C3
Reviewed for accuracy · Maintained by Justin Evans
C3 highlighted — use the view toggle to see all 88 keys.
Piano key
28 of 88
Octave
3
Frequency
130.81 Hz
MIDI number
48
Key color
White key
Pitch class
C · B# · Dbb
What is C3?
C3 is the C in octave 3 — the 28th key of the 88 on a full-size piano, counted from the bottom. In standard tuning it sounds at 130.81 Hz. It sits 12 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 C.
Every octave doubles the frequency: the C one octave up sounds at 261.62 Hz and the one below at 65.41 Hz. The same piano key can be written as C, B#, Dbb depending on the musical context — same sound, different spelling.
Nearby notes
Every C on the keyboard: