The width of your curtains should be the same width as your curtain track or pole, excluding the finials. Ideally the pole or track should be 6″- 12″ wider than the window and positioned 6″ above it.
Measure from the top of your curtain track or pole, to where you want the curtain to drop. We recommend that sill-length curtains stop 6″ below the window sill to prevent drafts and floor-length curtains stop 1/2″ above the floor to avoid wear to the hems.