B♭4 at every common reference pitch
A note’s frequency depends on what A4 is tuned to. The standard is 440 Hz; the other three are the ones you are most likely to meet. The cents column is how far each one sits from the 440 version — the same for every note, because changing the reference moves the whole scale together.
| Reference | B♭4 | vs 440 |
|---|---|---|
| A4 = 415 Hz · Baroque pitch | 439.68 Hz | −101.3¢ |
| A4 = 432 Hz · “Verdi” pitch | 457.69 Hz | −31.8¢ |
| A4 = 440 Hz · Standard (ISO 16) | 466.16 Hz | — |
| A4 = 442 Hz · Orchestral | 468.28 Hz | +7.9¢ |
One cycle of B♭4 lasts 2.145 ms, and its wavelength in air at 20 °C is 73.6 cm. Hold it as a steady tone in the tone generator.
B♭4 on the piano
B♭4 is key 50 of 88, counting from the bottom — the black key between A and B. Press any key below to compare it with its neighbours.
B♭4 on the guitar
In standard tuning B♭4 is played in 3 places: 3rd (G) string, fret 15, 2nd (B) string, fret 11 and 1st (high E) string, fret 6. The same pitch in each place, with a different tone: lower strings sound warmer. Guitar music is written an octave higher than it sounds, so on a guitar part this note is printed as B♭5.
B♭4 on the staff
Instruments that can play B♭4
44 instruments play B♭4 within the normal range, and 3 reach it only at the extreme of theirs. Each links to its range chart; for a transposing instrument, the note on its part is shown.
Guitars and basses
Plucked and struck strings
Woodwind
Tuned percussion
Only at the extreme of their range
Voices: B♭4 is inside the typical range of the tenor, alto, mezzo-soprano and soprano. Test your own range.
The harmonics of B♭4
A played B♭4 is not one frequency. A string or a pipe also sounds whole-number multiples of it, and the mix of those harmonics is the instrument’s tone. Here is where the first eight land — and why the 7th sounds out of tune against a piano.
| Harmonic | Frequency | Nearest note | Off by |
|---|---|---|---|
| 1 (fundamental) | 466.16 Hz | B♭4 | 0¢ |
| 2 | 932.33 Hz | B♭5 | 0¢ |
| 3 | 1398.5 Hz | F6 | +2.0¢ |
| 4 | 1864.7 Hz | B♭6 | 0¢ |
| 5 | 2330.8 Hz | D7 | −13.7¢ |
| 6 | 2797.0 Hz | F7 | +2.0¢ |
| 7 | 3263.1 Hz | A♭7 | −31.2¢ |
| 8 | 3729.3 Hz | B♭7 | 0¢ |
Frequently asked questions
What is the frequency of B♭4?
B♭4 is 466.16 Hz in equal temperament with A4 tuned to 440 Hz, the international standard. At A4 = 432 Hz it is 457.69 Hz, and at the orchestral A4 = 442 Hz it is 468.28 Hz.
Is B♭4 the same note as A♯4?
On a piano, a guitar or a tuner, yes: B♭4 and A♯4 are the same key and the same frequency, 466.16 Hz, in equal temperament. They are two names for one pitch (enharmonic equivalents). Which one is written depends on the key — sharps in sharp keys, flats in flat keys — and a string or wind player may pitch them a few cents apart when playing in just intonation.
How do I play B♭4 on a piano?
B♭4 is key 50 of 88, counting from the bottom — the black key between A and B.
Which instruments can play B♭4?
44 of the instruments we chart play B♭4 within their normal range, including violin, viola, cello, erhu, guitar, and 3 more reach it only at the extreme of their range.
Typing it? B♭4 is also written Bb4 or A#4. Convert any frequency on the Hz-to-note converter.