C♯4 / D♭4
277.183Hz at concert pitch
Press to hear a pure sine tone at this pitch.
MIDI note
61
Piano key
41
Octave
4
Frequency
277.183 Hz
Period
3.6077 ms
Wavelength
1.2374 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♯4 and D♭4) name the same pitch two ways.
At other reference pitches
| Reference (A4) | C♯4 frequency | Where you meet it |
|---|---|---|
| 432 Hz | 272.143 Hz | the alternative-tuning circle |
| 440 Hzstandard | 277.183 Hz | the ISO 16 standard — concert pitch |
| 442 Hz | 278.443 Hz | many European orchestras tune a touch sharp |
| 443 Hz | 279.073 Hz | some sharper continental orchestras |
Every row is C♯4 — only the A4 you tune to changes. A frequency scales straight with the reference: C♯4 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.