A♯4 / B♭4
466.164Hz at concert pitch
Press to hear a pure sine tone at this pitch.
MIDI note
70
Piano key
50
Octave
4
Frequency
466.164 Hz
Period
2.1452 ms
Wavelength
0.7358 m
Pitch class
A♯
Notation
SPN
MIDI is the note number synths and software pass around (0–127). Pitch class is the note without its octave — all the A♯s share one. Enharmonic spellings (A♯4 and B♭4) name the same pitch two ways.
At other reference pitches
| Reference (A4) | A♯4 frequency | Where you meet it |
|---|---|---|
| 432 Hz | 457.688 Hz | the alternative-tuning circle |
| 440 Hzstandard | 466.164 Hz | the ISO 16 standard — concert pitch |
| 442 Hz | 468.283 Hz | many European orchestras tune a touch sharp |
| 443 Hz | 469.342 Hz | some sharper continental orchestras |
Every row is A♯4 — only the A4 you tune to changes. A frequency scales straight with the reference: A♯4 at 432 Hz is the 440 Hz value times 432⁄440.
Move around
Every A♯
Chords with A♯ in them
A♯ appears in each of these — see the whole chord grid.