A3
A3 highlighted — use the view toggle to see all 88 keys.
Piano key
37 of 88
Octave
3
Frequency
220 Hz
MIDI number
57
Key color
White key
Pitch class
A, G##, Bbb
What is A3?
A3 is the A in octave 3 — the 37th key of the 88 on a full-size piano, counted from the bottom. In standard tuning it sounds at 220 Hz. It sits 3 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) 1 octave to reach octave 3, then step to A.
Every octave doubles the frequency: the A one octave up sounds at 440 Hz and the one below at 110 Hz. The same piano key can be written as A, G##, Bbb depending on the musical context — same sound, different spelling.
Nearby notes
Every A on the keyboard: