11 Window Measuring Mistakes + How to Avoid Them

The average house owner may think that measuring your windows and ordering blinds online to install yourself would be a fantastic way to save money and handle their installation, although this is true to some extent, there are many things to be aware of. There are several mistakes that even most homeowners make daily. That is why we have compiled the top mistakes that one may make when measuring windows as well as how to avoid these mistakes.

1. Not Taking Measurements of the Windows

We spoke to a representative from Reynolds Blinds who deals with Birmingham Blinds and knows a lot about blinds, they said, to accurately measure windows, tape the window frame around the whole window opening. Keep in mind that you shouldn’t measure the size of the blinds that you believe will fit in those windows. It is necessary to measure the real windows since each kind of window furnishings has its specific spacing as well as fitting requirements, which will be taken into consideration by the blind designers and installers when designing and installing blinds based on those measurements. Even the most opaque roller blinds contain tiny holes to enable them to move smoothly in their tracks.

This occurs all too often when someone purchases new blinds to replace existing blinds and submits the old blinds’ dimensions.

2. Assuming that similar-looking windows are the same size

Occasionally, you will have 2 or even more windows that may seem to be the same size due to the way they are displayed. It’s important not to make this assumption whenever measuring your windows. Every single window should be measured. There are frequent variances that necessitate the re-cutting of one or more of the blinds.

The second component of this error is the assumption that all windows are rectangular, while some windows may be slightly slanted to one side or the other of the room. To prevent making this error, take three measurements of each dimension.

3. Measuring the size of your blinds based on your preferences rather than the size of the window opening

Occasionally, when ordering inside-mount window coverings, individuals may make their dimensions slightly smaller in the mistaken belief that their blinds must be a little smaller to accommodate in the window. A lot of individuals make these mistakes, which may result in blinds that are too small or too large for their windows.

You are correct in assuming that your blinds should be a fraction of an inch smaller than that of the window. However, each kind of blind, as well as shade, requires not only a different height but also width deductions to be properly installed. Make sure to do all of the necessary computations to keep things as easy as possible for you.

Please keep in mind that the procedure for measuring exterior mount window coverings is different.

4. Forgetting to Measure Depth

When buying window fittings on the internet, even the most experienced hardware enthusiast may commit this common mistake. While measuring blinds, it is essential to take into consideration the depth of your window sills to prevent making unpleasant errors. Read – How To Remove Wallpaper? Full Guide

5. Using an Inadequate Tape Measure

Using a steel tape measure is the most accurate method of measuring windows. They are not intended for measuring straight lines precisely, and they are prone to making mistakes with their soft curly sewing measures. Make use of a high-quality tape measure and avoid bending it while determining the precise length. However, allow the measuring tape to rest flat on the surface and multiply the number on the measuring tape by the measurement of the tape measure housing, which is typically printed on the side of the measuring tape.

6. Making Measurements with Old Blinds Rather Than the Window Opening.

Certain individuals believe that by measuring the existing blinds in their window, they will get the same size. The dimensions, on the other hand, are dependent on the window opening and would be too small if you do it in this manner.

Furthermore, don’t make the mistake of assuming that you’ll be able to reuse the old brackets or that you’ll be able to quickly measure the distance between the brackets. Always measure from edge to edge of the window aperture.

7. Not Measuring in Three Different Places

Another critical objective is to measure the height and breadth in three different locations – the top, center, and bottom – to ensure that the measurements are accurate. Even when the top and bottom of your windows are different sizes, you can be certain that your blinds will fit in both locations. In the same way that no two windows are the same size, it’s uncommon to come across a completely square window.

Even though your windows are tall as well as the top is out of grasp, it’s still essential to acquire a ladder and take measurements at the very top. It would be a shame to miss this step and end up with blinds that don’t fit.

8. Not Increasing the Width of Outside-Mounted Blinds

The method of measuring for outside-mount blinds is somewhat different. It is in this instance that you will not measure the size of the window opening, but instead the precise size that you want the finished product to be.

You must make the blinds somewhat wider as well as higher than that of the window opening since you will be mounting them on the wall above the window outside the aperture. We suggest going at least 2″ broader on each side of the aperture, for a total of 4″ in width. Aim for the window sill and measure up to approximately 3 inches above the window trim (to accommodate installation brackets).

Unless you include these additional inches, your window covering could have spaces on the sides where light comes through but it might not cover the whole window sill if you don’t include them.

9. Experimenting with different widths and heights

You would not believe how many times individuals order the incorrect size blinds just because they get the width and height measurements mixed up.

Using a Measuring Guide and double-checking your measurements are two simple ways to prevent making this mistake. Furthermore, make a note of the measurements at all times. Also Read – How Much Does It Cost to Furnish a House? A Price Guide

10. Failing to double-check your measurement results

Before placing your purchase, it’s always a smart option to double-check your measurements to be sure they’re accurate. “Measure twice, cut once,” as the saying goes in the construction industry. If you’re ordering blinds online, double-check that you read the tape measure properly, took measures in 3 locations, choosing the correct measurement from the 3, and also didn’t switch up width and height.

11. Bending the Tape Measurement

When it comes to measuring within an aperture (such as your window), you might believe that the only method to do so is to bend the measuring tape and estimate which tick point is in the center of the curve.

Rather, we’d like to share a little secret with you. On the back of your measuring tape, you should see a tiny number. This will provide you with the precise dimensions of the measuring tape housing.

A low-quality and much less accurate measuring tape may not have a number like this on the side of the tape measure case. It’s worth it to spend a little more money and get a name-brand one. This will come in useful for a variety of future tasks.


Although measuring windows might seem like an easy task, a lot of mistakes usually happen. It is important to be aware of all three mistakes as well as how to avoid them. As a result of all of this, you should be able to properly measure for blinds and obtain a great fit every time.