C♯2 / D♭2
Reviewed for accuracy · Maintained by Justin Evans
C♯2 highlighted — use the view toggle to see all 88 keys.
Piano key
17 of 88
Octave
2
Frequency
69.3 Hz
MIDI number
37
Key color
Black key
Pitch class
C# · Db · B##
What is C♯2?
C♯2 is the C♯ in octave 2 — the 17th key of the 88 on a full-size piano, counted from the bottom. In standard tuning it sounds at 69.3 Hz. It sits 23 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 C♯.
Every octave doubles the frequency: the C♯ one octave up sounds at 138.6 Hz and the one below at 34.65 Hz. The same piano key can be written as C#, Db, B## depending on the musical context — same sound, different spelling.
Nearby notes
Every C♯ on the keyboard: