C9

Character: funky

Voicings

3 ways to play C9

Every voicing sits inside one of the five CAGED shapes, low to high on the neck, with its octave doublings in grey.

CC shape Root position C9

Frets x 3 2 3 3 0Notes C E B♭ DIntervals 1 3 ♭7 9Base triadC major, root position

The ♭7th takes the 5th’s string. The 9th gets a string of its own.

GG shape Root position C9

Frets 8 7 8 7 8 xNotes C E B♭ DIntervals 1 3 ♭7 9Base triadC major, root position

The ♭7th takes the 5th’s string. The 9th gets a string of its own.

EE shape Root position C9

Frets x x 10 9 11 10Notes C E B♭ DIntervals 1 3 ♭7 9Base triadC major, root position

The ♭7th takes the 5th’s string. The 9th gets a string of its own.

The rules

Start from a triad
Root, 3rd and 5th, stacked in thirds. The 3rd makes it major or minor; the 5th makes it diminished or augmented when it moves.
A third on top makes a 7th chord
A major 7th over a major triad is maj7, a ♭7 is a dominant 7. Over minor you get m7 or m(maj7); over diminished, m7♭5 or the °7, whose 7th is lowered twice.
Keep stacking for extensions
The 9th, 11th and 13th are the 2nd, 4th and 6th an octave up. Each one sits on the stack below it: a 9th chord holds a 7th, a 13th holds the 9th and 11th in theory.
On guitar, something has to give
Each extension takes the string of a triad note that matters less, usually the 5th, or gets a string of its own. The root and 3rd stay: they say what the chord is.

All the rules, with examples, in the guide to the chord library.

What notes are in C9?

C9 is spelled C E G B♭ D: C is the root, E is the 3rd, G is the 5th, B♭ is the ♭7th, D is the 9th.

What is the formula of C9?

1 3 5 ♭7 9. It is a C major triad with the ♭7th, 9th stacked on top.

How many ways can you play C9 on guitar?

This page shows 3 voicings of C9, filed under the five CAGED shapes and named by inversion, from the open position up to the 16th fret.