There has two install style: Inside mount and Outside mount
An inside mount simply means that the window covering fits neatly inside the window, outlining crisply the inside of the window frame and snugly fitting all around the inside. An inside mount offers the cleanest and most minimal look and can be installed as deep or as shallow as you desire.
For inside mount custom blinds, you can just enter your exact window size.
And we will help you take a 1/4" deduction off the width for better installation.
An outside mount is when blinds or shades are installed on the wall above the window or directly on the window trim. Blinds or shades are made larger than the window opening for complete coverage.
For outside mount custom blinds, we recommend adding at least 4 inches to the original size of the window.