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Window Measurement Cheat Sheet

Updated March 2026 1-page printable
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This cheat sheet is designed to print cleanly. Press Ctrl+P (Windows) or Cmd+P (Mac) to print or save as PDF. The header, footer, and navigation are hidden automatically.

Tools you need

  • Steel tape measure (not fabric — fabric stretches)
  • Pencil (to mark bracket positions)
  • Notepad or the measurement table below

Inside mount: 3 steps

The blind sits inside the window frame for a clean, built-in look.

1

Measure width

Measure the inside of the frame at the top, middle, and bottom. Record the narrowest measurement.

2

Measure height

Measure the inside of the frame on the left, center, and right. Record the longest measurement.

3

Measure depth

Measure from the front edge of the frame to the glass. You need at least 1.5" for most blinds.

Do not round up

Always round down to the nearest 1/8 inch for inside mount. A shade that is too wide will not fit inside the frame.

Outside mount: 3 steps

The blind mounts on the wall above and around the window frame. Use this when the frame is too shallow for inside mount, or when you want to block more light.

1

Measure width

Measure the outer width of the area you want to cover. Add 3" total (1.5" overlap on each side) to block light gaps.

2

Measure height

Measure from where the top bracket will sit to the window sill. Add 3" above the frame for bracket clearance and light blocking.

3

Mark positions

Use a pencil to mark bracket positions on the wall before drilling. Double-check that marks are level.

The 1.5-inch depth rule

If the depth from the front of your window frame to the glass is less than 1.5 inches, you cannot inside-mount most blinds. You must use outside mount instead.

Quick test

Stack two quarters — each is about 1/8". If you can fit a stack of 12 quarters (1.5") between the front edge of the frame and the glass, inside mount will work. If not, plan for outside mount. Full mounting guide →

5 common measurement mistakes

  1. Measuring only once. Always measure width and height in three places. Window frames are rarely perfectly square.
  2. Using a fabric tape measure. Fabric stretches over time. Use a rigid steel tape for accuracy.
  3. Rounding up for inside mount. Round down to the nearest 1/8". Too wide means the shade will not fit.
  4. Forgetting frame depth. If you skip the depth check, you may order inside-mount blinds that cannot physically fit inside your frame.
  5. Measuring the glass, not the frame. For inside mount, measure the frame opening (where the blind sits), not the glass pane itself.

Quick reference: what to order

Mount Type Width to Order Height to Order
Inside mount Narrowest of 3 measurements (round down to 1/8") Longest of 3 measurements (round down)
Outside mount Outer frame width + 3" total overlap Desired coverage + 3" above frame
No-drill / tension Exact inside frame width (shade expands to fit) Inside frame height

Your window measurements

Fill in before you shop. Bring this with you to the store or keep it open when ordering online.

Room Window # Width Height Depth Mount Type