Accidentals and Key Signatures


Accidentals raise or lower the pitch of a note by a half or whole step. There are five kinds of accidentals that are common: flats, sharps, double flats, and double sharps.

Name Image Description
flats Flat lowers a pitch of the note by a half step
sharps Sharp raises a pitch by one half step
double flats Double flat lowers a pitch by a whole step
double sharps Double sharp lowers a pitch by a whole step
naturals Natural cancels a previous accidental

Placement of Accidentals

Accidentals are placed in front of the note that they affect.

Accidentals in front of the notes they affect.

Canceling Double Sharps and Flats

Double sharps and flats occasionally need to be canceled so that a single sharp, flat, or natural can be applied to a note in the same measure. This is generally done by placing a sharp, flat, or natural in front of the note. For example, the second note in the example below is a Bb. The flat doesn't lower the pitch a half step beyond the double flat. The double flat is canceled entirely by the new accidental.

The modern way of canceling double accidentals

Another approach is to use a natural and a single sharp or flat, but this is an older method that is rarely used today.

The old way of canceling double accidentals

What to Call Notes with Accidentals

Notes with accidentals should be named using the note name plus the type of accidental. For example, a B with a flat in front of it is called B flat.

How Long an Accidental Lasts

An accidental only affects any notes in a measure after the accidental occurs.

An accidental in one measure that doesn't carry over to the next measure.

Accidentals on Tied Notes

Notes that are tied from one measure to the next are affected by the accidentals in the previous measure. Any other notes in the measure other than the tied note aren't affected by the accidentals.

How accidentals are affected by tied notes.

Which Notes are Affected by an Accidental

An accidental affects only the pitch in the octave that it precedes. Pitches in a different octave aren't affected. For example, the sharp in the following example only affects Cs on the third space of the staff. Neither of the other Cs are affected.

Accidentals only affect notes in the octave where it appears.

Cautionary Accidentals

Cautionary accidentals (or courtesy accidentals) are a reminder to play the correct pitch when a note that previously had an accidental is found in the next measure. They are often enclosed in parentheses. Cautionary accidentals aren't always used, so be sure to pay close attention to accidentals in all music you play.

Cautionary accidentals after a tied note.

Key Signatures

Key signatures are patterns of sharps or flats found at the beginning of a piece of music. They are used to simplify the use of accidentals in the music. Instead of having to write out each accidental individually, they are included in the key signature and apply to all pitches with that letter name. For example, a Bb in a key signature indicates that all Bs will be flat. Key signatures don't necessarily indicate the key, since a key signature with only F# could indicate G major, E minor, or a mode such as A dorian.

A chart of the key signatures for major keys is given below.

Chart of key signatures.

Sharps and flats in key signatures differ from accidentals that appear within the music in that they affect all pitches no matter which octave. For example, the F# in G major affects all Fs, not just the F on the fifth line of the staff.

Dealing with Accidentals When There is a Key Signature

It is important to remember accidentals in a key signature when dealing with accidentals found within the music itself.