B♭ (musical note)

B♭ (B-flat), or, in some European countries, B, is the eleventh step of the Western chromatic scale (starting from C). It lies a diatonic semitone above A and a chromatic semitone below B, thus being enharmonic to A, even though in some musical tunings, B♭ will have a different sounding pitch than A♯. B-flat is also enharmonic to C (C-double flat).

When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of the B♭ above middle C is approximately 466.164 Hz. See musical pitch for a discussion of historical variations in frequency.

While orchestras tune to an A provided by the oboist, wind ensembles usually tune to a B-flat.

In Germany, Russia, Poland, Scandinavia and Slovakia this pitch is designated B, with 'H' used to designate the B-natural. Since the 1990s, B-flat is often denoted Bb or "Bess" instead of B in Swedish music textbooks. Natural B is called "B" by Swedish jazz and pop musicians, but still denoted H in classical music. See B (musical note) and Note names and their history for explanations.

Common scales beginning on B♭

 * B-flat major: B♭ C D E♭ F G A B♭
 * B-flat natural minor: B♭ C D♭ E♭ F G♭ A♭ B♭
 * B-flat harmonic minor: B♭ C D♭ E♭ F G♭ A B♭
 * B-flat melodic minor ascending: B♭ C D♭ E♭ F G A B♭
 * B-flat melodic minor descending: B♭ A♭ G♭ F E♭ D♭ C B♭

Diatonic scales

 * B-flat Ionian: B♭ C D E♭ F G A B♭
 * B-flat Dorian: B♭ C D♭ E♭ F G A♭ B♭
 * B-flat Phrygian: B♭ C♭ D♭ E♭ F G♭ A♭ B♭
 * B-flat Lydian: B♭ C D E F G A B♭
 * B-flat Mixolydian: B♭ C D E♭ F G A♭ B♭
 * B-flat Aeolian: B♭ C D♭ E♭ F G♭ A♭ B♭
 * B-flat Locrian: B♭ C♭ D♭ E♭ F♭ G♭ A♭ B♭

Jazz melodic minor

 * B-flat ascending melodic minor: B♭ C D♭ E♭ F G A B♭
 * B-flat Dorian ♭2: B♭ C♭ D♭ E♭ F G A♭ B♭
 * B-flat Lydian augmented: B♭ C D E F♯ G A B♭
 * B-flat Lydian dominant: B♭ C D E F G A♭ B♭
 * B-flat Mixolydian ♭6: B♭ C D E♭ F G♭ A♭ B♭
 * B-flat Locrian ♮2: B♭ C D♭ E♭ F♭ G♭ A♭ B♭
 * B-flat altered: B♭ C♭ D♭ E𝄫 F♭ G♭ A♭ B♭