C Add 9 Chord

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Formula R – 9 – 3 – 5

Summary

C Add 9 is built from the notes C, D, E, G. The interval from C to D is a major 2nd (2 semitones), from C to E is a major 3rd (4 semitones), from C to G is a perfect 5th (7 semitones).

The add9 takes a complete major triad and drops in a shimmering 9th on top — no 7th involved. It's bright, sophisticated, and instantly recognizable. If you've ever played a Cadd9 or Gadd9 in open position, you already know this sound.

Theory

Formed by taking a complete major triad (R, 3, 5) and adding a major 9th — the same note as the 2nd, but placed an octave above the root. The crucial distinction from a standard 9th chord is that the add9 omits the 7th entirely, keeping the underlying major harmony clean and uncomplicated. This makes it feel more like a colorful major chord than a jazz extension.

On the guitar

Cadd9 and Gadd9 are two of the most popular open chords in all of guitar playing. Cadd9 is easily formed by taking a standard open C shape and adding your pinky on the 1st string, 3rd fret. These shapes are staples of acoustic guitar because they ring out beautifully with open strings and add a lush, full quality to basic strumming patterns.

Advanced

The add9 is a fantastic default replacement for plain major chords in acoustic and pop contexts — it adds color without changing the harmonic function. In the CAGED system, the C-shape and G-shape add9 voicings are the most practical. Try using add9 on the 1st and 4th chords of a progression for instant richness, while keeping the 5th chord as a plain major or dominant 7th for contrast.

Piano