Ninth chord
A ninth chord arises when you stack a further third on a seventh chord. Above the root then lies a ninth, an interval of an octave plus a second. The chord consists of five different notes.
- Construction
- seventh chord plus a third
- Notes
- five: root, third, fifth, seventh, ninth
- Major ninth
- 14 semitones above the root
- Minor ninth
- 13 semitones above the root
- Commonest form
- on the dominant
Five notes on one root
A triad consists of two stacked thirds, a seventh chord of three. If you stack a fourth third on top, a ninth arises above the root. It is a second, placed an octave higher. The ninth chord thus has five notes: root, third, fifth, seventh and ninth. In C major on the dominant G these are G, B, D, F and A.
G9 in C major: five notes, major ninth
On the left all five notes: G–B–D–F–A. On the right the four-part form without the fifth: G–B–F–A. The ninth A lies far above the root G, more than an octave away. That is what matters for the sound.
Major and minor ninth
On the left in major with a major ninth (A), on the right in minor with a minor ninth (A♭). The marked chord is the dominant ninth chord of C minor. It sounds more tense and darker.
Without the root: the seventh-chord frame above
If you leave out the root G in both ninth chords, seventh chords above the leading tone B remain: on the left the half-diminished (B–D–F–A), on the right the fully diminished (B–D–F–A♭).
In the glossary: Seventh chord · Ninth · Dominant
Major or minor
The ninth can be major or minor. The major ninth lies 14 semitones above the root, the minor ninth 13. The difference is small but changes the sound considerably. On the dominant the major ninth is usually used in major, the minor ninth in minor. The dominant seventh chord with a major ninth sounds full and colourful, with a minor ninth more tense and darker. In functional theory one speaks of the dominant seventh-ninth chord.
The first three chords are in C major: the seventh chord, the same with the ninth, and the resolution to C. Then follows the minor variant with the minor ninth, A♭, and the close to C minor. The ninth resolves downwards, in the example to the G of the target chord.
Five notes, four voices: what gets left out?
In four-part writing five notes cannot all be accommodated. It is usual to leave out the fifth, since it contributes least to the effect. If instead you leave out the root and keep the fifth, a seventh chord above the leading tone remains. With the dominant ninth chord that is the half-diminished seventh chord with a major ninth, the fully diminished one with a minor ninth. This reading explains why both chords have a dominant effect and resolve into the tonic. More on the fully diminished seventh chord can be found in the article The diminished seventh.
| Form | Notes above G | Sound |
|---|---|---|
| Dominant seventh chord | G–B–D–F | tense, still without the ninth |
| with major ninth (major) | G–B–D–F–A | full and colourful |
| with minor ninth (minor) | G–B–D–F–A♭ | more tense, darker |
| without root, major ninth | B–D–F–A | half-diminished seventh chord |
| without root, minor ninth | B–D–F–A♭ | fully diminished seventh chord |
Position matters
For the sound the position decides. The ninth should lie far above the root, at least an octave above. If you put it in close position directly next to the root, it turns into a harsh rubbing second.
Where ninth chords are found
In classical harmony teaching the ninth mostly appears as a suspension: it is prepared and resolves downwards. As an independent chord the ninth chord caught on mainly in the late 19th century. Composers of Impressionism often use ninth chords as tone colour without resolving them. In jazz ninths are among the usual chord extensions. The chord symbol C9 there means C–E–G–B♭–D, a dominant seventh chord with a major ninth.
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Related terms
Seventh chordNinthDominantSuspensionTriadJazzImpressionismRoot position
Editor: Maik Krohm · reviewed on 3 October 2026
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