Curtain Calculator
How many panels, how wide a rod, and how high to hang it.
Outside edge of the casing, side to side
Most ready-made panels are 50″
Hanging height (optional)
How many panels, how wide a rod, and how high to hang it.
Outside edge of the casing, side to side
Most ready-made panels are 50″
Hanging height (optional)
Curtains make a window look bigger or smaller depending almost entirely on where you put the rod. This works out the rod width, the height, and how many panels you need to look full rather than skimpy.
The rod should extend 4 to 8 inches past the window frame on each side, so that the open curtains stack beside the glass rather than covering it. It hangs high — typically 4 to 6 inches above the frame, or close to the ceiling for a taller look. Panel count comes from fullness: the combined width of the panels should be about twice the width of the rod for a proper gathered look.
Example
A 36-inch-wide window with the rod extended 6 inches each side gives a 48-inch rod. For 2× fullness you need about 96 inches of curtain — two standard 50-inch panels.
4 to 6 inches above the window frame at a minimum, and closer to the ceiling if you want the room to feel taller. Hanging the rod right on the frame is the most common mistake.
The window width plus 8 to 16 inches, so the rod extends 4 to 8 inches past each side. That lets the open panels sit beside the window rather than blocking the light.
Enough that the panels together are about twice the rod width. For most windows that means two panels; for wide windows, four.