Flat (music)


In music, flat means "lower in pitch". Flat is the opposite of sharp, which is a raising of pitch. In musical notation, flat means "lower in pitch by one semitone ", notated using the symbol which is derived from a stylised lowercase 'b'. For instance, the music below has a key signature with three flats and the note, D, has a flat accidental.

The Unicode character ♭ can be found in the block Miscellaneous Symbols; its HTML entity is ♭.
Under twelve-tone equal temperament, D for instance is enharmonically equivalent to C, and G is equivalent to F. In any other tuning system, such enharmonic equivalences in general do not exist. To allow extended just intonation, composer Ben Johnston uses a sharp as an accidental to indicate a note is raised 70.6 cents, and a flat to indicate a note is lowered 70.6 cents.
In intonation, flat can also mean "slightly lower in pitch". If two simultaneous notes are slightly out-of-tune, the lower-pitched one is "flat" with respect to the other. Furthermore, the verb flatten means to lower the pitch of a note, typically by a small musical interval.

Key signatures

Flats are used in the key signatures of
  1. F major / D minor
  2. B major / G minor
  3. E major / C minor
  4. A major / F minor
  5. D major / B minor
  6. G major / E minor
  7. C major / A minor
The order of flats in the key signatures of music notation, following the circle of fifths, is B, E, A, D, G, C and F.

Related symbols

Double flats also exist, which look like and lower a note by two semitones, or a whole step. The Unicode character ? in the Musical Symbols block represents the double-flat sign. Historically, in order to raise a double flat to a simple flat, it was required to use the notation. In modern scores it is acceptable to simply denote this with a single flat.

A quarter-tone flat or half flat, indicating the use of quarter tones, may be marked with various symbols including a flat with a slash or a reversed flat sign. A three-quarter-tone flat, flat and a half or sesquiflat, is represented by a half flat and a regular flat.
Although very uncommon, a triple flat can sometimes be found. It lowers a note three semitones.