A♯2 / B♭2
Reviewed for accuracy · Maintained by Justin Evans
A♯2 highlighted — use the view toggle to see all 88 keys.
Piano key
26 of 88
Octave
2
Frequency
116.54 Hz
MIDI number
46
Key color
Black key
Pitch class
A# · Bb · Cbb
What is A♯2?
A♯2 is the A♯ in octave 2 — the 26th key of the 88 on a full-size piano, counted from the bottom. In standard tuning it sounds at 116.54 Hz. It sits 14 half-steps below middle C (C4).
To find it, locate any group of two black keys: the white key just to their left is a C. Count down from middle C (C4) 2 octaves to reach octave 2, then step to A♯.
Every octave doubles the frequency: the A♯ one octave up sounds at 233.08 Hz and the one below at 58.27 Hz. The same piano key can be written as A#, Bb, Cbb depending on the musical context — same sound, different spelling.
Nearby notes
Every A♯ on the keyboard: