A♭ dominant ninth (A♭9) chord on piano

The A♭ dominant ninth chord (A♭9) is a dominant ninth chord (a dominant seventh plus a major ninth), made of five notes: A♭ – C – E♭ – G♭ – B♭. The same chord with a different spelling: G♯ dominant ninth (G♯9).

Full chord: A♭3 – C4 – E♭4 – G♭4 – B♭4

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What the A♭9 chord sounds like

A dominant ninth is a dominant seventh with an added major ninth. A fuller, fatter dominant sound – a staple of funk, soul and blues.

Notes of the A♭9 chord

Degree	Note	Interval from the root
1	A♭	root
3	C	major third (4 semitones)
5	E♭	perfect fifth (7 semitones)
7	G♭	minor seventh (10 semitones)
9	B♭	major second (2 semitones)

Piano voicings

Chords with five or more notes are rarely played in one hand: the left hand takes the root, the right hand the colour notes. The fifth (and in an eleventh chord the third) is often left out.

Full chord

A♭3 – C4 – E♭4 – G♭4 – B♭4

Two-hand voicing

A♭2 – C4 – G♭4 – B♭4 – E♭5

Which keys is it in?

The A♭9 chord is built from the notes of these keys (for minor keys, both the natural and the harmonic minor are considered):

D♭ major: V9 (dominant)
B♭ minor: VII9

Similar chords and substitutes

If A♭9 is too hard, or you want a different colour in the same spot, these chords are worth a try.

Substitutes (by function)

D7 – tritone substitute: the same third and seventh, swapped – a jazz favourite
Cdim7 – diminished seventh on the third: a common stand-in for the dominant
A♭7 – a simpler dominant
A♭7sus4 – suspended dominant, less tense
C♯ – where it resolves (V → I)

Simpler versions

A♭7 – all 4 of its notes are in this chord
A♭add9 – all 4 of its notes are in this chord
A♭ – all 3 of its notes are in this chord
A♭sus2 – all 3 of its notes are in this chord

Richer versions

A♭11 – the same chord plus 1 colour note
A♭13 – the same chord plus 1 colour note

Frequently asked questions

What notes are in the A♭9 chord?

A♭, C, E♭, G♭, B♭. The root is A♭; the intervals of the other notes from the root: major third, perfect fifth, minor seventh, major second.

How do I play the A♭9 chord on piano?

Play the root with your left hand and the colour notes (third, seventh, ninth) with your right hand – the two-hand voicing above. Stacking all 5 notes in one hand is possible but sounds crowded.

How is the A♭9 chord written?

The chord symbol is A♭9 (also written Ab9), and its full name is A♭ dominant ninth.