The standard grips this chord is usually shown with.
Fmadd9 is F, Ab, C and G, a minor add nine. The shape this page opens on is written 133113, lowest string first.
Note by note. F is the root, Ab is the minor third, C is the fifth and G is the ninth.

Also written Fm(add9), Fmin(add9) or F-add9. The same chord either way; which spelling you meet depends on who wrote the chart.
There are 11 common shapes for Fmadd9 on the guitar, and 23 derived voicings in 2 families.
One note away. Change a single note of Fmadd9 and you have Fm (with one note taken away), Fsus2 (with one note taken away), Fsus2sus4 (with one note moved), Fm6 (with one note moved), Fm69 (with one note added) or Fm7 (with one note moved).
In which keys. Every note of Fmadd9 belongs to C minor (the iv), Eb major (the ii), F minor (the i) and Ab major (the vi).
The common shapes, written lowest string first: 133113, xx3113, xx6563, x86068, x8658x, x86x88, x-8-10-0-9-8, x-11-10-10-8-x, 13-11-x-12-13-x, 13-15-15-13-13-15, x-x-15-13-13-15.
Under the hand. None of the shapes for Fmadd9 uses an open string, so every one of them is movable; the lowest sits at the 1st fret. 3 of the 11 need a barre. Together they cover the neck from the 1st fret to the 15th.
Drop 2. A close-position chord with the second voice from the top lowered an octave. Sits on four adjacent strings. Fmadd9 has xx3113, 3331xx, xx5564, x-10-10-10-9-x, x-x-15-13-13-15, 15-15-15-13-x-x, 4855xx, x8658x.
Drop 3. The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped. Fmadd9 has 3x311x, x8x584, 4x556x, 8-x-6-10-8-x, x-10-x-10-9-8, 13-x-10-12-9-x, x-11-x-12-13-13, 15-x-15-13-13-x.
What kind of chord this is. Fmadd9 is a minor chord — root, minor third, fifth. minor chords on every root, and what they are for.
The common 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.