What are the differences between rough-opening, frame-fit, and exterior flange dimensions?

  • Rough opening dimensions are dimensions of a hole cut by the manufacturer or by you for a window. 
  • Frame fit dimensions are the measurements pertaining to the portion of the window that fits into the rough opening.
  • Exterior flange dimensions account for the outermost part of the window’s frame on the outside and inside of the vehicle. In most cases, these measurements exceed the hole opening about 5/8″ per side. This measurement is critical to ensure there is proper clearance for the size of a window to be installed.