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How to Measure for Arched Windows

Tips Before You Get Started

  • Use a steel tape measure for the most accurate measurements
  • If you’re considering an Inside Mount, make sure your window has enough depth to accommodate it
  • Always measure width (left to right) first and height (top to bottom) second
  • Record all measurements to the closest 1/8”, making sure to clearly identify which is your height and which is your width—it is very common to get them mixed up

Determine Inside Mount or Outside Mount

  • Inside mount shades will hang entirely within the window frame
    • We recommend inside mount whenever possible
    • Neat, streamlined look
    • Usually best for energy efficiency
  • Outside mount vertical cellular shades will hang outside your window opening, overlapping the edges
    • We recommend outside mount for windows with minimal mounting depth or obstructions within the frame
    • Minimizes light gaps, giving you better light control and privacy

Measuring for Inside Mount

Note: Inside mount shades will have a small deduction automatically applied by the manufacturer, to ensure proper fit

  1. Measure the width at the base of the arch, on the inside of the arch opening
  2. Record this measurement as your width
  3. Measure the height at the middle of the arch (the “tallest” point of the arch), on the inside of the arch opening
  4. Record this measurement as your height

IMPORTANT: If you wish to order an arch window treatment online, the height of the arch must be half its width, so that your arch is perfectly semicircular. If your arch is not a perfect semicircle, please call us at 800-575-8016 to discuss your options with one of our Design Consultants.


Measuring for Outside Mount

  1. Measure the width at the base of the arch, on the inside of the arch opening
  2. Record this measurement as your width
  3. Measure the height at the middle of the arch (the “tallest” point of the arch), on the inside of the arch opening
  4. Record this measurement as your height
  5. Simply add to your measurements to achieve the size desired
    • For composite wood arches, the factory will automatically add 1 ¼” to each side of the arch opening

IMPORTANT: If you wish to order an arch window treatment online, the height of the arch must be half its width, so that your arch is perfectly semicircular. If your arch is not a perfect semicircle, please call us at 800-575-8016 to discuss your options with one of our Design Consultants.