Tools / Chords / A 9th

A 9th chord on guitar (A9)

Also written A9 or A

A 9th is built from A, C♯, E, G and B. This advanced barre shape at the 4th fret needs a strong index barre and a clean high-e mute.

4th fret5-4-5-4-5-×

Positions on the neck1 of 5

How it’s built

A1Root

C♯3Major 3rd

E5Perfect 5th

G♭7Minor 7th

B99th

Formula 1, 3, 5, ♭7, 9

Positions on the neck1 of 5

Inversions

The same three notes, with a different one in the bass.

Root positionA–C♯–E–G–BA9Bass A

First inversionC♯–E–G–B–AA9/C♯Bass C♯

Second inversionE–G–B–A–C♯A9/EBass E

Third inversionG–B–A–C♯–EA9/GBass G

Fourth inversionB–A–C♯–E–GA9/BBass B

Why it sounds like that

A 9th stacks a major triad (1, 3, 5) with a minor seventh and a major ninth: 1, 3, 5, ♭7, 9. The ♭7–9 combination gives the chord its dominant pull. Compare it with A 7th, which stops at the ♭7 and sounds less colourful.

What goes wrong with A 9th?

Letting the index barre collapse so the G string buzzes at fret 4.
Allowing the high e string to ring open, which adds an unwanted E above the chord.
Placing the ring finger on the G string instead of the D string, losing the fifth.

When to use it

A 9th works as the dominant in D major, where it can replace A major in progressions like D–G–A–D (I–IV–V–I). It suits blues, funk and jazz-rock comping.

Changing to and from A 9th

Move to G 9th by sliding the shape down two frets to the 2nd fret.
Move to B♭ 9th by sliding the shape up one fret to the 5th fret.

Which voicing to use

The 4th fret and 5th fret voicings both put A in the bass, but the 5th fret version adds the ninth on top for a brighter sound. Use the A9/C♯ inversion when you want the third in the bass for a smoother voice-leading.

How do you play an A 9th chord on guitar?

4th fret

Barre● On the diagram

A 9th is played at the 4th fret as 5 4 5 4 5 ×: barre your index finger across fret 4, middle finger on the low E string at fret 5, ring finger on the D string at fret 5 and pinky finger on the B string at fret 5. The high e string stays muted.

Tip — The index barre must fret the A string and the G string cleanly while the pinky reaches fret 5 on the B string.

String-by-string breakdown

String	Fret	Finger	Note
6 (E)	5	2	A (1)
5 (A)	4	1 (barre)	C♯ (3)
4 (D)	5	3	G (♭7)
3 (G)	4	1 (barre)	B (9)
2 (B)	5	4	E (5)
1 (e)	muted	—	—

5th fret

Barre

A 9th is played at the 5th fret as 5 7 5 6 5 7: barre your index finger across fret 5, ring finger on the A string at fret 7, middle finger on the G string at fret 6 and pinky finger on the high e string at fret 7.

String-by-string breakdown

String	Fret	Finger	Note
6 (E)	5	1 (barre)	A (1)
5 (A)	7	3	E (5)
4 (D)	5	1 (barre)	G (♭7)
3 (G)	6	2	C♯ (3)
2 (B)	5	1 (barre)	E (5)
1 (e)	7	4	B (9)

A9/C♯ inversion · fret 4

Barre

A 9th is played at the 4th fret as × 4 5 4 5 5: barre your index finger across fret 4, middle finger on the D string at fret 5, ring finger on the B string at fret 5 and pinky finger on the high e string at fret 5. The low E string stays muted.

String-by-string breakdown

String	Fret	Finger	Note
6 (E)	muted	—	—
5 (A)	4	1 (barre)	C♯ (3)
4 (D)	5	2	G (♭7)
3 (G)	4	1 (barre)	B (9)
2 (B)	5	3	E (5)
1 (e)	5	4	A (1)

A9/C♯ inversion · fret 7

Barre

A 9th is played at the 7th fret as 9 7 7 9 8 7: barre your index finger across fret 7, ring finger on the low E string at fret 9, pinky finger on the G string at fret 9 and middle finger on the B string at fret 8.

String-by-string breakdown

String	Fret	Finger	Note
6 (E)	9	3	C♯ (3)
5 (A)	7	1 (barre)	E (5)
4 (D)	7	1 (barre)	A (1)
3 (G)	9	4	E (5)
2 (B)	8	2	G (♭7)
1 (e)	7	1 (barre)	B (9)

A9/C♯ inversion · fret 9

Barre

A 9th is played at the 9th fret as 9 10 9 9 10 9: barre your index finger across fret 9, ring finger on the A string at fret 10 and pinky finger on the B string at fret 10.

String-by-string breakdown

String	Fret	Finger	Note
6 (E)	9	1 (barre)	C♯ (3)
5 (A)	10	3	G (♭7)
4 (D)	9	1 (barre)	B (9)
3 (G)	9	1 (barre)	E (5)
2 (B)	10	4	A (1)
1 (e)	9	1 (barre)	C♯ (3)

Common questions

How is A 9th written?

A 9th is written as A9. The symbol A9 always means a dominant ninth chord with a minor seventh and a major ninth.

What is the difference between A 9th and A add 9?

A 9th includes the minor seventh G, while A add 9 is a plain A major triad with the ninth B added and no seventh. The add 9 sounds more open and less bluesy.

Why does the A9/C♯ inversion have a different bass note?

The A9/C♯ inversion places the third, C♯, in the bass instead of the root A. This creates a smoother stepwise bass line when moving between chords in D major.

String

Fret

Finger

Note

6 (E)

A (1)

5 (A)

1 (barre)

C♯ (3)

4 (D)

G (♭7)

3 (G)

1 (barre)

B (9)

2 (B)

E (5)

1 (e)

muted

—

String

Fret

Finger

Note

6 (E)

1 (barre)

A (1)

5 (A)

E (5)

4 (D)

1 (barre)

G (♭7)

3 (G)

C♯ (3)

2 (B)

1 (barre)

E (5)

1 (e)

B (9)

String

Fret

Finger

Note

6 (E)

muted

—

5 (A)

1 (barre)

C♯ (3)

4 (D)

G (♭7)

3 (G)

1 (barre)

B (9)

2 (B)

E (5)

1 (e)

A (1)

String

Fret

Finger

Note

6 (E)

C♯ (3)

5 (A)

1 (barre)

E (5)

4 (D)

1 (barre)

A (1)

3 (G)

E (5)

2 (B)

G (♭7)

1 (e)

1 (barre)

B (9)

String

Fret

Finger

Note

6 (E)

1 (barre)

C♯ (3)

5 (A)

G (♭7)

4 (D)

1 (barre)

B (9)

3 (G)

1 (barre)

E (5)

2 (B)

A (1)

1 (e)

1 (barre)

C♯ (3)