A2 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 | A2 | vs 440 |
|---|---|---|
| A4 = 415 Hz · Baroque pitch | 103.75 Hz | −101.3¢ |
| A4 = 432 Hz · “Verdi” pitch | 108.00 Hz | −31.8¢ |
| A4 = 440 Hz · Standard (ISO 16) | 110.00 Hz | — |
| A4 = 442 Hz · Orchestral | 110.50 Hz | +7.9¢ |
One cycle of A2 lasts 9.091 ms, and its wavelength in air at 20 °C is 3.12 m. Hold it as a steady tone in the tone generator.
A2 on the piano
A2 is key 25 of 88, counting from the bottom — a white key. Press any key below to compare it with its neighbours.
A2 on the guitar
In standard tuning A2 is played in 2 places: 6th (low E) string, fret 5 and 5th (A) string open. 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 A3.
A2 on the staff
Instruments that can play A2
25 instruments play A2 within the normal range. Each links to its range chart; for a transposing instrument, the note on its part is shown.
Bowed strings
Guitars and basses
Woodwind
Keyboards and free reeds
Voices: A2 is inside the typical range of the bass and baritone. Test your own range.
The harmonics of A2
A played A2 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) | 110.00 Hz | A2 | 0¢ |
| 2 | 220.00 Hz | A3 | 0¢ |
| 3 | 330.00 Hz | E4 | +2.0¢ |
| 4 | 440.00 Hz | A4 | 0¢ |
| 5 | 550.00 Hz | C♯5 | −13.7¢ |
| 6 | 660.00 Hz | E5 | +2.0¢ |
| 7 | 770.00 Hz | G5 | −31.2¢ |
| 8 | 880.00 Hz | A5 | 0¢ |
Frequencies that land on A2
Frequently asked questions
What is the frequency of A2?
A2 is 110.00 Hz in equal temperament with A4 tuned to 440 Hz, the international standard. At A4 = 432 Hz it is 108.00 Hz, and at the orchestral A4 = 442 Hz it is 110.50 Hz.
Which octave is A2 in?
The number is the octave in scientific pitch notation, where each octave starts on C and C4 is middle C. A2 is in octave 2, 15 semitones below middle C. In Helmholtz notation, used in older books, it is written A.
How do I play A2 on a piano?
A2 is key 25 of 88, counting from the bottom — a white key.
Which instruments can play A2?
25 of the instruments we chart play A2 within their normal range, including cello, double bass, guitar, 7-string guitar, 8-string guitar.
Typing it? A2 is also written A2. Convert any frequency on the Hz-to-note converter.