Also written Aadd9, A or A Add 9th
A add 9 is built from A, C♯, E, and B. This advanced voicing sits high on the neck, demanding a wide finger stretch.
The same three notes, with a different one in the bass.
A add 9 uses the formula 1, 3, 5, 9. The major 2nd between A and B adds the ninth, while the major 3rd from A to C♯ keeps the major quality. Compare it with A major, which omits the ninth.
A add 9 works as the tonic in A major, especially in the I–IV–V–I progression: A major–D major–E major–A major. Use it in rock, pop, and funk lines where the ninth adds brightness. It also fits over A major and A 5th chords.
The default voicing places B in the bass, creating a softer, less root-oriented sound. Use this inversion when the bass line needs to move stepwise or when another instrument covers the root.
A add 9 is played at the 6th fret as 7 7 7 6: middle finger on the E string at fret 7, ring finger on the A string at fret 7, pinky finger on the D string at fret 7 and index finger on the G string at fret 6.
Tip — The stretch between the index finger on the 6th fret and the pinky on the 7th fret of the D string is wide.
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 7 | 2 | B (9) |
| 3 (A) | 7 | 3 | E (5) |
| 2 (D) | 7 | 4 | A (1) |
| 1 (G) | 6 | 1 | C♯ (3) |
A add 9 includes the ninth, B, which A major omits. The added note creates a more colorful, suspended-like quality while retaining the major third.
A add 9 is diatonic to B natural minor and F♯ natural minor. In those keys it functions as a borrowed major chord, often used for modal interchange.
Practice moving between A add 9 and A major slowly, focusing on keeping the fingers close to the fretboard. Gradually increase speed while maintaining clean note separation.