Add a minimum of 15cm either side, preferably more, but for full curtains, single curtains or wide windows allow at least 30cm if you have the room, excluding the length of the finials (decorative pole ends). Ideally you want your curtains to fit either side of the window when drawn so as not to block out any light.
Choose a stock pole length. If you want it cut to a bespoke length, fill out the "cut pole to size" notes box, and we will do this at no extra charge.
Helpful tip: Ensure there is room for your finials beyond the ends of your pole.