The short answer
A common guide is to fix the pole or track 10–15 cm above the window frame, and to extend it 15–30 cm past each side. Go higher, up to just below the ceiling or cornice, if you want the window to look taller. Then measure the drop from the point the curtain hangs from to where it should finish.
Try the Curtain Drop CalculatorThe standard position
Fixing the pole or track 10–15 cm above the top of the window frame is a widely used guide. It leaves room for the heading and the rings, and keeps the top of the curtain from showing the frame or the wall above it.
Extend the hardware 15–30 cm past each side of the frame where the wall allows it. That lets the curtain stack back beyond the glass when open, so it does not cover the light.
Going higher
Hanging the pole or track nearer the ceiling, or on the ceiling itself, draws the eye up and makes the window and the room feel taller. This works best when the curtain is floor-length, so the line from top to bottom is unbroken.
The limits are the ceiling, any cornice or coving, and a minimum gap above the pole for fixings. Leave enough space to fit brackets and, for a pole, to slide the rings over the end.
Where the curtain should finish
A floor-length curtain commonly finishes about 1 cm above the floor. A sill-length curtain finishes just above the sill, and a below-sill curtain finishes 10–15 cm below it, so it covers the edge of the sill and any apron.
The drop is measured from the point the curtain hangs from, such as the ring eye or glider, not the top of the pole. The curtain drop calculator works this out for you from the height of the hanging point and the finish you choose.
Check before you drill
Use a detector to check for pipes and cables behind the wall before you drill, and find out whether there is a lintel or solid fixing point above the window. Fix brackets into masonry or studs with the right plugs, and add a centre bracket for a long pole (commonly beyond about 1.2–1.5 m, so check the maker's instructions).
Mark the positions with a pencil and a spirit level, and check them from across the room before you drill. A second look from a distance often shows a bracket that is slightly out of line.
Worked example
Suppose the top of the window frame is 200 cm above the floor. Fixing the pole 10–15 cm above gives a pole height of 210–215 cm. If the curtain rings hang so that the hanging point is at 215 cm and the curtain should finish 1 cm above the floor, the finished drop is 214 cm.
If the curtains were below-sill instead, with the sill at 100 cm and a finish 15 cm below it, the curtain would end 85 cm above the floor, and the drop would be 215 − 85 = 130 cm.
This guide is general information to help you plan, not professional advice. Check product instructions and your supplier's guidance before you buy, and ask a qualified professional about structural or safety-related work. See our terms of use.