Depending on the style of the window, measuring for the draperies planned for that window will be different. When replacing existing draperies with a similar style, it is easy to measure the existing panels and duplicate those measurements for each window treatment.
For styles that will be contained within the frame of the window, measurements will all be taken inside the window frame. For these window treatments, measurements should be taken inside the frame, across the width of the window at the top, middle and bottom of the window. Measurements for the length should also be taken at the left and right sides of the frame, and in the middle if the window is especially wide. No window frame is exactly true and draperies that will hang inside the window frame should be no longer than the shortest measurement.
For draperies that will hang outside the window frame, measurements will be taken according to the size of the window, the desired length of the curtain, and the width of the rod upon which the curtains will hang. If draperies are to just brush the floor, but not “puddle” at the sides of the window, then the method of measuring at both sides and in the middle of the opening, all the way to the floor, should be employed. When measuring width for a curtain rod that does not wrap to the wall, then the width of the rod is all that is necessary, but if the intended curtain rod bends and touches the wall, then the two wrapping edges must also be included in all measurements for the width of those draperies. Draperies that will hang outside the window frame can often be purchased in standard sizes, such as 63”, 84” and 102” lengths.
Typically, the longer the length, the more formal the draperies will appear. Shorter lengths give a more informal or casual appearance.