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About A♯3
A♯3 / B♭3 has a frequency of 233.08 Hz in standard tuning, where A4 is fixed at 440 Hz. It is MIDI note 58 and key number 38 on an 88-key piano.
In equal temperament every semitone multiplies the frequency by the twelfth root of two (≈1.05946), so A♯3 is 11 semitones below A4: f = 440 × 2^((58 − 69) / 12) = 233.08 Hz. The number in the name is the octave in scientific pitch notation, which starts each octave on C.
A♯3 and B♭3 are enharmonic: on a piano or in equal temperament they are the same key and the same frequency, but they are spelled differently depending on the key signature.
A♯3 frequency in different tunings
| Tuning reference | A♯3 frequency |
|---|---|
| A4 = 440 Hz (ISO 16 standard) | 233.08 Hz |
| A4 = 442 Hz (many European orchestras) | 234.14 Hz |
| A4 = 443 Hz (Berlin, Vienna) | 234.67 Hz |
| A4 = 435 Hz (French diapason normal, 1859) | 230.43 Hz |
| A4 = 432 Hz (alternative tuning) | 228.84 Hz |
| A4 = 415 Hz (Baroque pitch) | 219.84 Hz |
| C4 = 256 Hz (scientific pitch) | 228.07 Hz |
Where to play A♯3 on a guitar
Standard tuning (E A D G B E), frets 0–22.
- 6th string (low E), fret 18
- 5th string (A), fret 13
- 4th string (D), fret 8
- 3rd string (G), fret 3
Intervals from A♯3
| Interval | Note | Frequency | Ratio (just) |
|---|---|---|---|
| Minor second | B3 | 246.94 Hz | 16:15 |
| Major second | C4 | 261.63 Hz | 9:8 |
| Minor third | C♯4 | 277.18 Hz | 6:5 |
| Major third | D4 | 293.66 Hz | 5:4 |
| Perfect fourth | D♯4 | 311.13 Hz | 4:3 |
| Tritone | E4 | 329.63 Hz | 45:32 |
| Perfect fifth | F4 | 349.23 Hz | 3:2 |
| Minor sixth | F♯4 | 369.99 Hz | 8:5 |
| Major sixth | G4 | 392 Hz | 5:3 |
| Minor seventh | G♯4 | 415.3 Hz | 9:5 |
| Major seventh | A4 | 440 Hz | 15:8 |
| Octave | A♯4 | 466.16 Hz | 2:1 |
Instruments and voices that can play A♯3
- Piano (88 keys)
- Guitar (standard tuning)
- Bass guitar (4-string)
- Violin
- Viola
- Cello
- Double bass
- Harp
- 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
Frequently asked questions
What is the frequency of A♯3?
A♯3 is 233.08 Hz when A4 = 440 Hz (228.84 Hz if A4 = 432 Hz).
What MIDI number is A♯3?
A♯3 is MIDI note number 58.
Is A♯3 on a piano?
Yes – it is key 38 of 88.
Where is A♯3 on the guitar?
In standard tuning: 6th string (low E), fret 18; 5th string (A), fret 13; 4th string (D), fret 8; 3rd string (G), fret 3.