Here is an easy guide to help you measure for Levolor Cirrus & Designer Textures Shades.

Inside Mount Installation To find width: Measure exact distance between inside surfaces of window frame at the top, middle and bottom, and use the narrowest width. Do not make any width deductions. To find length: Measure exact distance from inside surface at top of window to sill. If you prefer blind not to touch sill, deduct 1/4". If there is no sill, measure length to point where shade is to reach.

Outside Mount Installation To find width: Measure exact distance between the outermost points where the shade is to be placed. This measurement should overlap each side of the window by at least 1-1/2". Factory makes no deduction from your fabric width dimensions.. To find length: Measure exact distance from where top of shade will be located to top of sill. If there is no sill or if shade is to overlap window frame, measure to point blind is to reach.