The A♯ Note

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

A♯ on the piano

Press play to hear the note.

Key facts

On the keyboard
a black key, immediately next to A.
Frequency (octave 4)
466.16 Hz
MIDI number (octave 4)
70
Also written as
B♭
In key signatures
The 5 sharp in the order of sharps.

A♯ and its enharmonic spellings

A♯ can also be written as B♭. 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.

A♯ frequency in every octave

Frequencies for A♯ in scientific pitch notation, with A4 tuned to 440 Hz.

NoteMIDIFrequency
A♯13458.27 Hz
A♯246116.54 Hz
A♯358233.08 Hz
A♯470466.16 Hz
A♯582932.33 Hz
A♯6941864.66 Hz
A♯71063729.31 Hz

Chords on A♯

The most common chords built with A♯ as the root.

See every A♯ chord

Piano Companion
Piano Companion
Chords, Scales & Progressions

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Scales starting on A♯

Keys and scales that use A♯ as their tonic.

All notes

अक्सर पूछे जाने वाले प्रश्न

Where is A♯ on the piano?

A♯ is a black key, immediately next to A.

What frequency is A♯4?

A♯4 sounds at 466.16 Hz with A4 tuned to 440 Hz.

What is another name for A♯?

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