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About C♯7
C♯7 / D♭7 has a frequency of 2.217 kHz in standard tuning, where A4 is fixed at 440 Hz. It is MIDI note 97 and key number 77 on an 88-key piano.
In equal temperament every semitone multiplies the frequency by the twelfth root of two (≈1.05946), so C♯7 is 28 semitones above A4: f = 440 × 2^((97 − 69) / 12) = 2,217.46 Hz. The number in the name is the octave in scientific pitch notation, which starts each octave on C.
C♯7 and D♭7 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♯7 frequency in different tunings
| Tuning reference | C♯7 frequency |
|---|---|
| A4 = 440 Hz (ISO 16 standard) | 2.217 kHz |
| A4 = 442 Hz (many European orchestras) | 2.228 kHz |
| A4 = 443 Hz (Berlin, Vienna) | 2.233 kHz |
| A4 = 435 Hz (French diapason normal, 1859) | 2.192 kHz |
| A4 = 432 Hz (alternative tuning) | 2.177 kHz |
| A4 = 415 Hz (Baroque pitch) | 2.091 kHz |
| C4 = 256 Hz (scientific pitch) | 2.17 kHz |
Intervals from C♯7
| Interval | Note | Frequency | Ratio (just) |
|---|---|---|---|
| Minor second | D7 | 2.349 kHz | 16:15 |
| Major second | D♯7 | 2.489 kHz | 9:8 |
| Minor third | E7 | 2.637 kHz | 6:5 |
| Major third | F7 | 2.794 kHz | 5:4 |
| Perfect fourth | F♯7 | 2.96 kHz | 4:3 |
| Tritone | G7 | 3.136 kHz | 45:32 |
| Perfect fifth | G♯7 | 3.322 kHz | 3:2 |
| Minor sixth | A7 | 3.52 kHz | 8:5 |
| Major sixth | A♯7 | 3.729 kHz | 5:3 |
| Minor seventh | B7 | 3.951 kHz | 9:5 |
| Major seventh | C8 | 4.186 kHz | 15:8 |
| Octave | C♯8 | 4.435 kHz | 2:1 |
Instruments and voices that can play C♯7
Frequently asked questions
What is the frequency of C♯7?
C♯7 is 2.217 kHz when A4 = 440 Hz (2.177 kHz if A4 = 432 Hz).
What MIDI number is C♯7?
C♯7 is MIDI note number 97.
Is C♯7 on a piano?
Yes – it is key 77 of 88.