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About C♯5
C♯5 / D♭5 has a frequency of 554.37 Hz in standard tuning, where A4 is fixed at 440 Hz. It is MIDI note 73 and key number 53 on an 88-key piano.
In equal temperament every semitone multiplies the frequency by the twelfth root of two (≈1.05946), so C♯5 is 4 semitones above A4: f = 440 × 2^((73 − 69) / 12) = 554.37 Hz. The number in the name is the octave in scientific pitch notation, which starts each octave on C.
C♯5 and D♭5 are enharmonic: on a piano or in equal temperament they are the same key and the same frequency, but they are spelled differently depending on the key signature.
C♯5 frequency in different tunings
| Tuning reference | C♯5 frequency |
|---|---|
| A4 = 440 Hz (ISO 16 standard) | 554.37 Hz |
| A4 = 442 Hz (many European orchestras) | 556.89 Hz |
| A4 = 443 Hz (Berlin, Vienna) | 558.15 Hz |
| A4 = 435 Hz (French diapason normal, 1859) | 548.07 Hz |
| A4 = 432 Hz (alternative tuning) | 544.29 Hz |
| A4 = 415 Hz (Baroque pitch) | 522.87 Hz |
| C4 = 256 Hz (scientific pitch) | 542.45 Hz |
Where to play C♯5 on a guitar
Standard tuning (E A D G B E), frets 0–22.
- 3rd string (G), fret 18
- 2nd string (B), fret 14
- 1st string (high E), fret 9
Intervals from C♯5
| Interval | Note | Frequency | Ratio (just) |
|---|---|---|---|
| Minor second | D5 | 587.33 Hz | 16:15 |
| Major second | D♯5 | 622.25 Hz | 9:8 |
| Minor third | E5 | 659.26 Hz | 6:5 |
| Major third | F5 | 698.46 Hz | 5:4 |
| Perfect fourth | F♯5 | 739.99 Hz | 4:3 |
| Tritone | G5 | 783.99 Hz | 45:32 |
| Perfect fifth | G♯5 | 830.61 Hz | 3:2 |
| Minor sixth | A5 | 880 Hz | 8:5 |
| Major sixth | A♯5 | 932.33 Hz | 5:3 |
| Minor seventh | B5 | 987.77 Hz | 9:5 |
| Major seventh | C6 | 1.047 kHz | 15:8 |
| Octave | C♯6 | 1.109 kHz | 2:1 |
Instruments and voices that can play C♯5
Frequently asked questions
What is the frequency of C♯5?
C♯5 is 554.37 Hz when A4 = 440 Hz (544.29 Hz if A4 = 432 Hz).
What MIDI number is C♯5?
C♯5 is MIDI note number 73.
Is C♯5 on a piano?
Yes – it is key 53 of 88.
Where is C♯5 on the guitar?
In standard tuning: 3rd string (G), fret 18; 2nd string (B), fret 14; 1st string (high E), fret 9.