A9 chord
A9 is A, C♯, E, G and B: 1–3–5–♭7–9 built on A. See and hear it on all three instruments below.
On guitar
5-4-2-0-0-0 · open · medium
- Notes
- A · C♯ · E · G · B
- Formula
- 1 · 3 · 5 · ♭7 · 9
- First shape
- 5-4-2-0-0-0
A9 on guitar: every shape, finger by finger
On piano
root position · A–C♯–E–G–B · right hand 1-2-3-4-5
- Notes
- A · C♯ · E · G · B
- Formula
- 1 · 3 · 5 · ♭7 · 9
A9 on piano: fingering and inversions
On ukulele
2-1-3-2 · movable · medium
- Notes
- A · C♯ · E · G · B
- Formula
- 1 · 3 · 5 · ♭7 · 9
- First shape
- 2-1-3-2
Changing out of A9
The moves below are the ones you'll meet most, shown for guitar and piano.
- A9 → D (dominant, pulls to the chord a fifth below)
Guitar: A9 (5-4-2-0-0-0) to D (x-x-0-2-3-2): the index finger slides across to the G string at the same fret, move the middle finger to the high E string, 2nd fret, the ring finger goes to the B string, 3rd fret. No finger can stay, so practice lifting all of them together and landing the new shape as a unit. A carries over from one chord to the other.
Piano: A9 to D: play D in 2nd inversion (A–D–F♯) and A stays under the same finger, while C♯ moves up to D and G down to F♯. D - A9 → Dmaj7 (I in D major)
Guitar: A9 (5-4-2-0-0-0) to Dmaj7 (x-x-0-2-2-2): the index finger slides across to the G string at the same fret, your middle finger lands on the B string, 2nd fret, move the ring finger to the high E string, 2nd fret. No finger can stay, so practice lifting all of them together and landing the new shape as a unit. Listen for A and C♯, which stay put while the rest moves.
Piano: A9 to Dmaj7: play Dmaj7 in 2nd inversion (A–C♯–D–F♯) and A and C♯ stay under the same fingers, while E moves down to D and G down to F♯. Dmaj7 - A9 → Bm7 (vi in D major)
Guitar: A9 (5-4-2-0-0-0) to Bm7 (x-2-0-2-0-2): the index finger slides across to the A string at the same fret, the middle finger goes to the G string, 2nd fret, move the ring finger to the high E string, 2nd fret. Nothing carries over, so drill it slowly, lifting and landing all fingers at once. Shared notes: A and B.
Piano: A9 to Bm7: play Bm7 in 1st inversion (D–F♯–A–B) and B stays under the same finger, while C♯ moves up to D, G down to F♯ and G up to A. Bm7
Guitar with a capo: capo 5, E9 shape.
How A9 is built
A9 is a dominant ninth: A7 with the ninth on top. It has the pull of a seventh chord with a funkier, fuller color, and like A7 it leans toward D.
Start on A, count 4 half steps up to C♯, 3 half steps up to E, 3 half steps up to G then 4 half steps up to B.
| Note | Role | Half steps | Hear it |
|---|---|---|---|
| A | root | 0 | |
| C♯ | major third | 4 | |
| E | perfect fifth | 7 | |
| G | minor seventh | 10 | |
| B | ninth | 14 |
Keys and progressions with A9
A9 isn't a chord of any major or natural minor key, so it usually appears as a passing or borrowed chord.
Chords close to A9
- A9 is A7 plus B. A7
Chords that share most of their notes with A9: C♯m7♭5, Em6, A7, Aadd9, C♯dim, Em.
Every A chord
A9 chord: questions
What notes are in the A9 chord?
A, C♯, E, G and B. A9 is built 1–3–5–♭7–9 from A: C♯ is the major third, E is the perfect fifth, G is the minor seventh and B is the ninth.
How do you play A9 on guitar?
The usual shape is 5-4-2-0-0-0 (open). All 3 guitar shapes.
How do you play A9 on piano?
Play A, C♯, E, G and B with right-hand fingers 1-2-3-4-5. A sits between the last two black keys of the three. Inversions and left hand.
How do you play A9 on ukulele?
2-1-3-2 in standard GCEA tuning. More ukulele shapes.
What key is A9 in?
A9 isn't a chord of any major or natural minor key, so it usually appears as a passing or borrowed chord.
What's the difference between A9 and A7?
A9 is A7 plus B.
All three instruments are drawn and played from A, C♯, E, G and B by the same engine. Updated September 2026.