C♯4 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♯4 | vs 440 |
|---|---|---|
| A4 = 415 Hz · Baroque pitch | 261.43 Hz | −101.3¢ |
| A4 = 432 Hz · “Verdi” pitch | 272.14 Hz | −31.8¢ |
| A4 = 440 Hz · Standard (ISO 16) | 277.18 Hz | — |
| A4 = 442 Hz · Orchestral | 278.44 Hz | +7.9¢ |
One cycle of C♯4 lasts 3.608 ms, and its wavelength in air at 20 °C is 1.24 m. Hold it as a steady tone in the tone generator.
C♯4 on the piano
C♯4 is key 41 of 88, counting from the bottom — the black key between C and D. Press any key below to compare it with its neighbours.
C♯4 on the guitar
In standard tuning C♯4 is played in 4 places: 5th (A) string, fret 16, 4th (D) string, fret 11, 3rd (G) string, fret 6 and 2nd (B) string, fret 2. The same pitch in each place, with a different tone: lower strings sound warmer. Guitar music is written an octave higher than it sounds, so on a guitar part this note is printed as C♯5.
C♯4 on the staff
Instruments that can play C♯4
45 instruments play C♯4 within the normal range, and 2 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.
Guitars and basses
Plucked and struck strings
Woodwind
Brass
Tuned percussion
Only at the extreme of their range
Voices: C♯4 is inside the typical range of the bass, baritone, tenor, alto, mezzo-soprano and soprano. Test your own range.
The harmonics of C♯4
A played C♯4 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) | 277.18 Hz | C♯4 | 0¢ |
| 2 | 554.37 Hz | C♯5 | 0¢ |
| 3 | 831.55 Hz | A♭5 | +2.0¢ |
| 4 | 1108.7 Hz | C♯6 | 0¢ |
| 5 | 1385.9 Hz | F6 | −13.7¢ |
| 6 | 1663.1 Hz | A♭6 | +2.0¢ |
| 7 | 1940.3 Hz | B6 | −31.2¢ |
| 8 | 2217.5 Hz | C♯7 | 0¢ |
Frequently asked questions
What is the frequency of C♯4?
C♯4 is 277.18 Hz in equal temperament with A4 tuned to 440 Hz, the international standard. At A4 = 432 Hz it is 272.14 Hz, and at the orchestral A4 = 442 Hz it is 278.44 Hz.
Is C♯4 the same note as D♭4?
On a piano, a guitar or a tuner, yes: C♯4 and D♭4 are the same key and the same frequency, 277.18 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♯4 on a piano?
C♯4 is key 41 of 88, counting from the bottom — the black key between C and D.
Which instruments can play C♯4?
45 of the instruments we chart play C♯4 within their normal range, including violin, viola, cello, guitar, 7-string guitar, and 2 more reach it only at the extreme of their range.
Typing it? C♯4 is also written C#4 or Db4. Convert any frequency on the Hz-to-note converter.