C#4 — 277.18 Hz
C#4 (MIDI 61) vibrates 277.18 times per second at standard concert pitch. Play the reference tone below, or tune to it with the online tuner.
C#4 at different reference pitches
| Reference (A4) | C#4 frequency | Used for |
|---|---|---|
| 415 Hz | 261.43 Hz | Baroque pitch |
| 432 Hz | 272.14 Hz | “Verdi” pitch |
| 440 Hz | 277.18 Hz | Standard concert pitch |
| 442 Hz | 278.44 Hz | European orchestras |
| 444 Hz | 279.70 Hz | European orchestras |
Physical properties
- Period: one cycle every 3.61 ms
- Wavelength in air: ≈ 1.24 m (at 20 °C, 343 m/s)
- MIDI note number: 61
- Octave up: C#5 = 554.37 Hz · Octave down: 138.59 Hz