How to measure for window treatments
There are entire books and websites dedicated to window treatments, and when it comes to blinds, shutters and valances, often a professional is the best way to go. If you are dressing up a room with curtains, that is something you may be able to do on your own, as long as you have a measuring tape. This is a basic how-to so you can get the height and width correct.
Hang your curtain rail 4-5 inches above the top edge of your window fame.
If you have higher ceilings, you can hang your rod even higher.
Leave 8-10 inches on either side of the window trim.
This will allow more natural light to come through the window when the curtains are completely open.
Measure from the curtain rod down to about 1 inch above the floor.
Curtain Rings: Measure from the top of the clip.
Measure the width of your window from the edge of the trim. Add 6-10 inches on either side.
Volume: Multiply your width by 1-2 inches to achieve fullness.
Hanging sheer curtains: Triple the width of your measurement for full-looking sheer curtains.