F#add9 is F#, A#, C# and G# — F# with the ninth added, and no seventh.
It sounds bright and ringing. No seventh at all: that is what “add” means, and it is why this sounds open where a maj9 sounds lush.

| F# | A# | C# | G# |
|---|---|---|---|
| 1 | 3 | 5 | 9 |
Tonic — a triad with one colour on it.
Also written F#(add9), F#add2 or F# add nine. The same chord either way; which spelling you meet depends on who wrote the chart.
Take the four notes stacked as close together as they go, then drop the second voice from the top an octave. The gap it opens is what makes the chord sound like a chord rather than a cluster.
It lands on four adjacent strings, which is why it is the workhorse voicing on guitar.
F#add9 has 12 of them, on the top four strings, the bottom four strings and the middle four strings, from open position up to the 11th — every inversion the chord has: F# in the bass, A# in the bass, C# in the bass and G# in the bass. The one to learn first is the F# shape at the 2nd fret, which is the easiest grip here.
4 of them sit on the top four strings, so you can run the inversions up one set without changing strings — which is the whole reason to learn them as a family rather than as separate grips.
Start with xx43x4 — no barre and only 3 fretted notes. None of the shapes for F#add9 uses an open string, so every one of them is movable; the lowest sits at the 1st fret. 2 of the 5 need a barre. Together they cover the neck from the 1st fret to the 14th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| 21x122 | 1st fret | F#, root position | F# | barred |
| xx43x4 | 3rd fret | F#, root position | G# | all fretted |
| x98696 | 6th fret | F#, root position | A# | all fretted |
| x98x99 | 8th fret | F#, root position | C# | barred |
| 14-13-x-13-14-x | 13th fret | F#, root position | C# | all fretted |
The same notes rebuilt from scratch give 9 drop 3 voicings, each on its own page.
How you get to it. The turn that lands on F#add9 is G#m7 to C#7 — the ii and the V of F# — and C#7 shares its third and seventh with G#m7, so the hand barely moves between them.
In which keys. Every note of F#add9 belongs to C# major (the IV), Eb minor (the ♭III), F# major (the I), Ab minor (the ♭VII), Bb minor (the ♭VI) and B major (the V).
Every note of F#add9 is in F# major pentatonic, F# major, F# lydian, F# mixolydian and F# lydian dominant.
Change one note of F#add9 and you have F# (drop the ninth), F#sus2 (drop the major third), F#sus2sus4 (the major third becomes a fourth), F#maj7 (the ninth becomes a major seventh), F#maj9 (add the major seventh) or F#madd9 (the major third becomes a minor third).
F#add9 is a major chord — root, major third, fifth. Major chords on every root.
On F#add9’s sound and use this page follows Robert Rawlins & Nor Eddine Bahha, Jazzology (Hal Leonard, 2005). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.