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About C4
C4 (middle C) has a frequency of 261.63 Hz in standard tuning, where A4 is fixed at 440 Hz. It is MIDI note 60 and key number 40 on an 88-key piano.
C4 is middle C – the C nearest the middle of the piano keyboard and the dividing line between the treble and bass clefs.
In equal temperament every semitone multiplies the frequency by the twelfth root of two (≈1.05946), so C4 is 9 semitones below A4: f = 440 × 2^((60 − 69) / 12) = 261.63 Hz. The number in the name is the octave in scientific pitch notation, which starts each octave on C.
C4 frequency in different tunings
| Tuning reference | C4 frequency |
|---|---|
| A4 = 440 Hz (ISO 16 standard) | 261.63 Hz |
| A4 = 442 Hz (many European orchestras) | 262.81 Hz |
| A4 = 443 Hz (Berlin, Vienna) | 263.41 Hz |
| A4 = 435 Hz (French diapason normal, 1859) | 258.65 Hz |
| A4 = 432 Hz (alternative tuning) | 256.87 Hz |
| A4 = 415 Hz (Baroque pitch) | 246.76 Hz |
| C4 = 256 Hz (scientific pitch) | 256 Hz |
Where to play C4 on a guitar
Standard tuning (E A D G B E), frets 0–22.
- 6th string (low E), fret 20
- 5th string (A), fret 15
- 4th string (D), fret 10
- 3rd string (G), fret 5
- 2nd string (B), fret 1
Intervals from C4
| Interval | Note | Frequency | Ratio (just) |
|---|---|---|---|
| Minor second | C♯4 | 277.18 Hz | 16:15 |
| Major second | D4 | 293.66 Hz | 9:8 |
| Minor third | D♯4 | 311.13 Hz | 6:5 |
| Major third | E4 | 329.63 Hz | 5:4 |
| Perfect fourth | F4 | 349.23 Hz | 4:3 |
| Tritone | F♯4 | 369.99 Hz | 45:32 |
| Perfect fifth | G4 | 392 Hz | 3:2 |
| Minor sixth | G♯4 | 415.3 Hz | 8:5 |
| Major sixth | A4 | 440 Hz | 5:3 |
| Minor seventh | A♯4 | 466.16 Hz | 9:5 |
| Major seventh | B4 | 493.88 Hz | 15:8 |
| Octave | C5 | 523.25 Hz | 2:1 |
Instruments and voices that can play C4
- Piano (88 keys)
- Guitar (standard tuning)
- Bass guitar (4-string)
- Violin
- Viola
- Cello
- Double bass
- Harp
- Flute
- Clarinet (B♭, sounding)
- Oboe
- Bassoon
- Alto saxophone (sounding)
- Tenor saxophone (sounding)
- Trumpet (B♭, sounding)
- French horn (sounding)
- Trombone
- Tuba
- Bass voice
- Baritone voice
- Tenor voice
- Alto voice
- Mezzo-soprano voice
- Soprano voice
Frequently asked questions
What is the frequency of C4?
C4 is 261.63 Hz when A4 = 440 Hz (256.87 Hz if A4 = 432 Hz).
What MIDI number is C4?
C4 is MIDI note number 60.
Is C4 on a piano?
Yes – it is key 40 of 88.
Where is C4 on the guitar?
In standard tuning: 6th string (low E), fret 20; 5th string (A), fret 15; 4th string (D), fret 10; 3rd string (G), fret 5.