A♯0 — 29.135 Hz
A♯0 (A-sharp 0) is 29.135 Hz in standard equal temperament at A=440 Hz. It is MIDI note number 22. This is the sharp spelling of this pitch — see also B♭0.
A♯ is the leading tone in B major and appears as a key-signature accidental only in sharp keys with 5 or more sharps.
A♯0 Frequency in All Tuning Systems
| Temperament | Frequency (Hz) | Cents from Equal | Common Usage |
|---|---|---|---|
| Equal Temperament | 29.135 Hz | 0.00 | Modern standard; piano, fretted instruments |
| Pythagorean Tuning | 28.971 Hz | -9.77 | Medieval/early music; string ensemble open fifths |
| Just / Pure | 29.433 Hz | +17.62 | A cappella vocal, barbershop, Renaissance |
| Meantone 1/3 Comma | 29.516 Hz | +22.49 | Renaissance vocal music in minor keys |
| Meantone 1/4 Comma | 29.425 Hz | +17.15 | Renaissance keyboard, early Baroque organ |
| 1/6 SC - Attenuated | 29.333 Hz | +11.73 | Baroque orchestral ensemble compromise |
| Kellner's Bach | 29.294 Hz | +9.42 | Bach keyboard reconstruction |
| Kirnberger III | 29.308 Hz | +10.25 | Classical-era keyboard, keys near C major |
| Vallotti | 29.234 Hz | +5.87 | Baroque/Classical orchestral tuning |
| Werckmeister III | 29.333 Hz | +11.73 | Baroque keyboard; Bach contemporaries |
| Werckmeister IV | 29.300 Hz | +9.78 | Baroque keyboard, strong key contrast |
| Werckmeister V | 29.201 Hz | +3.92 | Specialized Baroque keyboard |
Positive cents = sharper than equal temperament. Negative cents = flatter. 100 cents = 1 semitone.
A♯0 at Different Concert Pitches
The same note varies in frequency depending on the concert pitch standard used by your ensemble.
| Concert Pitch | Frequency (Hz) | Common Usage |
|---|---|---|
| A = 440 Hz (ISO standard) | 29.135 Hz | US, UK, and most modern ensembles worldwide |
| A = 442 Hz | 29.268 Hz | Many European orchestras; France, Germany |
| A = 443 Hz | 29.334 Hz | Berlin Philharmonic; some US orchestras |
| A = 432 Hz | 28.606 Hz | Alternative tuning; Baroque revival |
| A = 415 Hz (Baroque) | 27.480 Hz | Historically-informed Baroque performance |
f = f_at_A440 × (concert_pitch / 440)
Instruments That Play A♯0
A♯0 (29.135 Hz) falls within the comfortable playing range of 1 instrument.
A♯0 and B♭0 — Enharmonic Equivalents
A♯0 and B♭0 are enharmonic equivalents — they sound identical at 29.135 Hz but are written differently depending on the musical context.
When to Write A♯0
A♯ is the leading tone in B major and appears as a key-signature accidental only in sharp keys with 5 or more sharps.
Composers write A♯ only when the harmonic context demands sharp-side spelling — most often as the leading tone in B major or in chromatic passages within sharp keys. Because B♭ is far more common, seeing A♯ signals a very specific tonal context: the note is pulling upward toward B in a sharp key.
Major scales containing A♯0: B major (7th / leading tone), F♯ major (3rd), C♯ major (6th).
Minor scales containing A♯0: D♯ minor (5th), A♯ minor (tonic), G♯ minor (2nd).
A♯0 in Instrument Literature
String players encounter A♯ primarily in B major and F♯ major. Pianists see it in heavily sharped key signatures. A♯ is relatively rare in wind and brass literature, where the same pitch is almost always written as B♭.
In fixed-do solfège, A♯ is sung as "li" (♯6). In B major with moveable do, it is "ti" (the leading tone).
How B♭0 Differs in Context
While B♭0 sounds identical to A♯0, it belongs to a different set of keys and carries different harmonic implications.
B♭0: B♭ is the tonic of B♭ major (2 flats) and is the single most common accidental in Western music, appearing as the first flat in any flat key signature.
Major scales: F major (4th), B♭ major (tonic), E♭ major (5th), A♭ major (2nd).
Minor scales: G minor (3rd), D minor (6th), C minor (7th).
B♭ is the transposition interval for B♭ clarinet, B♭ trumpet, and tenor saxophone — they read C but sound B♭. It is arguably the single most important note for concert band and wind ensemble repertoire. Trombonists and tuba players read B♭ constantly in their native flat keys.
Enharmonic equivalents share the same frequency in equal temperament. In historical temperaments like Pythagorean or meantone, they may differ slightly — see the temperament comparison table above for this note's exact deviations.
Why A♯0 Varies Across Tuning Systems
A♯0 shows a maximum deviation of +22.49 cents in Meantone 1/3 Comma compared to equal temperament. This 22-cent difference is clearly audible to trained musicians and reflects how different tuning philosophies prioritize interval purity over equal distribution.
In Meantone 1/3 Comma, A♯0 is tuned sharper than equal temperament to achieve purer intervals with nearby notes in the tuning system's favored keys.
6 of the 15 non-equal temperaments deviate by more than 10 cents for A♯0, making this note one where tuning system choice has a meaningful impact on pitch.
A♯0 Across All Tuning Systems
Explore how A♯0 is tuned in each historical temperament system. Each tuning system gives A♯0 a slightly different frequency, affecting the harmonic character of chords and melodies.
A♯0 in Historical Temperament Systems
Explore how A♯0 (29.135 Hz in equal temperament) is tuned in each of the 15 historical non-equal temperament systems. Each system places A♯0 at a slightly different frequency based on its mathematical basis.
Tune A♯0 with precision — Get Tunable.
Tunable supports 15+ tuning systems including equal temperament, Pythagorean, just intonation, and historical well-temperaments. See exact Hz values in real-time as you play.
