B♭4 : 466.164 Hz
B♭4 (B-flat 4) is 466.164 Hz in standard equal temperament at A=440 Hz. It is MIDI note number 70. This is the flat spelling of this pitch, see also A♯4.
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.
B♭4 Frequency in All Tuning Systems
| Temperament | Frequency (Hz) | Cents from Equal | Common Usage |
|---|---|---|---|
| Equal Temperament | 466.164 Hz | 0.00 | Modern standard; piano, fretted instruments |
| Pythagorean Tuning | 463.538 Hz | -9.78 | Medieval/early music; string ensemble open fifths |
| Just / Pure | 470.926 Hz | +17.60 | A cappella vocal, barbershop, Renaissance |
| Meantone 1/3 Comma | 472.256 Hz | +22.48 | Renaissance vocal music in minor keys |
| Meantone 1/4 Comma | 470.794 Hz | +17.11 | Renaissance keyboard, early Baroque organ |
| 1/6 SC - Attenuated | 469.333 Hz | +11.73 | Baroque orchestral ensemble compromise |
| Kellner's Bach | 468.696 Hz | +9.38 | Bach keyboard reconstruction |
| Kirnberger III | 468.935 Hz | +10.26 | Classical-era keyboard, keys near C major |
| Vallotti | 467.747 Hz | +5.87 | Baroque/Classical orchestral tuning |
| Werckmeister III | 469.333 Hz | +11.73 | Baroque keyboard; Bach contemporaries |
| Werckmeister IV | 468.805 Hz | +9.78 | Baroque keyboard, strong key contrast |
| Werckmeister V | 467.218 Hz | +3.91 | Specialized Baroque keyboard |
Positive cents = sharper than equal temperament. Negative cents = flatter. 100 cents = 1 semitone.
B♭4 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) | 466.164 Hz | US, UK, and most modern ensembles worldwide |
| A = 442 Hz | 468.283 Hz | Many European orchestras; France, Germany |
| A = 443 Hz | 469.342 Hz | Berlin Philharmonic; some US orchestras |
| A = 432 Hz | 457.688 Hz | Alternative tuning; Baroque revival |
| A = 415 Hz (Baroque) | 439.677 Hz | Historically-informed Baroque performance |
f = f_at_A440 × (concert_pitch / 440)
Instruments That Play B♭4
B♭4 (466.164 Hz) falls within the comfortable playing range of 44 instruments.
B♭4 and A♯4: Enharmonic Equivalents
B♭4 and A♯4 are enharmonic equivalents, they sound identical at 466.164 Hz but are written differently depending on the musical context.
When to Write B♭4
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.
B♭ is overwhelmingly preferred over A♯ in standard notation. As the first flat in the flat-key order (B♭, E♭, A♭, D♭, G♭, C♭, F♭), it appears in F major onward. Jazz, pop, and orchestral music virtually always spell this note as B♭. Even in sharp-side contexts, many publishers prefer B♭ for readability.
Major scales containing B♭4: F major (4th), B♭ major (tonic), E♭ major (5th), A♭ major (2nd).
Minor scales containing B♭4: G minor (3rd), D minor (6th), C minor (7th).
B♭4 in Instrument Literature
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.
In fixed-do solfège, B♭ is sung as "te" (♭7). In B♭ major with moveable do, it is "do" (the tonic). In F major, it is "fa" (the 4th degree).
How A♯4 Differs in Context
While A♯4 sounds identical to B♭4, it belongs to a different set of keys and carries different harmonic implications.
A♯4: A♯ is the leading tone in B major and appears as a key-signature accidental only in sharp keys with 5 or more sharps.
Major scales: B major (7th / leading tone), F♯ major (3rd), C♯ major (6th).
Minor scales: D♯ minor (5th), A♯ minor (tonic), G♯ minor (2nd).
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♭.
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 B♭4 Varies Across Tuning Systems
B♭4 shows a maximum deviation of +22.48 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, B♭4 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 B♭4, making this note one where tuning system choice has a meaningful impact on pitch.
B♭4 Across All Tuning Systems
Explore how B♭4 is tuned in each historical temperament system. Each tuning system gives B♭4 a slightly different frequency, affecting the harmonic character of chords and melodies.
B♭4 in Historical Temperament Systems
Explore how B♭4 (466.164 Hz in equal temperament) is tuned in each of the 15 historical non-equal temperament systems. Each system places B♭4 at a slightly different frequency based on its mathematical basis.
Tune B♭4 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.
