar:

                Tied note with accidental

                5. Key signatures

                If a note requires an accidental throughout a piece, the accidental is written in a key signature rather than every time the note occurs. A key signature is a group of sharps or flats at the beginning of the staff immediately after the clef:

                Key signatures

                An accidental in a key signature applies:

                • to all notes with the same note name regardless of their location
                • until the end of the piece of music or a new key signature.

                In the example below, the two sharps in the key signature apply to all versions of the notes F and C. In the first bar, the sharp for F is canceled temporarily by a natural and in the second bar the sharp for C is canceled temporarily by a flat:

                The effect of key signatures

                A key signature may be replaced with another key signature during a piece of music. In the first example below, the three sharps are removed by three naturals, and in the second example the four flats are replaced by two sharps:

                Key signature change

                Accidentals in a key signature are always written in a specific pattern. For more information, read the text about keys (coming soon).

                6. Courtesy accidentals

                Courtesy accidentals are accidentals that are not strictly necessary, but are written to clarify the correct pitch, thus avoiding misunderstandings. Courtesy accidentals are written as normal accidentals, sometimes enclosed by brackets.

                Courtesy accidentals are primarily used in two cases:

                1. When a note with an accidental is repeated in the following bar. The courtesy accidental signifies that the accidental does not apply in the following bar.
                2. When a tie extends an accidental to a new bar where the note is repeated. The courtesy accidental signifies that the accidental does not apply after the tie.

                In the example below, the first courtesy accidental () signifies that the natural does not apply in the subsequent bar, while the other courtesy accidental () signifies that the flat does not apply after the end of the tie:

                Courtesy accidentals