Where to capo for F# major
Put the capo at fret 6 and play F# major using B# major shapes. That is the easiest of the eight positions ranked below, and it is what most players reach for. Against playing F# major open, it drops the mean difficulty of the key's seven chords from 5.6 to 3.4 and gains 16 ringing open strings.
You want F#. Capo 6 and play in B#.
All eight positions, ranked
Each row transposes F# major down by that many frets to find the shapes your hand would actually make, then scores the best voicing of all seven chords — fewer fingers, less stretch, closer to the nut, fewer muted strings. Lower is easier. Standard tuning (E2 A2 D3 G3 B3 E4).
What you are playing
The seven chords of F# major are F#, G#m, A#m, B, C#, D#m, E#dim — the ones the ranking above is scored against. Their diagrams are on the F# major key page.