Root, third and seventh: the guide tones fix the quality, so the fifth is dropped. That is what leaves a string free, so pick a tension to put on top.
F7#9 is F, A, C, Eb and G# — F9 with the ninth raised a semitone.
It sounds gritty and contradictory. The minor third sounding over the major third; every guitarist knows it as the Hendrix chord.

| F | A | C | Eb | G# |
|---|---|---|---|---|
| 1 | 3 | 5 | ♭7 | ♯9 |
Altered dominant — dominant function with a blues third on top.
Also written F7(#9), F7+9 or F7♯9. The same chord either way; which spelling you meet depends on who wrote the chart.
Root, third and seventh. The third and seventh, the guide tones, are what make the chord major, minor or dominant, so the fifth can go: it says nothing the symbol needs.
Three notes means a spare string, which is the real point. Put a tension on it.
F7#9 has 4 of them, on the bottom four strings, the top four strings and the middle four strings, from open position up to the 12th — all in one inversion, so the bass note never moves. The one to learn first is the F shape at the nut, which is the easiest grip here.
Start with xx3244 — no barre and down at the nut. None of the shapes for F7#9 uses an open string, so every one of them is movable; the lowest sits at the 1st fret. 4 of the 8 need a barre. Together they cover the neck from the 1st fret to the 13th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| 131214 | 1st fret | F, root position | G# | barred |
| 131244 | 1st fret | F, root position | G# | all fretted |
| xx3244 | 2nd fret | F, root position | G# | all fretted |
| x33244 | 2nd fret | C, 2nd inversion | G# | all fretted |
| x8789x | 7th fret | F, root position | G# | all fretted |
| x-11-10-10-10-11 | 10th fret | G#, 9th in the bass | Eb | barred |
| 13-12-13-13-x-x | 12th fret | F, root position | G# | barred |
| x-12-13-13-13-13 | 12th fret | A, 1st inversion | F | barred |
The same notes rebuilt from scratch give 13 drop 2, 8 drop 3 and 13 rootless voicings, each on its own page.
Tensions. A shell of F7#9, root, third and seventh, leaves a string free, and the tones that belong over it are the #11 (B), the b13 (Db) and the 13 (D).
F7#9 is a dominant with its tension raised, so it still points at Bb — harder than a plain seventh does, because the altered tones sit a semitone from where they are going.
Voice by voice, F7#9 → Bb. 2 voices move by a semitone, and one note is common to both chords.
| In F7#9 | Moves | In Bb |
|---|---|---|
| F, the root | stays where it is | F, the fifth |
| A, the major third | rises a semitone | Bb, the root |
| C, the fifth | falls a whole tone | Bb, the root |
| Eb, the flat seventh | falls a semitone | D, the major third |
| G#, the sharp ninth | rises a whole tone | Bb, the root |
Every note of F7#9 is in F half-whole diminished.
Change one note of F7#9 and you have Fm7 (drop the major third), Fm9 (the major third becomes a ninth), F7 (drop the minor third), F9 (the minor third becomes a ninth), F7b9 (the minor third becomes a flat ninth) or F/D# (drop the minor third).
F7#9 is an altered chord — a dominant seventh with its fifth or ninth moved. Altered dominant chords on every root.
On F7#9’s sound and use this page follows Mark Levine, The Jazz Theory Book (Sher Music, 1995). 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.