C5
523.251Hz at concert pitch
Press to hear a pure sine tone at this pitch.
MIDI note
72
Piano key
52
Octave
5
Frequency
523.251 Hz
Period
1.9111 ms
Wavelength
0.6555 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 72 is C5. Yamaha gear labels the same key C4 and some trackers call it C6. The MIDI number never moves — only the octave name printed on the box does.
At other reference pitches
| Reference (A4) | C5 frequency | Where you meet it |
|---|---|---|
| 432 Hz | 513.737 Hz | the alternative-tuning circle |
| 440 Hzstandard | 523.251 Hz | the ISO 16 standard — concert pitch |
| 442 Hz | 525.63 Hz | many European orchestras tune a touch sharp |
| 443 Hz | 526.819 Hz | some sharper continental orchestras |
Every row is C5 — only the A4 you tune to changes. A frequency scales straight with the reference: C5 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.