Add Chords

What add actually means

Cadd9 is C, E, G and D — a major triad plus a ninth. There is no B♭, and that is the difference from C9, which is a dominant chord with a seventh in it. The word add is there to say that nothing else came along.

The same logic gives add2, add11 and add♯11, and the minor versions of each. Sixth chords belong here too: C6 adds a sixth and no seventh, and C6/9 adds both a sixth and a ninth.

Register decides the name

Cadd9 and Cadd2 contain the same pitch classes. The difference is where the added note sits: next to the root it rubs, an octave up it just brightens. The symbol tells the player which was intended.

This matters most in minor chords. Cm(add2) puts a second a semitone from the minor third and sounds deliberately harsh; Cm(add9) spreads them an octave apart and sounds open. One note, two entirely different chords.

The guitar shapes that made them popular

Cadd9 is x32033: the C shape with two fingers moved to the third fret. Gadd9 (3x0203), Eadd9 (022102) and Aadd9 (x02420) all ring on open strings, and that ringing is the signature sound of acoustic songwriting.

None of these is harder than the chord it comes from. That is a large part of why they spread — players found them by leaving a finger down, not by studying harmony.

Sixth chords are the older half

Before maj7 became the standard resting chord, C6 was the way to end a piece: full but final, since no major seventh is pulling towards the root. Big-band arrangements close on sixths constantly.

Watch the terminology, though. In classical theory a "sixth chord" means the first inversion of a triad — three notes, not four. The two meanings collide in translation, and the catalogue keeps them apart on the pages themselves.

What to use them for

Anywhere the harmony must stay put without sounding empty: intros, pads, the last chord of a section, a long bar under a melody. There is no tritone, so nothing forces the music forward.

They are also the cheapest way to make a repeated triad stop sounding repetitive. Alternating C and Cadd9 across a bar changes the texture while the harmony does not move at all.

Frequently asked questions