61.74Hz
Start with your device volume low. Very low tones may be inaudible on phone or laptop speakers; very high tones can be uncomfortable on headphones.
61.74 HzFrequency at A4 = 440 Hz
35MIDI note number
15Piano key (of 88)
5.56 mWavelength in air
About B1
B1 has a frequency of 61.74 Hz in standard tuning, where A4 is fixed at 440 Hz. It is MIDI note 35 and key number 15 on an 88-key piano.
In equal temperament every semitone multiplies the frequency by the twelfth root of two (≈1.05946), so B1 is 34 semitones below A4: f = 440 × 2^((35 − 69) / 12) = 61.74 Hz. The number in the name is the octave in scientific pitch notation, which starts each octave on C.
B1 frequency in different tunings
| Tuning reference | B1 frequency |
|---|---|
| A4 = 440 Hz (ISO 16 standard) | 61.74 Hz |
| A4 = 442 Hz (many European orchestras) | 62.02 Hz |
| A4 = 443 Hz (Berlin, Vienna) | 62.16 Hz |
| A4 = 435 Hz (French diapason normal, 1859) | 61.03 Hz |
| A4 = 432 Hz (alternative tuning) | 60.61 Hz |
| A4 = 415 Hz (Baroque pitch) | 58.23 Hz |
| C4 = 256 Hz (scientific pitch) | 60.41 Hz |
Intervals from B1
| Interval | Note | Frequency | Ratio (just) |
|---|---|---|---|
| Minor second | C2 | 65.41 Hz | 16:15 |
| Major second | C♯2 | 69.3 Hz | 9:8 |
| Minor third | D2 | 73.42 Hz | 6:5 |
| Major third | D♯2 | 77.78 Hz | 5:4 |
| Perfect fourth | E2 | 82.41 Hz | 4:3 |
| Tritone | F2 | 87.31 Hz | 45:32 |
| Perfect fifth | F♯2 | 92.5 Hz | 3:2 |
| Minor sixth | G2 | 98 Hz | 8:5 |
| Major sixth | G♯2 | 103.83 Hz | 5:3 |
| Minor seventh | A2 | 110 Hz | 9:5 |
| Major seventh | A♯2 | 116.54 Hz | 15:8 |
| Octave | B2 | 123.47 Hz | 2:1 |
Instruments and voices that can play B1
Frequently asked questions
What is the frequency of B1?
B1 is 61.74 Hz when A4 = 440 Hz (60.61 Hz if A4 = 432 Hz).
What MIDI number is B1?
B1 is MIDI note number 35.
Is B1 on a piano?
Yes – it is key 15 of 88.