How wide and high should a curtain rod be? Move the rod and see

A curtain rod hung right on the window frame makes the window look smaller and leaves curtains sitting over the glass even when they are open. Hung a little higher and wider, the same window looks taller and lets in more light.

Set your window width and ceiling height, then move the rod and watch the open curtains. You get the rod length to buy, how much glass stays covered, and the gap left to the ceiling. Measure before you buy.