B4 at a glance
All values assume twelve-tone equal temperament at the international standard pitch of A4 = 440 Hz. In that system every semitone has the same size - a frequency ratio of 2^(1/12) - so B4 is exactly 440 × 2^(2/12) Hz. Under alternative references the note shifts with the reference: at A4 = 432 Hz, B4 becomes 484.90 Hz.
B in every octave
| Note | Frequency | MIDI | Piano key |
|---|---|---|---|
| B0 | 30.87 Hz | 23 | 3 |
| B1 | 61.74 Hz | 35 | 15 |
| B2 | 123.47 Hz | 47 | 27 |
| B3 | 246.94 Hz | 59 | 39 |
| B4 ← | 493.88 Hz | 71 | 51 |
| B5 | 987.77 Hz | 83 | 63 |
| B6 | 1975.5 Hz | 95 | 75 |
| B7 | 3951.1 Hz | 107 | 87 |
Each octave doubles the frequency - the simplest relationship in music, and the reason notes an octave apart sound like “the same note, higher”.
Neighboring notes
One semitone down is A♯4 at 466.16 Hz; one semitone up is C5 at 523.25 Hz. Need a frequency between notes, or a different waveform? The tone generator plays anything from 20 Hz to 20 kHz; the note ↔ frequency converter does the math both directions, and the chromatic tuner listens to your instrument and shows the offset in cents.