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About A♯7
A♯7 / B♭7 has a frequency of 3.729 kHz in standard tuning, where A4 is fixed at 440 Hz. It is MIDI note 106 and key number 86 on an 88-key piano.
In equal temperament every semitone multiplies the frequency by the twelfth root of two (≈1.05946), so A♯7 is 37 semitones above A4: f = 440 × 2^((106 − 69) / 12) = 3,729.31 Hz. The number in the name is the octave in scientific pitch notation, which starts each octave on C.
A♯7 and B♭7 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♯7 frequency in different tunings
| Tuning reference | A♯7 frequency |
|---|---|
| A4 = 440 Hz (ISO 16 standard) | 3.729 kHz |
| A4 = 442 Hz (many European orchestras) | 3.746 kHz |
| A4 = 443 Hz (Berlin, Vienna) | 3.755 kHz |
| A4 = 435 Hz (French diapason normal, 1859) | 3.687 kHz |
| A4 = 432 Hz (alternative tuning) | 3.662 kHz |
| A4 = 415 Hz (Baroque pitch) | 3.517 kHz |
| C4 = 256 Hz (scientific pitch) | 3.649 kHz |
Intervals from A♯7
| Interval | Note | Frequency | Ratio (just) |
|---|---|---|---|
| Minor second | B7 | 3.951 kHz | 16:15 |
| Major second | C8 | 4.186 kHz | 9:8 |
| Minor third | C♯8 | 4.435 kHz | 6:5 |
| Major third | D8 | 4.699 kHz | 5:4 |
| Perfect fourth | D♯8 | 4.978 kHz | 4:3 |
| Tritone | E8 | 5.274 kHz | 45:32 |
| Perfect fifth | F8 | 5.588 kHz | 3:2 |
| Minor sixth | F♯8 | 5.92 kHz | 8:5 |
| Major sixth | G8 | 6.272 kHz | 5:3 |
| Minor seventh | G♯8 | 6.645 kHz | 9:5 |
| Major seventh | A8 | 7.04 kHz | 15:8 |
| Octave | A♯8 | 7.459 kHz | 2:1 |
Instruments and voices that can play A♯7
Frequently asked questions
What is the frequency of A♯7?
A♯7 is 3.729 kHz when A4 = 440 Hz (3.662 kHz if A4 = 432 Hz).
What MIDI number is A♯7?
A♯7 is MIDI note number 106.
Is A♯7 on a piano?
Yes – it is key 86 of 88.