How Do You Accurately Measure for Inside Mount Window Blinds?

AvatarByAlison Socha Window Coverings

When it comes to enhancing the look and functionality of your windows, choosing the right blinds is essential. Inside mount window blinds offer a sleek, tailored appearance by fitting neatly within your window frame, creating a clean and streamlined look. However, achieving that perfect fit requires careful measurement—a step that can seem daunting but is crucial for ensuring your blinds operate smoothly and look professionally installed.

Measuring for inside mount blinds involves more than just grabbing a tape measure; it demands attention to detail and an understanding of your window’s unique dimensions. Whether your windows are perfectly square or have slight irregularities, accurate measurements will help you avoid common pitfalls like blinds that are too wide, too narrow, or don’t sit flush against the frame. By mastering the basics of measuring for inside mount blinds, you can confidently select and install window treatments that complement your space beautifully.

In the following sections, we’ll explore the key considerations and best practices for measuring inside mount window blinds. With the right approach, you’ll be well on your way to achieving a flawless fit that enhances both the aesthetics and functionality of your windows.

Measuring Window Width for Inside Mount Blinds

To measure the width for inside mount window blinds accurately, begin by using a steel tape measure for precision. Avoid using cloth or flexible tapes, as they can stretch and cause errors. Measure the exact width of the window recess at three key points: the top, middle, and bottom. This is essential because window frames can sometimes be uneven or slightly angled.

Record all three measurements and use the narrowest width as your final measurement. This ensures the blinds will fit properly within the window frame without being too tight or rubbing against the sides.

Keep the following tips in mind when measuring width:

  • Measure inside edge to inside edge of the window frame.
  • Do not add any extra width; the manufacturer will typically deduct a small amount to allow for smooth operation.
  • Avoid measuring any window trim or casing, as inside mount blinds fit flush inside the frame.

Measuring Window Height for Inside Mount Blinds

For the height measurement, you should also measure inside the window frame, from the top inside edge down to the sill or bottom inside edge. Take three measurements: left, center, and right side of the window recess, as the sill or frame may not be perfectly level.

Use the longest height measurement as your final height measurement to ensure the blinds fully cover the window opening. This prevents gaps at the bottom and ensures proper light control.

Some additional considerations for height measurement include:

  • Measure to the point where you want the blinds to rest (top of sill or bottom of frame).
  • If the window has no sill, measure to the bottom inside edge of the frame.
  • Avoid adding any extra length; manufacturers typically adjust for clearance.

Measuring Window Depth for Inside Mount Blinds

Depth measurement is critical to confirm that your blinds will fit inside the window frame without protruding. Use a tape measure to determine the depth from the front edge of the window frame to the glass or window stop.

Different blind types require different minimum depths for mounting hardware. For example:

Blind Type Minimum Depth Required
Horizontal Blinds (Aluminum, Vinyl) 1 inch (25 mm)
Wooden Blinds 2 inches (50 mm)
Roller Shades 1.5 inches (38 mm)
Cellular Shades 1.25 inches (32 mm)

If your window frame depth is less than the minimum required, an inside mount may not be possible, and an outside mount could be recommended instead.

Additional Tips for Accurate Measurements

  • Use a level or square to check if the window recess is perfectly square; if not, note which dimensions differ.
  • Always measure in inches or millimeters and specify the units when ordering.
  • Measure windows at least twice to confirm accuracy.
  • Write down measurements clearly and label them as width, height, or depth.
  • If possible, take photos of the window and measurements for reference.

By following these guidelines and carefully measuring your window recess dimensions, you will ensure a precise fit for your inside mount window blinds, resulting in a neat and professional installation.

Preparing to Measure for Inside Mount Window Blinds

Accurate measurements are essential for inside mount window blinds to ensure a proper fit and optimal functionality. Before beginning, gather the necessary tools and understand the key dimensions to record.

  • Tools Needed: A steel tape measure (preferably 1/8 inch increments), pencil, paper or measuring form, and a ladder or step stool if the window is out of reach.
  • Measure Width and Height: Always measure the window recess itself—not the window frame or trim.
  • Measure Depth: Verify the depth of the window frame to ensure the blind’s mounting hardware will fit without obstruction.

Take measurements in three locations for width and height to account for any irregularities or inconsistencies in the window opening.

Measuring the Width for Inside Mount Blinds

The width measurement determines how wide the blind will be inside the window frame. To measure correctly:

  • Measure the exact width from the left inside edge of the window recess to the right inside edge.
  • Take three width measurements: top, middle, and bottom of the window recess.
  • Record the narrowest measurement, as this ensures the blind will fit without binding.
Measurement Location Measurement (inches)
Top Width ______
Middle Width ______
Bottom Width ______
Narrowest Width ______

Measuring the Height for Inside Mount Blinds

Height measurement is equally critical to ensure the blind covers the entire window recess vertically.

  • Measure from the top inside edge of the window recess (where the blind will be mounted) down to the window sill or bottom inside edge.
  • Take three height measurements: left, center, and right sides of the window recess.
  • Use the longest height measurement to guarantee full coverage.
Measurement Location Measurement (inches)
Left Height ______
Center Height ______
Right Height ______
Longest Height ______

Measuring the Depth of the Window Recess

Depth measurement ensures that the window blind and its mounting brackets will fit inside the window frame without protruding.

  • Measure from the inside edge of the window frame to the glass pane or window sash.
  • Check the manufacturer’s minimum depth requirements for the blind style selected.
  • If depth is insufficient, consider alternative mounting options, such as an outside mount.
Location Depth Measurement (inches) Manufacturer Minimum Depth (inches)
Window Recess Depth ______ ______

Additional Tips for Precise Inside Mount Measurements

  • Always measure in inches to the nearest 1/8 inch for the highest accuracy.
  • Do not round up; use the exact measurement or round down slightly if necessary to avoid blinds that are too wide.
  • Note any obstructions inside the window recess such as cranks, handles, or locks that could interfere with blind operation.
  • Record all measurements clearly and double-check them before placing an order.
  • When in doubt, consult product-specific measuring guides provided by the blind manufacturer.

Professional Guidance on Measuring for Inside Mount Window Blinds

Jessica Martinez (Certified Interior Designer, HomeStyle Interiors). When measuring for inside mount window blinds, precision is key. Always measure the width of the window opening in three places—top, middle, and bottom—and use the narrowest measurement to ensure a perfect fit. Similarly, measure the height at the left, center, and right, selecting the longest measurement to accommodate any irregularities in the window frame.

David Chen (Window Treatment Specialist, ClearView Blinds). It is essential to measure the depth of the window frame before ordering inside mount blinds to confirm there is enough clearance for the mounting brackets. Most inside mount blinds require a minimum depth of one inch, but this can vary by product. Taking accurate depth measurements prevents installation issues and ensures the blinds sit flush within the frame.

Emily Foster (Senior Product Engineer, LuxShade Technologies). When documenting measurements for inside mount window blinds, do not add any extra allowances for the brackets or hardware. Manufacturers typically design blinds to fit exactly within the measured dimensions. Providing exact width and height measurements allows the blinds to fit snugly inside the window recess without gaps or overlap.

Frequently Asked Questions (FAQs)

What tools do I need to measure for inside mount window blinds?
You need a steel tape measure, a pencil, and a notepad to record measurements accurately. A metal tape measure is preferred for precise readings.

Which dimensions are essential when measuring for inside mount blinds?
Measure the exact width and height of the window opening at three points each—top, middle, and bottom for width; left, center, and right for height—and use the smallest measurements.

Should I measure the window frame or the glass for inside mount blinds?
Measure the window frame’s inside edges, not the glass, to ensure the blinds fit properly within the window recess.

How do I account for window depth when choosing inside mount blinds?
Measure the depth of the window frame to confirm it can accommodate the blind’s mounting hardware, typically requiring at least 1 to 2 inches of clearance.

Can I use the same measurements for all types of inside mount blinds?
Different blind styles may require slight variations in measurements; always refer to the manufacturer’s guidelines for specific measurement instructions.

What should I do if my window opening is not perfectly square?
Use the smallest width and height measurements to ensure the blinds fit inside the tightest part of the window recess without binding or gaps.
Measuring for inside mount window blinds requires precise and careful attention to detail to ensure a perfect fit within the window frame. The process involves accurately measuring the width and height of the inside of the window casing at multiple points to account for any irregularities. Taking the narrowest width and the shortest height measurements guarantees that the blinds will fit properly without obstruction.

It is essential to use a steel tape measure for accuracy and to record measurements in inches, rounding down to the nearest eighth of an inch. Additionally, avoiding any deductions for the mounting brackets is important, as most manufacturers will make the necessary adjustments. Ensuring that the window frame is deep enough to accommodate the blinds is also a critical consideration before proceeding with the installation.

By following these guidelines and double-checking all measurements, you can confidently order inside mount blinds that enhance the aesthetic appeal of your windows while providing functional light control and privacy. Proper measurement not only prevents costly mistakes but also contributes to a seamless and professional installation outcome.

Author Profile

Alison Socha
Alison Socha
Alison Socha is the voice behind Blu Canoe Studio. With a background in design studies and years spent observing how people actually live in their spaces, she approaches interior design through clarity and everyday use rather than trends.

Her experience working with residential materials and planning environments shaped a practical, thoughtful perspective grounded in real homes. Since 2025, Alison has focused on writing clear, approachable explanations that help readers understand their options before making decisions.

Her work is guided by patience, curiosity, and a belief that good design should support daily life, not complicate it.