How to measure for replacement windows?

How to measure for replacement windows


Frame-to frame

It may seem that is easy to measure your windows if you want to replacement them yourself but in practice it can be difficult and time consuming. One of the popular ways to measure your window size is by measuring the frame of your window. However, measuring the frame can be cumbersome because usually the frame is buried under the casing/trim of the window on the inside of your home. There are two ways you can measure the frame of your windows from inside the use.

First way, is to remove the trim of the window from the inside and then measure the frame from the edge to edge, from left to right. You won’t have to remove both casings, if you remove only one trim you can estimate where the other edge of the frame maybe under the casing. After you have measure from left to right, it is time to measure from bottom up. After having measured your windows, you will have two numbers like in this example: 26 x 40. The first number is the width of your window and the second number is the height of the frame of your window.

The second way of measure for replacement window is to measure without removing the casings. As a general rule of thumb is that the edge of your frame is located in the middle of the casing/trim of the window. This rule is mostly true for most houses in Manitoba. Follow the same steps as above by measuring from the middle of the casing without removing the casing from left to right and then repeat the same steps from bottom up. You should have approximately the same results as above, in this example 26 x 40 inches.

Frame to frame measurement


A more accurate way of measure your window without removing any trims or casings, would be to measure them from the outside. Your windows on the outside should have clear borders that are called brickmoulds. Measure your windows from the edge of the brickmould from left to right and right down that number. Repeat the same steps from the bottom of your window’s brickmould to upper brickmould. Now, this number will be bigger than your measurements from inside the home. Your windows may have different brickmould size on the outside, and if for example your windows have a brickmould of 2 inches, then your windows will measure 30 x 44. If you notice, these numbers are 4 inches more than when you measured frame to frame. That’s because the brickmould on the outside of the window, goes around the frame and adds to the window size.

Brick to brick measurement


Wall thickness

Now that you have measured your windows, it is also important to measure the depth of your windows. Measuring from left to right and from bottom to upper frame is a good start but you also need to know how thick your wall is. Image your wall is about 7 inches thick and your new windows are only 3 ¼ inches thick. You will have about 3 ¾ inches of bare wall that you will have to cover somehow. The best way to measure the thickness of your wall is by opening your window and measuring the thickness of your wall. Try to align your measuring tape to the inside of your wall and run the tape out the window until you cover the whole depth of the wall. Now you have an approximate measurement of your wall.

Some old windows may not open at all. If your window is too old or if the crank opener is broken and there is absolutely no way for you to open your window to measure your wall, then you can use your entrance door to do the job. Open your door and find the frame of your door. Measure the depth of your door from left to right. Usually, door depths are about 4-6 inches in Manitoba but you may get different numbers. Whatever is your number, that is the depth of your door frame and most likely that would be the depth of your wall as well.

Your new window will likely come in a 3 ¼ inches of width and if you have measured your wall’s thickness as 6 inches, then you most probably will need a window extension to cover the portion of the wall that your window didn’t cover.


Of course, it is a good idea to measure the windows yourself but you really don’t have to. Most companies in Manitoba offer Free Estimates and that includes coming to your home and measuring your windows for you. Arctic Star Windows provides absolutely Free and no obligation in home quotations and we provide accurate measurements of your windows for free. Save your time and contact us to get this job done professionally.