C4
Middle C
C4 highlighted — use the view toggle to see all 88 keys.
Piano key
40 of 88
Octave
4
Frequency
261.63 Hz
MIDI number
60
Key color
White key
Pitch class
C, B#, Dbb
What is C4?
C4 is the C in octave 4 — the 40th key of the 88 on a full-size piano, counted from the bottom. In standard tuning it sounds at 261.63 Hz. It sits at the very center of the keyboard — the reference point pianists navigate from.
To find it, locate any group of two black keys: the white key just to their left is a C. The C nearest the middle of the keyboard is this note.
Every octave doubles the frequency: the C one octave up sounds at 523.26 Hz and the one below at 130.82 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: