Learn › C#add9 Chord on Piano (C Sharp Add 9)
New Released in April 2026
C#add9 Chord on Piano (C Sharp Add 9)
The C sharp add 9 chord (C#add9) uses the piano keys C#, E#, G# and D#: the major triad C# plus the 9th, D#, with no seventh in between. In one phrase: clear and sparkling, the plain triad with one extra colour.
No account, no download. The demo has limited content. Advanced features are in ChordRunner Premium.
- MIDI keyboard
- Digital or acoustic piano
- Guitar
- Computer, phone or tablet
Where your hand goes for C#add9
Each picture is still C#add9. Move only the notes that must move.
Root position: C# D# E# G#
1st inversion: E# G# C# D#
2nd inversion: G# C# D# E#
Fingering
| Right hand | C# D# E# G# | 1 2 3 5 |
|---|---|---|
| Left hand | C# D# E# G# | 5 4 3 1 |
The chord hiding inside C#add9
Take C#sus2 (C# D# G#) and add the third E#: you have C#add9. That is why C#add9 still sounds major, while C#sus2 does not.
Building C#add9 from C#
Start from C#, which you may already know, and change one thing: add D#, the 9th, an octave plus a whole step above C#.
Start chord: C#
| Note | Step | Interval | Keys from C# |
|---|---|---|---|
| C# | 1 | root | 0 |
| E# | 3 | major 3rd | 4 |
| G# | 5 | perfect 5th | 7 |
| D# | 9 | major 9th | 14 |
Make C#add9 automatic
- Find C#, then add the other notes one at a time: C#, E#, G# and D#.
- Play C#, then C#add9, then C# again, and hear what the 9th adds on top.
- Try C#add9 in 1st inversion, the position that sits closest to your last chord.
- Then test it in random order among other chords: recall under time pressure is what sticks.
Five minutes a day is enough to make C#add9 feel easy.
Where C#add9 is used
- C#add9 fits wherever C# fits: C# major, Ab major (as Db) and F# major.
- Pop and worship songs use it in place of plain C# to make a simple progression sound fuller.
How C#add9 differs from the chords around it
One or two notes change the whole colour. Click a chord to open its page.
Train C#add9 with ChordRunner
Chord symbols arrive one after another and the game checks every note you play, with MIDI or the microphone. Add9 chords come in the level "Sixth & Add Chords".
Play the demoCommon questions
What is C#add9 on the piano?
C#add9 is the C sharp add 9 chord: C#, E#, G# and D#, the major triad C# plus the 9th, D#, with no seventh in between.
Is C#add9 the same as C#sus2?
No. C#sus2 has no third, C#add9 adds E#, and that one note makes C#add9 sound major.
Where is C#add9 used?
C#add9 fits wherever C# fits: C# major, Ab major (as Db) and F# major. Pop and worship songs use it in place of plain C# to make a simple progression sound fuller.
Can I practise C#add9 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# 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.
Try the demoKeep learning
Piano Chord Chart: Every Chord in All 12 Keys
Piano chord chart with the notes of 288 chords: major, minor, 7ths, 9ths, sus and more in all 12 keys. Click a…
Extended Chords: 9ths, 11ths, 13ths
How 9th, 11th and 13th chords are built, what to leave out, and a game that drills every extension on your MID…
C#9 Chord on Piano (C Sharp Dominant 9th)
The C sharp dominant 9th chord C#9 on piano: C# E# G# B D#, built from C#7, compared with nearby chords.…
C#maj9 Chord on Piano (C Sharp Major 9th)
C#maj9 chord on piano: notes C# E# G# B# D#, formula 1 3 5 7 9, fingering, E#m7 and where it is used.…
C#m9 Chord on Piano (C Sharp Minor 9th)
How to play the C#m9 chord (C sharp minor 9th) on piano: C# E G# B D#, rootless voicings, fingering and the ke…
Chord Training That Feels Like a Game
Interactive chord training in your browser. Play major, minor, 7th and extended chords on a MIDI keyboard or a…