Learn › C#9 Chord on Piano (C Sharp Dominant 9th)
New Released in April 2026
C#9 Chord on Piano (C Sharp Dominant 9th)
C#9, the C sharp dominant 9th chord, is the dominant seventh C#7 plus the 9th, D#. Its notes on the piano are C#, E#, G#, B and D#. Its sound: rich and funky, a seventh chord with more colour.
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- MIDI keyboard
- Digital or acoustic piano
- Guitar
- Computer, phone or tablet
C#9 and E#m7b5
Above the root C# sit four notes that form E#m7b5: E# G# B D#. A pianist can play C# with the left hand and E#m7b5 with the right, and the result is C#9.
The formula of C#9
Every chord is a recipe of scale steps. For C#9 the recipe is 1 3 5 b7 9, counted from C#.
Start chord: C#7
| Note | Step | Interval | Keys from C# |
|---|---|---|---|
| C# | 1 | root | 0 |
| E# | 3 | major 3rd | 4 |
| G# | 5 | perfect 5th | 7 |
| B | b7 | minor 7th | 10 |
| D# | 9 | major 9th | 14 |
Ways to place C#9 on the keys
Learn them in pairs: root position first, then the one that keeps the most notes still.
Both hands: C# B E# G# D#
Rootless, 3rd on the bottom: E# G# B D#
Rootless, 7th on the bottom: B D# E# G#
Left hand alone: C# B
Which fingers
| Left hand | C# B | 5 1 |
|---|---|---|
| Right hand | E# G# D# | 1 2 4 |
Practise C#9 in four steps
- Say the notes out loud while you press them: C#, E#, G#, B and D#.
- Switch between C#7 and C#9 ten times without looking at your hand.
- Alternate root position and a rootless shape with the 3rd on the bottom, keeping shared notes still.
- Last, meet C#9 mixed with chords you already know, in an order you did not plan.
Come back to C#9 tomorrow: short daily sessions beat one long one.
Keys and moves for C#9
- C#9 is the V chord of F# major: it pulls home to F#.
- Many pianists play C#9 whenever C#7 appears, because the 9th makes the same pull sound richer.
Turn C#9 into a reflex
ChordRunner shows a chord symbol and you play it on a MIDI keyboard, a real piano through the microphone or the on-screen keys. Dominant 9ths appear in the later boss challenges, next to major and minor 9ths.
Play the demoCommon questions
What notes are in the C#9 chord?
C#9 has 5 notes: C#, E#, G#, B and D#. Formula 1 3 5 b7 9.
What is the difference between C#9 and C#7?
C#7 is C# E# G# B. To get C#9, add D# above the seventh.
Where is C#9 used?
C#9 is the V chord of F# major: it pulls home to F#. Many pianists play C#9 whenever C#7 appears, because the 9th makes the same pull sound richer.
Can I practise C#9 with a MIDI keyboard or a real piano?
Yes. In ChordRunner a USB MIDI keyboard is detected automatically, and an acoustic or digital piano works through the microphone. The game checks that C#, E#, G#, B and D# sound together.
Your instrument is the controller.
ChordRunner is a browser game that teaches piano and guitar chords: a chord appears on screen, you play it on a real instrument, and your runner jumps. MIDI keyboard or microphone, both work.
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