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How to Measure Arch Windows for Blinds & Shades, Step-by-Step

Large Arch Window

Source: Dariusz Jarzabek/

In the world of interior design, curtains and blinds are like the final brushstrokes on a masterpiece, adding depth and personality to your home. They frame the outside world, control the flow of light, and create an ambiance that's uniquely yours.

But when it comes to choosing between blinds vs shades, it's a bit like deciding between classic black and white or a burst of colour. Window shades offer versatility, while window blinds exude timeless charm. No matter your preference, achieving the perfect look is more attainable than ever. That includes arched windows, which add a touch of architectural elegance to any space.

With our guide, we'll walk you through the process of how to measure an arch window, as well as selecting the perfect window treatments for these unique architectural features. Whether it's embracing the simplicity of blinds or the soft elegance of shades, we've got you covered in creating a harmonious, stylish environment.

So let's embark on this journey to transform your arch windows into stunning focal points that reflect your personal style.


Determine What Types of Arches You Have

The first step to measuring for arch window shades is know what types of arches you have. There are five kinds of window arches you should know:

  • Perfect arch: A perfect arch has a height exactly half the length of the width. Basically, if you took a circle and chopped it in half, you would get a perfect arch; hence, the name.


  • Palladian arch: In a palladian arch, the height is greater than half the width, resulting in a dramatic appearance. A palladium arch is taller than a perfect arch. You will want to be especially sure your palladium arch treatment has a strong base mount since it is taller than the other options listed here.
  • Eyebrow arch: In an eyebrow arch, the height is smaller than half the width, creating a flatter curve. An eyebrow arch is shorter than a perfect arch.
  • Eyebrow arch with legs: This is a variation of the eyebrow arch, where straight “legs” extend beneath the arch—picture a rectangle topped with a curve. For this type of window arch, you will need to measure the legs as well as the arch itself.
  • Quarter arch: This style of arch is one-half of a regular arch and a quarter of a sphere or oval; hence, the name. A quarter arch is formed at a right angle with the arch across from it. A quarter arch may be perfect, or it may be elongated in either direction. It may also have legs that extend from the bottom.
second floor landing

Source: Artazum/

Tools Required

Measuring your arch windows accurately ensures that you achieve the perfect fit for your blinds or shades. To ensure precision and a hassle-free process, you'll need a few essential tools at your disposal.

Here's a list of what you'll require:

  • Steel Tape Measure: A reliable steel measure tape is your go-to tool for measuring the height, width, and various dimensions of your arch windows. Its flexibility and durability make it ideal for capturing precise measurements.
  • Pencil: A trusty pencil will allow you to mark the measurements directly on your window frame or the surface you're working on. These marks will serve as your reference points, ensuring accuracy in the installation process.
  • Notepad or Measuring Worksheet: Keeping track of your measurements is crucial. This will help you record and organize the measurements for each section of your arched window.
  • Ladder or Step Stool (if needed): Depending on the height of your windows, a ladder or a step stool may be necessary to safely reach and measure all areas of your arch window.
  • Level: A level is handy for ensuring that your measurements are accurate both vertically and horizontally. It ensures that your blinds or shades will hang straight and look visually appealing.
  • Plumb Bob: For arched windows with complex shapes, a plumb bob can help you determine the exact point where a cord will hang, ensuring a snug fit.

Accurate measurements are crucial for selecting the right blinds or shades and ensuring a seamless and stylish window treatment installation.

Inside vs. Outside Mount


When it comes to installing blinds or shades, one of the key decisions you'll need to make is whether to go with an inside mount or an outside mount. Each mounting option has its unique advantages, and understanding the differences between them can help you achieve the perfect look for your windows.

Let's delve into the details of inside and outside mounts.

Inside Mount

An inside mount means that your blinds or shades are installed inside the window frame. This creates a sleek and streamlined appearance, allowing your window frame to serve as a natural frame for your window treatment.

Inside mounts are preferred when you want to showcase the architectural beauty of your windows or maintain a clean, uncluttered look in your space.

Here is how to measure for an inside mount:

  1. Measure the width at the top, middle, and bottom of the inside of the window frame.
  2. Record the smallest width measurement to ensure a proper fit.
  3. Measure the window height at the left, center, and right of the inside of the window frame.
  4. Record the longest height measurement to ensure your blinds or shades cover the entire window.

Outside Mount

With an outside mount, your blinds or shades are mounted outside the window frame, typically above or beyond it. This approach provides excellent coverage, effectively blocking out light and offering additional privacy.

Outside mounts are an excellent choice when you want to make your windows appear larger or to conceal an unattractive window frame.

Here is how you measure for outside mounts:

  1. Measure the window height and width of the area you want your blinds or shades to cover. This can extend beyond the window frame.
  2. Ensure that your measurements include enough space for mounting brackets, as well as any desired overlap on each side.

Ultimately, the choice between inside and outside mounts depends on your design preferences and the specific needs of your space. Whether you're aiming for elegance and subtlety or maximum functionality and coverage, understanding these mounting options will help you make an informed decision that perfectly complements your interior.

How to Measure Arch Window Shades and Blinds

Getting the right measurements for your arch window shades and blinds is crucial to achieving a polished, well-tailored look. Precision is key when it comes to ensuring your window treatment not only functions correctly but also enhances the aesthetics of your space.


Inaccurate measurements can lead to ill-fitting shades or blinds, which can be a costly and time-consuming oversight to correct. To help you avoid such issues, here are step-by-step instructions for measuring your arch windows accurately:

  1. Measure the Bottom of the Arch: Using a steel tape measure, start by measuring the bottom of the arch at its widest point. Measure to the nearest 1/8 inch, and make sure you're measuring only the window opening, excluding any trim. Record this measurement.
  2. Measure the Height: Similarly, measure the height of the arch at its highest point, again to the nearest 1/8 inch. This time, note only the window opening's height, excluding any trim.
  3. Measure the Arch Legs (If Applicable): If your arch has legs, measure the height of each leg individually, also to the nearest 1/8 inch. It's not uncommon for uneven window measurements in older buildings, so measure each leg separately, as one may be longer than the other.

Measuring for Inside Mounts

If you're planning to install blinds inside the window frame, you can use the measurements you've just taken as is. Avoid making deductions yourself, as manufacturers will adjust the size to ensure a snug fit. Making deductions on your own may result in blinds that are too short.


Source: Roschetzky Photography/

Measuring for Outside Mounts

Meanwhile, blinds installed outside the window frame and overlapping the window trim will require you to make some additions to your measurements.

  1. Determine where you'll mount the arch window treatment at the bottom. If you're also planning to install blinds on the bottom window, ensure there's enough space to prevent hardware collision.
  2. Once you've established the mounting hardware's drop below the window, add that measurement to the height. Additionally, decide how much you want the shade to extend above the window arch. A minimum window measurement of three inches of overlap at the top for privacy is recommended.
  3. Apply the same principle to the sides of the window, aiming for at least two inches of overlap on each side for a total of four extra inches. Remember that deductions are not taken for outside mount window treatments, so the measurements you provide will be the final measurements.
  4. Double-check their accuracy before placing your order to ensure a perfect fit.

Accurate measurements are the foundation of a successful installation, whether you're opting for inside or outside mount arch window shades and blinds. Following these steps diligently, you can achieve a flawless, functional window treatment tailored to your space.

Common Mistakes to Avoid

Avoiding common mistakes during the measurement process can save you time, money, and frustration in the long run. Let's take a look at some frequent errors and how to steer clear of them:

  • Neglecting to Measure Twice: Measuring once might be a saying, but it's not a rule to follow here. Always measure twice to ensure accuracy. This helps catch any discrepancies and inconsistencies in your measurements.
  • Skipping the Middle: A common mistake is forgetting to measure the midpoint of your arch. This measurement is essential for creating a symmetrical look when installing your blinds or shades. Use a level to find the midpoint accurately.
  • Neglecting the Curve: Arch windows have a distinct curvature that can't be ignored. If you measure as if it were a flat window, your blinds or shades will not fit properly. Use a flexible measuring tape or a string to follow the curve and get an exact measurement.
  • Forgetting to Account for Mounting Brackets: Mounting brackets can take up valuable space and affect the fit of your blinds or shades. Be sure to measure from the outer edge of the brackets to ensure they won't interfere with the installation.
  • Ignoring Window Frame Variations: Arch windows can have different frame styles, and the way you measure will depend on these variations. Be mindful of the frame and whether the blinds or shades should be mounted inside or outside it.

Take your time, double-check your measurements, and pay attention to the unique characteristics of your windows to ensure a perfect fit.

Tips for Accuracy

Accurate measurements are the foundation of a successful window treatment installation. To ensure that your blinds or shades fit perfectly, consider these helpful tips that will keep your measurements on point.

  • Use a Quality Tape Measure: Start with a good-quality tape measure. A flexible tape measure, designed for measuring curves, is highly recommended for arch windows. It will give you precise measurements and save you from inaccurate readings.
  • Measure at Different Points: Arch windows can have subtle variations in shape. To ensure accuracy, measure at multiple points along the width and height of the window. This helps you account for any irregularities in the arch.
  • Double-Check Your Math: After taking measurements, perform some quick math to ensure that your measurements are consistent and make sense. A little calculation error can lead to blinds or shades that don't fit.
  • Mind the Depth: Consider the window opening depth when selecting blinds or shades. Measure from the glass to the outer frame to determine the space available for mounting.
  • Take Photos: It's always a good idea to take photos of your arch window while measuring. These photos can serve as references when ordering your blinds or shades, helping you visualize how they will fit.

A little extra attention to detail can make all the difference in achieving a beautifully finished look that complements your interior decor.

Types of Blinds Suitable for Arch Windows

When it comes to dressing up arch windows, there's no shortage of options to choose from. Each type of blind or shade offers unique benefits and style, making it crucial to select the right one to enhance the beauty and functionality of your space. Here, we'll explore some of the most popular choices for arch windows:


3 1/2" Classic Curved PVC Smooth Vertical Blinds

Vertical Blinds

For larger arch windows or sliding glass doors, vertical blinds are a great option. They feature vertical slats that can be adjusted to control light and provide privacy. These blinds offer a sleek and contemporary look that's perfect for modern homes.

Contemporary Fabric Light Filtering Roller Shades

Roller Shades

Roller shades are a simple and stylish option for arch windows. They are made of a single piece of fabric that can be rolled up or down to adjust light levels. Roller shades come in various materials, colours, and patterns, allowing you to customize your window treatment to match your decor.

Check out our roller shades buying guide to learn more.

1" x 1" Classic 6g Aluminum Mini Blinds

Mini Blinds

A classic choice, mini blinds complement a wide range of interior styles. They consist of horizontal slats that can be adjusted to control light and privacy. Mini blinds can be customized to fit the shape of your arch window, providing a neat and timeless appearance.

Here's our mini blind buying guide to find out more.


1" Cordless Aluminum Mini Blinds

Faux Wood Blinds

Faux wood blinds offer the look of real wood but are more budget-friendly and resistant to moisture, making them ideal for areas with high humidity. Their durability and versatility make these blinds a popular option for arch windows, adding a touch of elegance to any room.

As opposed to real wood blinds, faux wood blinds are also more durable, resist moisture and temperature changes, and can easily be wiped clean without worrying about spills.

2" Premier Cordless Faux Wood Blinds

Cellular Shades

Also known as honeycomb shades, cellular shades are energy-efficient window coverings that can help insulate your home. Their unique honeycomb structure traps air, making them perfect for maintaining a comfortable temperature in your space.

Cellular shades can be custom-made to fit the shape of your arch window, providing both style and functionality.

We have a cellular blinds buying guide available for your reference.

3/8" Single Cellular Shade - Budget, LIght Filtering, Cordless

When choosing the right blinds or shades for your arch windows, consider factors such as your interior design preferences, the level of light control you desire, and your budget.

Whether you opt for the classic appeal of mini blinds, the warmth of faux wood blinds, the modernity of vertical blinds, the simplicity of roller shades, or the energy efficiency of cellular shades, you'll find a perfect solution to enhance the beauty and functionality of your arch windows.


Measuring arch windows for blinds and shades may seem like a challenging task, but with the right guidance, it becomes a manageable and rewarding project. We hope this step-by-step guide has provided you with the knowledge and confidence needed to ensure your window treatments fit flawlessly and enhance the aesthetics of your home.

Remember to avoid common measurement mistakes, take accurate measurements, and consider the type of blinds or shades that best suit your needs and style preferences. With a little patience and attention to detail, your arch windows will be beautifully dressed to your satisfaction.

And if you're on the hunt for quality blinds and shades, look no further than Factory Direct Blinds. With a wide assortment of options and a commitment to delivering top-notch products, you'll save time and get guaranteed quality.

Plus, if you're curious about how a particular blind or shade will look in your space, take advantage of our free samples to help you make the perfect choice!


What is the perfect arch measurement?

There is no perfect arch measurement, as it varies based on individual preferences and the specific window's design. Measure accurately for the best results.

What is a good arch?

A good arch is one that suits your aesthetic and functional needs for your window. It's a matter of personal preference.

What is a normal medium arch?

A normal medium arch typically refers to an arch window with a moderate curve or height, falling within a range that most people find visually appealing.

What is the normal range of high arch?

The normal range of high arch also depends on individual preferences, but generally, high arch windows have a more pronounced curvature or greater height compared to other arch window designs.

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