It lies a diatonic semitone above A and a chromatic semitone below B, thus being enharmonic to A♯ although in some musical tunings, B♭ will have a different sounding pitch than A♯. B-flat is also enharmonic to C.
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 pitch (music) for a discussion of historical variations in frequency.
In Germany, Russia, Poland and Scandinavia this pitch is designated B, with 'H' used to designate the B-natural (or enharmonically C♭). 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) for an explanation.
|Scientific designation||Helmholtz designation||Bilinear music notation||Octave name||Frequency (Hz)|
|B♭−1||B♭͵͵͵ or ͵͵͵B♭ or BBBB♭||(-uB♭)||Subsubcontra||14.568|
|B♭0||B♭͵͵ or ͵͵B♭ or BBB♭||(-vB♭)||Subcontra||29.135|
|B♭1||B♭͵ or ͵B♭ or BB♭||(-wB♭)||Contra||58.270|