9th Chord Formula: Dominant, Major & Minor 9th

The standard 9th chord formula is 1–3–5–♭7–9. A plain “9” chord symbol means a dominant ninth chord: a major triad with a minor seventh and a major ninth. For example, C9 contains C, E, G, B♭, and D.

The symbol matters because “ninth chord” can describe several related chord qualities:

Chord quality	Formula	Notes with C as root
C9	1–3–5–♭7–9	C–E–G–B♭–D
Cmaj9	1–3–5–7–9	C–E–G–B–D
Cm9	1–♭3–5–♭7–9	C–E♭–G–B♭–D

The third determines whether the chord is major or minor, while the seventh separates dominant 9 from major 9. If seventh-chord construction is unfamiliar, compare the formulas for dominant seventh chords before adding the ninth.

A ninth is a compound interval, one scale step beyond the octave. D is the ninth above C, although it is the second scale degree within the first octave.

How Do You Build a Ninth Chord?

Build a ninth chord by starting with the appropriate seventh chord and adding the ninth above its root. The chord is theoretically formed by stacking thirds: root, third, fifth, seventh, and ninth.

Begin with the correct seventh chord

For a dominant ninth, start with a dominant seventh chord. C7 is C–E–G–B♭; adding D produces C9. The interval formula changes predictably for other qualities:

• Dominant 9: 1–3–5–♭7–9
• Major 9: 1–3–5–7–9
• Minor 9: 1–♭3–5–♭7–9
• Minor-major 9: 1–♭3–5–7–9

The major seventh formula explains why Cmaj9 uses B natural, while the minor seventh formula shows why Cm9 combines E♭ with B♭.

Add the ninth from the major scale

The unaltered ninth has the same letter name and pitch class as the major second. To find it, count nine letter names inclusively from the root or locate scale degree 2 in the root’s major scale. From C, the count C–D–E–F–G–A–B–C–D ends on D.

Correct spelling matters. The ninth of F♯ is G♯, not A♭, because F–G supplies the required letter relationship. Thinking in scale degrees, as explained in how chords are built, works in every key.

Keep the seventh in a complete ninth chord

A complete ninth chord includes a seventh. C–E–G–D is Cadd9, not C9, because it adds D directly to a C major triad without B♭. This distinction affects both the chord symbol and its harmonic function.

What Notes Are in Dominant 9th Chords in Every Key?

Each dominant ninth chord contains a major third, perfect fifth, minor seventh, and major ninth above its root. The following table uses practical chord spellings so each scale degree has the correct letter name.

Chord	Notes
C9	C–E–G–B♭–D
D♭9	D♭–F–A♭–C♭–E♭
D9	D–F♯–A–C–E
E♭9	E♭–G–B♭–D♭–F
E9	E–G♯–B–D–F♯
F9	F–A–C–E♭–G
G♭9	G♭–B♭–D♭–F♭–A♭
G9	G–B–D–F–A
A♭9	A♭–C–E♭–G♭–B♭
A9	A–C♯–E–G–B
B♭9	B♭–D–F–A♭–C
B9	B–D♯–F♯–A–C♯

Enharmonic chords can sound identical in equal temperament while being spelled differently. D♭9 and C♯9, for example, use the same piano keys but represent different written relationships. Choose the spelling that fits the key and progression rather than mixing sharps and flats arbitrarily.

How Do 9, Maj9, Min9, Add9, 7♭9, and 7♯9 Differ?

These symbols differ in the quality of the third, seventh, or ninth. A plain 9 uses a major third, minor seventh, and unaltered ninth; “maj” changes the seventh, “m” changes the third, and an accidental directly before 9 alters only the ninth.

Symbol	Formula	C-root notes	Defining feature
C9	1–3–5–♭7–9	C–E–G–B♭–D	Dominant seventh plus ninth
Cmaj9	1–3–5–7–9	C–E–G–B–D	Major seventh
Cm9	1–♭3–5–♭7–9	C–E♭–G–B♭–D	Minor third
Cadd9	1–3–5–9	C–E–G–D	No seventh
C7♭9	1–3–5–♭7–♭9	C–E–G–B♭–D♭	Lowered ninth
C7♯9	1–3–5–♭7–♯9	C–E–G–B♭–D♯	Raised ninth

C9 implies B♭ even if a performer omits another optional tone; Cadd9 explicitly leaves the seventh out. A fuller explanation appears in the added-ninth chord guide.

An altered ninth does not turn the chord into a minor or major ninth chord. In C7♭9, D♭ is the altered extension while E and B♭ still establish a dominant chord. In C7♯9, D♯ is normally written as the raised ninth rather than E♭ because the symbol identifies an altered D.

Which Notes Can You Omit From a 9th Chord?

The perfect fifth is the most commonly omitted note from a 9th-chord voicing because it usually contributes less information than the third, seventh, or ninth. The root may also be omitted when a bass instrument clearly supplies it, but the chord’s defining tones should remain audible.

Preserve the defining tones

In C9, E identifies the major quality, B♭ supplies the dominant seventh, and D provides the ninth color. A compact rootless voicing containing E–B♭–D can still communicate C9 over a C bass. Removing B♭ instead would make the sound resemble Cadd9 and weaken its dominant identity.

Adapt the voicing to the instrument

On piano, the left hand might play C and B♭ while the right hand plays E and D; G can be omitted. Wider spacing in the lower register prevents the harmony from becoming muddy.

On guitar, five pitch classes may be awkward. A shape can double a tone or exclude the fifth while preserving the third, seventh, and ninth. These choices are covered in extended guitar chord voicings, while common chord-symbol conventions distinguish an omission from a differently named chord.

Omission does not change the theoretical formula. The formula describes the harmony implied by the symbol; a voicing describes the notes and order a musician actually plays.

How Are Ninth Chords Used in Progressions?

Dominant 9 chords commonly create tension that resolves down a fifth to a tonic chord. Major 9 and minor 9 chords are usually more stable color chords, although their function always depends on the key, melody, and surrounding harmony.

Dominant 9 resolution

In F major, C9 can resolve to Fmaj7. B♭ can move down to A, E up to F, and D to C. This stepwise motion gives the progression direction.

A dominant 9 can also intensify a secondary dominant. In C major, A9 can lead to Dm because A functions as the dominant of D. Understanding secondary dominant movement helps explain why a chord containing C♯ can sound logical even though C♯ is outside the C-major scale.

Major 9 and minor 9 color

Cmaj9 has a spacious, settled quality because it combines the major seventh and major ninth without dominant-seventh tension. Dm9 works naturally as the ii chord in C major: D–F–A–C–E uses only notes from the key.

Good voice leading is usually more useful than moving one fixed shape around. Keep common tones, move remaining notes by the smallest practical interval, and avoid crowding several close notes in a low register. These choices preserve the ninth’s color while keeping the progression clear.

Frequently Asked Questions

Does a 9th chord always contain a seventh?

A complete 9th chord includes or implies a seventh. A plain dominant 9 contains a minor seventh, maj9 contains a major seventh, and m9 normally contains a minor seventh; a triad with a ninth but no seventh is called add9.

What does a plain 9 mean in a chord symbol?

A plain 9 means a dominant ninth chord with the formula 1–3–5–♭7–9. C9 therefore contains C, E, G, B♭, and D.

What is the difference between C9 and Cmaj9?

C9 contains B♭, giving it a minor seventh and dominant function. Cmaj9 contains B natural, so its formula is 1–3–5–7–9 and its sound is not a dominant ninth.

Is a 9th chord the same as an add9 chord?

No. C9 includes the minor seventh B♭, while Cadd9 contains only C, E, G, and D; add9 means that the ninth is added to a triad without an implied seventh.

Which note can be omitted from a ninth chord?

The perfect fifth is usually the safest note to omit because the third, seventh, and ninth communicate more of the chord’s identity. The root can also be omitted when a bass player or another instrument clearly provides it.

What is the difference between a major ninth chord and a ♭9 chord?

A major ninth chord, such as Cmaj9, has a major seventh and an unaltered ninth: C–E–G–B–D. C7♭9 is a dominant seventh chord with a lowered ninth: C–E–G–B♭–D♭.