Chord reference · four-note chord
Cadd9 chord (C added ninth)
The Cadd9 chord contains 4 written tones: C, E, G, D. Its interval formula is 1–3–5–9.
Cadd9 chord notes and interval formula
The formula 1–3–5–9 means the chord is measured from C using the root, major third, perfect fifth, and major ninth. In semitone numbers from the root, the pattern is 0–4–7–14. The missing flat seventh is why this is written add9, not simply 9.
| Degree | Interval | Semitones | Note |
|---|---|---|---|
| 1 | Root | 0 | C |
| 3 | Major Third | 4 | E |
| 5 | Perfect Fifth | 7 | G |
| 9 | Major Ninth | 14 | D |
How to play Cadd9 on piano
Start with the notes in root position from low to high: C – E – G – D. Right hand 1–2–3–5; left hand 5–3–2–1 is a useful starting point, but black-key combinations and melodic movement may make another fingering more comfortable.
For a cleaner accompaniment, place the root in the left hand and play the remaining tones in the right. With extended chords, keep the third and seventh because they identify the chord quality most clearly.
How to play Cadd9 on guitar
Try the shape x-3-0-0-3-0 in standard tuning, read from low E to high E. The sounding-string details are: E mute; A fret 3: C; D open: D; G open: G; B fret 3: D; E open: E. Keep every note clear and release pressure from strings marked “x.”
This is one voicing, not the only correct shape. The chord remains Cadd9 whenever the essential pitch classes are present; doubling, omission, and bass-note choice change the voicing rather than the basic chord name.
Cadd9 inversions and slash chords
Inversions keep the same notes but place a different chord tone in the bass. They are useful for smoother bass lines, compact keyboard movement, and alternative guitar voicings.
| Position | Symbol | Notes low to high | Bass |
|---|---|---|---|
| Root position | Cadd9 | C – E – G – D | C |
| 1st inversion | Cadd9/E | E – G – D – C | E |
| 2nd inversion | Cadd9/G | G – D – C – E | G |
| 3rd inversion | Cadd9/D | D – C – E – G | D |
What Cadd9 sounds like and where it fits
The C added ninth chord is major with an open upper color. An add9 chord keeps the major triad and adds the ninth without adding a seventh. That distinction matters: an add9 chord is usually more consonant than a dominant ninth chord.
Cadd9 compared with similar chords
Small interval changes create different chord names. Use this table to avoid confusing Cadd9 with nearby structures.
| Chord | Quality | Formula | Notes |
|---|---|---|---|
| C | Major | 1–3–5 | C, E, G |
| C9 | Dominant Ninth | 1–3–5–♭7–9 | C, E, G, B♭, D |
| C6/9 | Major Sixth/Ninth | 1–3–5–6–9 | C, E, G, A, D |
Frequently asked questions
What notes are in the Cadd9 chord?
The Cadd9 chord contains C, E, G, D. Its interval formula is 1–3–5–9.
How do you play Cadd9 on piano?
Play C, E, G, D together. A practical root-position fingering is right hand 1–2–3–5; left hand 5–3–2–1; adjust the fingering to your hand and musical context.
How do you play Cadd9 on guitar?
One compact standard-tuning shape is x-3-0-0-3-0 from the low E string to the high E string. An “x” means mute that string.
What does the symbol Cadd9 mean?
The root is C. The suffix add9 identifies a added ninth structure with the formula 1–3–5–9.
How many inversions does Cadd9 have?
A 4-note chord has 4 closed-position arrangements when every chord tone is retained: root position plus 3 inversions. Extended practical voicings may omit notes.