Blinds.com knows that the perfect fit for a beautiful new window treatment all starts with an accurate measurement. If you’re planning a DIY window treatment project, our How to Measure angle-top and angle-bottom windows guide makes measuring easy!

You can also call our Customer Experience Center for an immediate quote once you have your measurements. Don’t forget you can always Find a Pro in your area to complete the project for you!

What You Will Need

Helpful Hints Before You Begin Measuring Angle-Top or Angle-Bottom Windows:

  • For the most accurate measurements, only use a steel tape measure.
  • Don’t mix up width and height measurements. Always follow the width by height format (W x H) and mark them as such.
  • Measure to the nearest 1/8 inch. Never round up or down to the nearest half or whole inch.
  • If you’re measuring for more than one window, measure each one individually – never assume that your windows are the same size, even if they may look alike.

How to Measure Inside Mount Angle-Top or Angle-Bottom Windows

Inside mount shades hang within the window opening. This is the mount we recommend in most cases, as it provides a neat, clean look and usually easier installation.

Note: For inside mount, use exact measurements, without making any deductions. The factory will apply deductions when making your product to ensure a proper fit.

  1. Measure width from left to right at the top, middle and bottom of the rectangular portion of your window opening. Always measure at the depth within the window frame where you’ll install your brackets. You will not take any measurements from the angled portion for this step.
  2. Record the smallest of the three measurements to the nearest ⅛”.
  3. Measure the height of the “tall side” of the window opening, from the bottom edge to the top corner of the angled portion (for an angle-top window), or from the top edge to the bottom corner of the angled portion (for an angle-bottom window).
  4. Record this measurement (to the closest ⅛”) as your height.
  5. Measure the height of the “short side” of the window opening, from the bottom edge (for angle-top windows), or from the top edge (for angle-bottom windows), to where the angle starts.
  6. Record this measurement (to the closest ⅛”) as your “short side height”.
  7. Measure the length of the angled line, from where the angled portion of the window starts to its top corner (angle-top windows) or its bottom corner (angle-bottom windows).
  8. Record this measurement (to the closest ⅛”) as your “angle length”.

How to Measure Outside Mount Angle-Top or Angle-Bottom Windows

Outside mount shades hang outside your window opening, overlapping the edges. We recommend outside mount for windows that have inadequate mounting depth or obstructions that prevent a shade from being mounted, as well as for windows that are out of square.

To determine if your window is out of square, take both diagonal measurements, from corner to corner, only in the section of the window that isn’t angled. If the difference between the two is ⅛” or more, the window is out of square.

Note: Record your exact measurements, without making any deductions. The factory will make your shade to the exact dimensions you provide.

  1. Measure the window opening from left to right, in only the non-angled section of the window, and add the amount you want the shade to overlap the window opening. We recommend at least 2” on both sides.
  2. Record this measurement as your width.
  3. Determine where you want the top corner (for angle-top windows) or the bottom corner (for angle-bottom windows) of the “tall side” of your shade to be, and mark the spot.
  4. Measure the height from the spot you marked to the bottom of the window opening (for angle-top windows) or to the top of the window opening (for angle-bottom windows). Add the amount you want your shade to overlap. We recommend at least 2”.
  5. Record this measurement as your height.
  6. Determine where you want the “short side” of your shade to end and mark the spot.
  7. Measure the height from the spot you marked to the bottom of the window opening (for angle-top windows) or to the top of the window opening (for angle-bottom windows). Add the amount you want your shade to overlap. We recommend at least 2”.
  8. Record this measurement as your “short side height”.
  9. Measure the length of the angled line, connecting the spot you marked for the short side to the spot your marked for the tall side.
  10. Record this measurement as your “angle length”.

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