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About B4
B4 has a frequency of 493.88 Hz in standard tuning, where A4 is fixed at 440 Hz. It is MIDI note 71 and key number 51 on an 88-key piano.
In equal temperament every semitone multiplies the frequency by the twelfth root of two (≈1.05946), so B4 is 2 semitones above A4: f = 440 × 2^((71 − 69) / 12) = 493.88 Hz. The number in the name is the octave in scientific pitch notation, which starts each octave on C.
B4 frequency in different tunings
| Tuning reference | B4 frequency |
|---|---|
| A4 = 440 Hz (ISO 16 standard) | 493.88 Hz |
| A4 = 442 Hz (many European orchestras) | 496.13 Hz |
| A4 = 443 Hz (Berlin, Vienna) | 497.25 Hz |
| A4 = 435 Hz (French diapason normal, 1859) | 488.27 Hz |
| A4 = 432 Hz (alternative tuning) | 484.9 Hz |
| A4 = 415 Hz (Baroque pitch) | 465.82 Hz |
| C4 = 256 Hz (scientific pitch) | 483.26 Hz |
Where to play B4 on a guitar
Standard tuning (E A D G B E), frets 0–22.
- 4th string (D), fret 21
- 3rd string (G), fret 16
- 2nd string (B), fret 12
- 1st string (high E), fret 7
Intervals from B4
| Interval | Note | Frequency | Ratio (just) |
|---|---|---|---|
| Minor second | C5 | 523.25 Hz | 16:15 |
| Major second | C♯5 | 554.37 Hz | 9:8 |
| Minor third | D5 | 587.33 Hz | 6:5 |
| Major third | D♯5 | 622.25 Hz | 5:4 |
| Perfect fourth | E5 | 659.26 Hz | 4:3 |
| Tritone | F5 | 698.46 Hz | 45:32 |
| Perfect fifth | F♯5 | 739.99 Hz | 3:2 |
| Minor sixth | G5 | 783.99 Hz | 8:5 |
| Major sixth | G♯5 | 830.61 Hz | 5:3 |
| Minor seventh | A5 | 880 Hz | 9:5 |
| Major seventh | A♯5 | 932.33 Hz | 15:8 |
| Octave | B5 | 987.77 Hz | 2:1 |
Instruments and voices that can play B4
- Piano (88 keys)
- Guitar (standard tuning)
- Violin
- Viola
- Cello
- Harp
- Flute
- Clarinet (B♭, sounding)
- Oboe
- Bassoon
- Alto saxophone (sounding)
- Tenor saxophone (sounding)
- Trumpet (B♭, sounding)
- French horn (sounding)
- Trombone
- Tenor voice
- Alto voice
- Mezzo-soprano voice
- Soprano voice
Frequently asked questions
What is the frequency of B4?
B4 is 493.88 Hz when A4 = 440 Hz (484.9 Hz if A4 = 432 Hz).
What MIDI number is B4?
B4 is MIDI note number 71.
Is B4 on a piano?
Yes – it is key 51 of 88.
Where is B4 on the guitar?
In standard tuning: 4th string (D), fret 21; 3rd string (G), fret 16; 2nd string (B), fret 12; 1st string (high E), fret 7.