📌 Key Takeaway: Inside-mount and outside-mount blinds require different measurement approaches — getting this wrong is one of the most common reasons custom blinds don't fit properly on arrival.

Inside Mount vs. Outside Mount

  • Inside mount — blinds fit within the window frame itself, requiring at least 1.5-2 inches of depth for proper mounting hardware clearance.
  • Outside mount — blinds mount on the wall or trim surrounding the window, covering the full frame — a good option when frame depth is insufficient for inside mount, or when you want to make a window appear larger.

Basic Measuring Steps

  • Measure width at the top, middle, and bottom of the window opening — use the narrowest measurement for inside mount to ensure clearance.
  • Measure height at the left, center, and right sides — use the longest measurement for inside mount.
  • Measure frame depth to confirm inside-mount feasibility before ordering.
  • For outside mount, decide how far beyond the frame you want the blinds to extend on each side (typically 2-3 inches) and add that to your frame measurements.

Why Professional Measuring Is Often Free

Many retailers offer free professional measuring even if you plan to self-install the blinds afterward — worth taking advantage of specifically to avoid an expensive custom-order mistake, since custom blinds typically aren't returnable once cut to size.

Tools You'll Need

A steel tape measure (not cloth, which can stretch and introduce error) is essential for accurate results — measure to the nearest eighth of an inch for custom orders, since small errors compound when applied to multiple windows across a whole-home project.

Frequently Asked Questions

What happens if I measure incorrectly for custom blinds?

Custom-cut blinds typically can't be returned or exchanged once manufactured to your specific measurements — this is exactly why free professional measuring services are worth using, even for a DIY installation.

Do I need different measurements for each window, even if they look the same size?

Yes — even windows that appear identical often have slight variations due to home settling or construction tolerances. Measure each window individually rather than assuming they're all the same.