In music, flat means lower in pitch. It may either be used generically, meaning any lowering of pitch, or refer to a particular size: lowering pitch by a chromatic semitone. A flat is the opposite of a sharp () which raises pitch by the same amount that a flat lowers it.

Flat (music)
In UnicodeU+266D MUSIC FLAT SIGN (♭)
Different from
Different fromU+0062 b LATIN SMALL LETTER B

The flat symbol () is used in two ways: It is placed in key signatures to mark lines whose notes are flattened throughout that section of music; it may also be an "accidental" that precedes an individual note and indicates that the note should be lowered temporarily, until the following bar line.

Pitch change

The flat symbol is is a stylised lowercase ‘b’ , derived from Italian be molle for "soft B" and German blatt for "planar, dull". It indicates that the note to which it is applied is played one semitone lower, or in modern tuning exactly 100 cents.[1][2]

In traditional and modern microtonal temperaments the size of sharps or flats (chromatic semitones) is normally smaller than the size of the diatonic semitones found between E and F or B and C. In those tuning systems, the size of the shift made by the symbol usually conforms to the smaller-sized lowering of pitch;[a] however, for some tuning systems it may instead be replaced by a different symbol for raising and lowering pitch, depending on the author's preference and the intricacy of any microtuning involved.[b]

Flats used in key signatures

Order of flats in key signatures
of flats
Major key Flat notes Relative
minor key
0 C major none A minor
1 F major B D minor
2 B major B, E G minor
3 E major B, E, A C minor
4 A major B, E, A, D F minor
5 D major B, E, A, D, G B minor
6 G major B, E, A, D, G, C E minor
7 C major B, E, A, D, G, C, F A minor
The last two rows are shaded because those keys are avoided, in
part because they use inconvenient enharmonic notes, colored red.
In 12 TET the key of C major involves pressing the same keys on
a keyboard as the equivalent B major, which only requires 5 sharps.

The order of flats added onto the key signature is

B, E, A, D, G, C, F.

The corresponding order of keys is off by one:

F, B, E, A, D, G, C.

Starting with no sharps or flats (C major), adding the first flat (B) indicates F major; adding the next (E) indicates B major, and so on, backwards through the circle of fifths.

Some keys (such as C major with seven flats) may be written as an enharmonically equivalent key (B major with five sharps in this case). In rare cases, the flat keys may be extended further:

F → Bdouble flat → Edouble flat → Adouble flat → Ddouble flat → Gdouble flat → Cdouble flat

requiring double flats in the key signature. These are called theoretical key signatures, based on the impracticality of their use, rather than the simpler, equivalent key in 12 TET. This principle applies similarly to the sharp keys.

Key signature example

The staff below shows a key signature with three flats (E major or its relative minor C minor), followed by a note with a flat preceding it: The flat symbol placed on the note indicates that it is a D.

{ \omit Score.TimeSignature \relative c'' { \key es \major des1 } }

In 12 tone equal temperament ( 12 TET )[c] lowering a note's pitch by a semitone results in a note that is enharmonically equivalent to the adjacent named note. In this system, B and A are considered to be equivalent. In most tuning systems, however, this is not the case.

As a temporary accidental

When used as a temporary accidental sign, the flat symbol is placed to the left of the note head.

 { \omit Score.TimeSignature \relative c'' { bes1 } }

Temporary accidentals apply to the note on which they are placed, and to all subsequent similar notes in the same measure and octave. In modern notation they do not apply to notes in other octaves, but this was not always the convention. To cancel an accidental signature later in the same measure and octave, another accidental such as a natural (♮) or a sharp (♯) may be used.

Related symbols

A double flat (double flat) lowers a note by two semitones, or a whole step.

{ \omit Score.TimeSignature \relative c'' { beses1 } }

A quarter-tone flat, half flat, or demiflat indicates the use of quarter tones; it may be marked with various symbols including a flat with a slash (flat stroke) or a reversed flat sign (half flat). A three-quarter-tone flat, flat and a half or sesquiflat, is represented by a demiflat and a whole flat (three quarter flat).

The symbols -, , flat stroke, among others, represent comma flat or eighth-tone flat, or a quarter of a flat (not to be confused with the larger quarter tone).[d]

{ \omit Score.TimeSignature \relative c'' { ceh1 deseh } }

Although very rarely used, a triple flat (triple flat) can sometimes be found.[3] It lowers a note three semitones, or a whole tone and a semitone.

\omit Score.TimeSignature \relative c'' {
  \tweak Accidental.stencil #ly:text-interface::print \tweak Accidental.text \markup { \concat { \flat \doubleflat ))beses1
} }

The symbol of a quadruple flat,[e] or beyond, could be used but would be extremely rare in ordinary temperament.[4]

\omit Score.TimeSignature \relative c'' {
  \tweak Accidental.stencil #ly:text-interface::print \tweak Accidental.text \markup { \concat { \doubleflat \doubleflat ))beses1
} }


The Unicode character ♭ (U+266D) can be found in the block Miscellaneous Symbols; its HTML entity is ♭ . Other assigned flat signs are as follows:

Other notation and usage


  1. ^ For example: In quarter-comma meantone a flat always lowers a note's pitch by 76.05 cents ; in just intonation a flat normally lowers a note's pitch by 70.57 cents. Compare those to the somewhat excessive 100 cents used in 12 TET. In Pythagorean tuning the size of a flat is a whopping 113.7 cents. In well temperaments a flat is two or more different sizes, depending on the temperament and where the starting, unflattened note sits on the circle of fifths.
  2. ^ a b For example, in 53 TET sharps and flats have two or three different sub-levels, and notation for flattening notes varies, but usually involves several different symbols; one of the sets of 53 TET flat symbols is (67.9 cents), half flat (45.3 cents), and (22.6 cents), used both separately and in combinations.
  3. ^ 12 TET is the predominant system of tuning in Western music.
  4. ^ The size of the lowering of pitch by a "comma" varies, depending on the tuning system; it is normally 21 + 1 / 2 cents but can vary between 20–25 cents.[b]
  5. ^ A quadruple flat ( double flatdouble flat ) lowers a note by four semitones or two whole tones in standard tuning.

See also


  1. ^ Benward & Saker (2003). Music in Theory and Practice. Vol. 1 (7th ed.). McGraw-Hill. p. 6. Flat () lowers the pitch a half step.
  2. ^ Flat. Glossary. Naxos Records. Archived from the original on 2021-07-15. Retrieved 2015-02-06.
  3. ^ Byrd, Donald (October 2018). "Extremes of conventional music notation". Bloomington, IN: Indiana University.
  4. ^ Wen, Eric (2011). "E-quadruple flat: Tovey's whimsy". Zeitschrift der Gesellschaft für Musiktheorie (in German). 8 (1): 77–89. doi:10.31751/612.
  5. ^ Fonville, J. (Summer 1991). "Ben Johnston's extended just intonation – a guide for interpreters". Perspectives of New Music. 29 (2): 106–137. ... the  25 / 24  ratio is the sharp () ratio ... this raises a note approximately 70.6 cents.(p 109)