How do I Measure the Size of My Windows to Install Blinds?

Whether you are just moving into a home or your blinds need refreshing, talented homeowners can save money by performing a DIY blind installation.

How Do I Measure the Size of My Windows to Install Blinds?

Whether you are just moving into a home or your blinds need refreshing, talented homeowners can save money by performing a DIY blind installation. If you want to attempt your blind installation process solo, we advise carefully following these guidelines for window measurement. If, however, by the end of this article you would like a hand with blind installation and window measurement, you can call on the experts at The Blind Guy.

How Do I Measure the Size of My Windows?

Before you whip out that measuring tape, the first aspect of blind installation you must consider is the type of blind you will get: inside or outside mount blinds. Inside mount blinds are installed in the window frame, allowing for a more seamless, minimalist aesthetic. However, this style will allow light to peek through the very edges, so it is not recommended for those looking for a total blackout blind. In that case, it would be better to have outside mount blinds. These blinds are mounted above the window or right on the trim, covering the entire window casing and preventing any light from sweeping through. 

Once you know which blinds you want, you will need to follow the unique measuring guidelines to ensure the proper fit. 

inside mount measurement the blind guy

Inside Mount Blind Measurements:

When pursuing a window measurement for inside mount blinds, you will want to start with the width. Start by measuring the inside width of the window frame in three spots: the top, middle, and bottom. You will want to use the smallest measurements as well as your reduction when submitting your final numbers.

Next, to measure the length, you will again want to measure in three places: the left side, the middle, and the right side. As a note, if you want your blind installation to rest just above the sill rather than sitting right on it, you will want to remove 1/4 inch from the total. Alternatively, if you prefer the more extended look, you will want to add the appropriate amount of inches to ensure the bling rests where you want it to. Keep in mind that while having a blind be extra long can be a unique style, it has a greater probability of getting dirty or broken.

Lastly, you will need to measure the depth of the window casing. We recommend measuring the upper window casing depth as it will be there the blind installation occurs. Keep in mind when ordering your blind supplies that some blinds do have a minimum requirement for mounting, and others do not. Make sure to double-check those numbers before ordering. 

How Much Smaller Should Blinds Be Than a Window?

The above measurements give you the exact size width of your window, but that won’t work for your blinds. If you submit the exact size, the blinds won’t fit into the window casing. Instead, after you take your initial measurements for your window width, you will want to take the narrowest measurement and round down to the nearest 1/8 inch. The industry standard is to take between 1/4- inch to 3/8- inch deduction to ensure the proper blind sizing. 

Note: This only applies to the width of the window. Length reduction will depend on style preferences, and there should never be a depth reduction. 

outside blind installation expert installing curtain blind

Outside Mount Blind Measurements 

When determining an outside mount window measurement, we will follow a similar process as with inside mount blind measurements. 

First, measure the width of the window. To do this, you will measure from one outside trim to the other in three places: top, middle, and bottom. You will keep the widest measurement.

Second, to find the length of the window, you will take measurements in three places: the right outer edge, the center, and the left outer edge. Again, you will keep the largest number. 

Unlike inside mount blinds, you do not need to take a depth measurement since the blinds will be installed above the window casing rather than inside. 

How Much Larger Should Blinds be Than the Window?

While inside mount blinds need to be smaller than the window casing, outside mount blinds need to be larger to keep out every possibility of light. Depending on your aesthetic preferences, we recommend adding anywhere from ½-inch to 3 inches in width on either side. The industry standard is to add 3.5 inches or more for length since you will be completing the blind installation above the window. 

Essential Tips to Keep in Mind When Measuring for Blinds

Even the best DIYers make mistakes. Therefore, we recommend carefully utilizing these tips to ensure you get accurate measurements.

First, we recommend using a high-quality steel measuring tape. Do not use flimsy fabric tapes or a yardstick to measure, as they won’t produce the proper answers. Additionally, if it has been a while since you have taken a measurement, give yourself a quick refresher course on how to read a measuring tape before you start writing down numbers. 

Second, always take multiple measurements. It is vital to remember that most window casings aren’t perfectly square. Therefore, you need to take multiple measurements from different angles AND repeat those measurements two or three times to ensure you got it right. We recommend measuring each window casing as suggested above and then doing it another two times with breaks in between. Don’t use the same paper; use a different notepad to write down the measurements and compare. If you are ever off, do it another two to three times. 

the blind guy of tri cities blind installation crew

Should I Hire a Professional for My Blind Installation?

For some crafty homeowners, DIYing blind measurements and installation may be possible. However, we want to caution that a single incorrect measurement can mean that your blind will not fit, which is an expensive and time-consuming mistake to fix. Additionally, homeowners often make mistakes during installation that can damage their brand-new blinds and window casings. If you are at all hesitant, we recommend hiring a professional. They can quickly and efficiently take proper measurements of your window casings, offer aesthetic recommendations, suggest brands that will work best for you, and complete the installation promptly and beautifully. 

The Blind Guy of Tri-Cities is dedicated to providing our local customers with premier window coverings. You can rely on our experienced staff to measure, design, and install beautiful, long-lasting products from our top manufacturers. To make a consultation appointment, please complete our contact form.