Provide exact inside mount window dimensions. Blind will fit within the window frame opening. The factory will take automatic deductions on ordered width.
Vertical blinds have a deduction automatically taken by the factory on both the width and height.
Mounted outside window opening on window frame or drywall.
The factory will not take deductions. It is recommended to add a minimum of 2" to 3" per side of the window opening for proper overlap and optimal light control.