C♯1 at every common reference pitch
A note’s frequency depends on what A4 is tuned to. The standard is 440 Hz; the other three are the ones you are most likely to meet. The cents column is how far each one sits from the 440 version — the same for every note, because changing the reference moves the whole scale together.
| Reference | C♯1 | vs 440 |
|---|---|---|
| A4 = 415 Hz · Baroque pitch | 32.68 Hz | −101.3¢ |
| A4 = 432 Hz · “Verdi” pitch | 34.02 Hz | −31.8¢ |
| A4 = 440 Hz · Standard (ISO 16) | 34.65 Hz | — |
| A4 = 442 Hz · Orchestral | 34.81 Hz | +7.9¢ |
One cycle of C♯1 lasts 28.862 ms, and its wavelength in air at 20 °C is 9.90 m. Hold it as a steady tone in the tone generator.
C♯1 on the piano
C♯1 is key 5 of 88, counting from the bottom — the black key between C and D. Press any key below to compare it with its neighbours.
C♯1 on the guitar
C♯1 is below the guitar’s lowest note, the open low E (E2), so a guitar in standard tuning cannot play it.
C♯1 on the staff
Instruments that can play C♯1
2 instruments play C♯1 within the normal range, and 4 reach it only at the extreme of theirs. Each links to its range chart; for a transposing instrument, the note on its part is shown.
Woodwind
Keyboards and free reeds
Only at the extreme of their range
C♯1 is outside the typical range of all six voice types. Test your own range.
The harmonics of C♯1
A played C♯1 is not one frequency. A string or a pipe also sounds whole-number multiples of it, and the mix of those harmonics is the instrument’s tone. Here is where the first eight land — and why the 7th sounds out of tune against a piano.
| Harmonic | Frequency | Nearest note | Off by |
|---|---|---|---|
| 1 (fundamental) | 34.65 Hz | C♯1 | 0¢ |
| 2 | 69.30 Hz | C♯2 | 0¢ |
| 3 | 103.94 Hz | A♭2 | +2.0¢ |
| 4 | 138.59 Hz | C♯3 | 0¢ |
| 5 | 173.24 Hz | F3 | −13.7¢ |
| 6 | 207.89 Hz | A♭3 | +2.0¢ |
| 7 | 242.53 Hz | B3 | −31.2¢ |
| 8 | 277.18 Hz | C♯4 | 0¢ |
Frequently asked questions
What is the frequency of C♯1?
C♯1 is 34.65 Hz in equal temperament with A4 tuned to 440 Hz, the international standard. At A4 = 432 Hz it is 34.02 Hz, and at the orchestral A4 = 442 Hz it is 34.81 Hz.
Is C♯1 the same note as D♭1?
On a piano, a guitar or a tuner, yes: C♯1 and D♭1 are the same key and the same frequency, 34.65 Hz, in equal temperament. They are two names for one pitch (enharmonic equivalents). Which one is written depends on the key — sharps in sharp keys, flats in flat keys — and a string or wind player may pitch them a few cents apart when playing in just intonation.
How do I play C♯1 on a piano?
C♯1 is key 5 of 88, counting from the bottom — the black key between C and D.
Which instruments can play C♯1?
2 of the instruments we chart play C♯1 within their normal range, including contrabassoon, piano, and 4 more reach it only at the extreme of their range.
Typing it? C♯1 is also written C#1 or Db1. Convert any frequency on the Hz-to-note converter.