C4
261.626Hz at concert pitch
Press to hear a pure sine tone at this pitch.
MIDI note
60
Piano key
40
Octave
4
Frequency
261.626 Hz
Period
3.8223 ms
Wavelength
1.311 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 Cs share one.
The octave-numbering trap: this site uses scientific pitch notation, where MIDI 60 is C4. Yamaha gear labels the same key C3 and some trackers call it C5. The MIDI number never moves — only the octave name printed on the box does.
At other reference pitches
| Reference (A4) | C4 frequency | Where you meet it |
|---|---|---|
| 432 Hz | 256.869 Hz | the alternative-tuning circle |
| 440 Hzstandard | 261.626 Hz | the ISO 16 standard — concert pitch |
| 442 Hz | 262.815 Hz | many European orchestras tune a touch sharp |
| 443 Hz | 263.409 Hz | some sharper continental orchestras |
Every row is C4 — only the A4 you tune to changes. A frequency scales straight with the reference: C4 at 432 Hz is the 440 Hz value times 432⁄440.
About this note
Middle C — the note that sits near the middle of the piano and the centre of the grand staff. In scientific pitch notation this is C4 (MIDI note 60), but the numbering is a famous trap: Yamaha synthesizers label the same key C3, and some music trackers call it C5. The MIDI number never moves — only the octave name people print on the box does. When someone says "C3", ask which convention.
Move around
Every C
Chords with C in them
C appears in each of these — see the whole chord grid.