C♯0 / D♭0
17.324Hz at concert pitch
Press to hear a pure sine tone at this pitch.
MIDI note
13
Piano key
—
Octave
0
Frequency
17.324 Hz
Period
57.7234 ms
Wavelength
19.7991 m
Pitch class
C♯
Notation
SPN
MIDI is the note number synths and software pass around (0–127). Pitch class is the note without its octave — all the C♯s share one. Enharmonic spellings (C♯0 and D♭0) name the same pitch two ways. This note falls outside the 88-key piano, so it has no piano key number.
At other reference pitches
| Reference (A4) | C♯0 frequency | Where you meet it |
|---|---|---|
| 432 Hz | 17.009 Hz | the alternative-tuning circle |
| 440 Hzstandard | 17.324 Hz | the ISO 16 standard — concert pitch |
| 442 Hz | 17.403 Hz | many European orchestras tune a touch sharp |
| 443 Hz | 17.442 Hz | some sharper continental orchestras |
Every row is C♯0 — only the A4 you tune to changes. A frequency scales straight with the reference: C♯0 at 432 Hz is the 440 Hz value times 432⁄440.
Move around
Every C♯
Chords with C♯ in them
C♯ appears in each of these — see the whole chord grid.