Double flat
The double flat lowers a note by two semitones, so by a whole tone. C becomes C double flat, which sounds like B♭ on the piano. You find it mainly in chromatic lines and in chords whose spelling is meant to show their function.
- Effect
- lowers by 2 semitones (a whole tone)
- Name
- “double flat” added (C double flat, D double flat, B double flat …)
- Example
- C double flat sounds like B♭
- Typical in
- chromatic lines, late Romanticism
- Counterpart
- double sharp
Two semitones lower
On the page Notation symbols it says: the double flat lowers the note by a whole tone. C becomes C double flat, which sounds like B♭, E becomes E double flat, which sounds like D. On the page Name the Note it is one of the possibilities for forming all the notes of notation from seven natural notes: every natural note can be lowered by a semitone with a flat, and even by two with a double flat.
| Natural note | With double flat | Sounds like |
|---|---|---|
| C | C double flat | B♭ |
| D | D double flat | C |
| E | E double flat | D |
| F | F double flat | E♭ |
| G | G double flat | F |
| A | A double flat | G |
| B | B double flat | A |
The double flat is, according to the page, frequent in late Romanticism, in composers such as Wagner, Strauss and Mahler, who go chromatically complex to the limits of the tonal system. Like the double sharp it occurs mainly in chromatic lines or in functional harmony, where the correct enharmonic spelling makes musical relationships clear.
An example: B double flat in the diminished seventh chord
The article The diminished seventh gives a vivid example: the chord consists of four notes, each a minor third apart, so from C: C, E♭, G♭ and B double flat. In practice the top note is usually written as A, because that is easier to read. B double flat is the spelling that reproduces the stacking of thirds correctly: C–E♭–G♭–B double flat are four letters at third distances.
The page on enharmonics shows how to link the two names: the equivalent of F♯ is G♭, but the equivalent of F double sharp is G, and the equivalent of C double flat is B♭. Such cases seem contrived, but follow inevitably from the system and occur in real literature.
Double flat and the German note names
In German the note B natural is called H, and the note with a flat in front, B♭, is called B. If you lower H twice, you get “heses”, which sounds like A. In the English-speaking world, where the note is called B, “heses” corresponds to B double flat. The page Name the Note points out that in English-speaking countries B is written instead of H.
Common mistakes
- Confusing C double flat and C♭: C♭ has one flat, C double flat two. C♭ sounds like B, C double flat like B♭.
- Confusing B double flat and B♭: B double flat sounds like A, B♭ on the other hand like a lowered B.
- Taking the double flat for superfluous: It is the only way to write certain stackings of thirds correctly.
Continue on Maikstrings
Related terms
Double sharpNatural signAccidental (in the bar)Enharmonic equivalenceDiminished seventh chordAccidentalSharp
Editor: Maik Krohm · reviewed on 3 October 2026
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