A2 on the staff and the piano
On the bass clef, A2 sits in the first space from the bottom.
On the piano, A2 is key 25 of 88, octave 2 - a white key. It is 15 semitones below middle C (C4, key 40).
Play it on the online piano, or see all 88 note frequencies on one page.
A2 at a glance
All values assume twelve-tone equal temperament at the international standard pitch of A4 = 440 Hz. In that system every semitone has the same size - a frequency ratio of 2^(1/12) - so A2 is exactly 440 × 2^(-24/12) Hz. Under alternative references the note shifts with the reference: at A4 = 432 Hz, A2 becomes 108.00 Hz.
A in every octave
| Note | Frequency | MIDI | Piano key |
|---|---|---|---|
| A0 | 27.50 Hz | 21 | 1 |
| A1 | 55.00 Hz | 33 | 13 |
| A2 ← | 110.00 Hz | 45 | 25 |
| A3 | 220.00 Hz | 57 | 37 |
| A4 | 440.00 Hz | 69 | 49 |
| A5 | 880.00 Hz | 81 | 61 |
| A6 | 1760.0 Hz | 93 | 73 |
| A7 | 3520.0 Hz | 105 | 85 |
Each octave doubles the frequency - the simplest relationship in music, and the reason notes an octave apart sound like “the same note, higher”.
Who plays A2
A2 is within the usual range of the piano, guitar, bass guitar, cello, double bass and trombone. Among voice types it falls in the usual range of baritone and bass.
- Piano: A0–C8
- Guitar (standard tuning): E2–E6
- Bass guitar (4-string): E1–G4
- Cello: C2–A5
- Double bass: E1–G4
- Trombone (tenor): E2–F5
- Baritone: A2–A4
- Bass voice: E2–E4
Ranges are approximate: they are the commonly cited sounding (concert) pitches, and real ranges vary by player, instrument, tuning and repertoire. Guitar, bass guitar and double bass are written an octave higher than they sound; B♭ clarinet and trumpet are written a whole tone higher.
Neighboring notes
One semitone down is G♯2 at 103.83 Hz; one semitone up is A♯2 at 116.54 Hz. Need a frequency between notes, or a different waveform? The tone generator plays anything from 20 Hz to 20 kHz; the note ↔ frequency converter does the math both directions, and the chromatic tuner listens to your instrument and shows the offset in cents.