Add9 chords, and how they differ from 9 chords

Add9 chords are the reason so much acoustic guitar sounds wide and ringing rather than plain. You keep the major chord exactly as it is and add one note, the ninth, and the chord opens up like a window. Cadd9 is probably the most played of them all. The other thing to sort out on this page is a naming trap: add9 and 9 look almost identical on a chart and are two very different chords.

What an add9 chord is

An add9 chord is a major triad with the ninth added on top. The formula is 1, 3, 5, 9. The ninth is the same note as the second, a whole step above the root, placed an octave higher.

The important part is what stays: the major third. It is what keeps an add9 chord a major chord. Take the third away and put the ninth in its place, and you have a different family, the sus2 chords.

Add9 versus 9: one note, a different job

The word "add" is not decoration. In chord names, a plain number above 7 implies every odd-numbered note below it. So a 9 chord contains the seventh as well: it is a dominant seventh chord with the ninth on top. An add9 chord says "add the ninth, and only the ninth": no seventh.

In practice: if you see Cadd9 in a pop or folk song, the chord is a resting major chord. If you see C9 or E9, especially in funk, blues or soul, it is a dominant chord built on the seventh chord and you need that flat seventh. Playing one for the other changes the harmony, not just the color.

The add9 shapes to learn

The most useful add9 chords are open shapes, because the open strings supply the ninth for free. Cadd9 keeps the C major bass and moves two fingers to the top. Gadd9 puts the ninth on the third string. Eadd9 and Aadd9 are E and A major with one finger moved.

Two more are worth knowing even though they ask more of the hand. Dadd9 is x x 0 2 5 2: the open D with E on the second string, reached with the fourth finger at the fifth fret. Badd9 is x 2 4 6 4 2, a barred B with the fourth finger stretched to the sixth fret, which spans five frets and takes some practice. Fadd9, 1 x 3 2 1 3, keeps the F in the bass with the thumb or the first finger.

The 9 chords

Ninth chords are a different animal: dominant chords, with the tension of a seventh chord and the extra color of the ninth on top. E9 in open position and the movable shape with the root on the fifth string are the two to start with.

The D9 shape is movable: slide it down two frets for C9, up two for E9, and so on. In funk rhythm guitar it is often played on the top four strings only, with short, muted strums; in a blues it can replace any of the three dominant chords. The D9 and E9 pages go further.

How to use add9 chords

An add9 chord can stand in for a major chord almost anywhere, which is both its strength and its danger. Try it first on one chord in a progression, the one that lasts longest:

To hear Cadd9 in a real song, listen to Wonderwall by Oasis: it comes in with the chorus section, after the verse loop. The song is played with a capo at the second fret, so the shape you finger as Cadd9 actually sounds as Dadd9. The transposing with a capo guide explains why.

The limit is the melody. The ninth is a whole step above the root, and if the singer is holding the root at the same time, the two notes can rub. Play the add9 against the actual tune and keep it only where it helps. If every chord in the song becomes an add9, nothing sounds special any more.