The standard grips this chord is usually shown with.
F#5 is F# and C#, a power chord. The shape this page opens on is written 244xxx, lowest string first.
Note by note. F# is the root and C# is the fifth.

Also written F#(no 3rd) or F# power chord. The same chord either way; which spelling you meet depends on who wrote the chart.
There are 2 common shapes for F#5 on the guitar, and 21 derived voicings in the triad family.
One note away. Change a single note of F#5 and you have F# (with one note added), F#m (with one note added), F#sus2 (with one note added) or F#sus4 (with one note added).
In which keys. Every note of F#5 belongs to C# major (the IV), C# minor (the iv), D major (the iii), Eb minor (the ♭III), E major (the ii), F# major (the I), F# minor (the i), Ab minor (the ♭VII), A major (the vi), Bb minor (the ♭VI), B major (the V) and B minor (the v).
The common shapes, written lowest string first: 244xxx, x-9-11-x-x-x.
Under the hand. None of the shapes for F#5 uses an open string, so every one of them is movable; the lowest sits at the 2nd fret. None of them needs a barre. Together they cover the neck from the 2nd fret to the 11th.
Triad. Three notes across one string set. F#5 has 244xxx, x446xx, x-9-11-11-x-x, 9-9-11-x-x-x, 9-9-11-11-x-x, 2446xx, xx467x, x4467x.
What kind of chord this is. F#5 is a suspended chord — root and fifth, with a second or fourth where the third would be — or nothing at all. suspended and power 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.