C♯ dominant ninth (C♯9) chord on piano

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

Full chord: C♯4 – E♯4 – G♯4 – B4 – D♯5

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What the C♯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 C♯9 chord

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

C♯4 – E♯4 – G♯4 – B4 – D♯5

Two-hand voicing

C♯3 – E♯4 – B4 – D♯5 – G♯5

Which keys is it in?

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

F♯ major: V9 (dominant)
D♯ minor: VII9

Similar chords and substitutes

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

Substitutes (by function)

G7 – tritone substitute: the same third and seventh, swapped – a jazz favourite
Fdim7 – diminished seventh on the third: a common stand-in for the dominant
C♯7 – a simpler dominant
C♯7sus4 – suspended dominant, less tense
F♯ – where it resolves (V → I)

Simpler versions

C♯7 – all 4 of its notes are in this chord
C♯add9 – all 4 of its notes are in this chord
C♯ – all 3 of its notes are in this chord
C♯sus2 – all 3 of its notes are in this chord

Richer versions

C♯11 – the same chord plus 1 colour note
C♯13 – the same chord plus 1 colour note

Frequently asked questions

What notes are in the C♯9 chord?

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

How do I play the C♯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 C♯9 chord written?

The chord symbol is C♯9 (also written C#9), and its full name is C♯ dominant ninth.