Extended Chords

Ninths, elevenths, thirteenths

Keep stacking thirds above a seventh chord and you get 9, then 11, then 13. Beyond the thirteenth you are back at the root, so the stack ends there — a thirteenth chord in full contains all seven notes of a scale.

Nobody plays seven notes. A working C13 is five: root, third, seventh, ninth and thirteenth. The fifth goes first because it carries no information, and the eleventh is usually left out too.

The eleventh problem

Over a major third, a natural eleventh sits a semitone away and clashes. This is why Cmaj11 is almost never played in full, why C11 is played without its third at all, and why C13 quietly drops the eleventh.

Minor chords have no such trouble: the interval there is a whole tone, so Cm11 and Cm13 are played complete and often. The difficulty is not the extension itself but its neighbour.

Upper structures

The fastest way to build these chords is to stop counting degrees. Over C7, a D major triad gives you the ninth, sharp eleventh and thirteenth at once; a D minor triad over Cm7 gives the ninth, eleventh and thirteenth.

Pianists and arrangers work this way constantly — left hand on the root and the tritone, right hand playing a familiar triad from somewhere else. It is the same chord, reached in a fraction of the time.

On the guitar

Six strings and four usable fingers force the same choices. C9 is x32330, C13 is x32335, Cm9 is x31333 — all of them missing at least one theoretical note, and none of them sounding incomplete.

Two open shapes are worth learning immediately because they are easier than the chords they extend: Cmaj9 is x30000, and Cadd9 is x32033. Extended does not have to mean difficult.

When they belong

In slow to medium tempos and in music that wants colour rather than drive. A ballad, a bossa, a film cue, a soul progression — anywhere the harmony has time to be heard.

In a fast, dense arrangement they blur. Five notes need space, and a plain seventh chord will often say more. The choice is about texture, not sophistication.

Frequently asked questions