The B♭ Note

B♭ is a black key, immediately next to B. It sounds at 466.16 Hz in octave 4.

B♭ on the piano

Press play to hear the note.

Key facts

On the keyboard
a black key, immediately next to B.
Frequency (octave 4)
466.16 Hz
MIDI number (octave 4)
70
Also written as
A♯
In key signatures
The 1 flat in the order of flats.

B♭ and its enharmonic spellings

B♭ can also be written as A♯. These are enharmonic equivalents: the same pitch, the same key on the piano, a different name on the page. Which spelling is correct depends on the key and on how the note functions, not on the sound.

B♭ frequency in every octave

Frequencies for B♭ in scientific pitch notation, with A4 tuned to 440 Hz.

NoteMIDIFrequency
B♭13458.27 Hz
B♭246116.54 Hz
B♭358233.08 Hz
B♭470466.16 Hz
B♭582932.33 Hz
B♭6941864.66 Hz
B♭71063729.31 Hz

Chords on B♭

The most common chords built with B♭ as the root.

See every B♭ chord

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Scales starting on B♭

Keys and scales that use B♭ as their tonic.

All notes

常见问题

Where is B♭ on the piano?

B♭ is a black key, immediately next to B.

What frequency is B♭4?

B♭4 sounds at 466.16 Hz with A4 tuned to 440 Hz.

What is another name for B♭?

B♭ can also be written as A♯. They are the same pitch spelled differently.