To create the illusion of a taller window, mount the rod four to six inches above the window frame-or halfway between the frame and the ceiling molding. (But within reason-don’t go more than eight inches above the frame or it might look awkward.) A track mounted on the ceiling also lengthens windows. Be sure to account for the extra fabric when measuring.
Extending the rod three to six inches beyond the frame on each side makes a window feel grander and allows extra light to stream in when the curtains are open (the fabric hangs against the wall without blocking the glass). You can also use this plan to reveal pretty molding. In this case, you may want to leave as much as 12 inches on either side. Remember to adjust your width measurements for this look.