Windows come in all shapes and sizes. Whether you’re measuring for replacement windows or need the right blinds or curtains to bring a room together, accurate measurements are everything.
The wrong size replacement window can lead to window gaps. Gaps can cause air leaks, which account for up to 40% of the energy used to heat and cool a home, according to Energy Star, and water leaks that damage the floors and walls.
Here’s how to measure windows for the best-fitting replacement window, blinds or shades.
— Tips on how to accurately measure windows.
— How to measure windows: step-by-step process.
— DIY vs. professional window replacement.
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Tips on How to Accurately Measure Windows
Measuring windows only requires a tape measure that measures to the one-sixteenth of an inch, a pencil and some paper.
“Write down each measurement immediately after taking it; if in doubt measure it again and utilize a helper if available,” says Dan Jacobs, vice president and general manager of windows for JELD-WEN North America. “Also, consult the window manufacturer’s instructions, as most provide detailed measuring and installation instructions on their websites.”
How to Measure Windows: Step-by-Step Process
Whether you’re replacing your windows or need to find perfect-fitting blinds or shades, you will need accurate window measurements.
“The measurement process varies across window types,” Jacobs says. “However, to cover the widest variety, take measurements on the exterior horizontally and vertically from the outermost edge of the window frame.”
You should also make sure that there are no existing problems, such as wood decay or water leaks, around the existing frame if you plan to replace the window. Simply replacing a window won’t fix these underlying issues.
Here is the step-by-step process to accurately measure windows:
1. Check the Squareness of the Window
Before you pick out a screen or a replacement window, you need to make sure your window frames are in square, which means all four corners come to a 90-degree angle. If you install a replacement window in a frame that is out of square, then the window might not open.
To check the squareness of the window, you will need to measure diagonally across each side.
1. Take your tape measure and hold it at the top right corner where the trims meet and measure diagonally to the bottom left corner.
2. Take the tape measure and hold it at the top left corner where the trims meet and measure diagonally to the bottom right corner.
3. Compare these measurements. If there’s more than one-quarter of an inch difference, then the frame is out of square and you made need to make adjustments to the frame or replace the frame altogether.
2. Measure the Width of the Window
To measure the window’s width, you will need to take three measurements.
1. To measure the bottom of the window, raise the window sash, which is the part of the window that moves up and down and holds the glass, to expose the window jambs, or sides of the window. Measure the width of the window from the side jambs. The jambs are the vertical parts that form the sides of the frame.
2. To measure the middle of the window, close the window and extend your measuring tape from jamb to jamb.
3. To measure the top of the window, close the window and measure from jamb to jamb. Like with the bottom of the window, you may need to move the sash (opening the window) to have full access to the jambs on each side.
4. The shortest measurement of the three is the width of the window.
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3. Measure the Height of the Window
To measure the height of the window, you will need to take three more measurements from the window sill. Keep in mind that the window sill is the flat part of the trim at the bottom of the window and not the stool, which is the piece of wood attached to the sill.
1. Open both window sashes and thread the tape measure between the sashes.
2. From the top, measure from the head jamb, or horizontal piece that makes up the top of the frame.
3. At the sill, measure to the top of the sloped sill on the exterior side.
4. Measure the height from the left side of the window, the right side of the window and the middle.
5. The shortest measurement of the three is the height of the window.
4. How to Measure for Storm Windows
Measuring storm windows is similar to measuring single- and double-hung windows. Using the same steps above, measure the height and width of the window to determine the size of the storm window.
5. How to Measure for Window Screens
If a screen is being added to a window that does not currently have one, you must:
1. Measure the horizontal distance between the screen channels on the frame. Subtract one-eighth of an inch from the measurement to determine the width dimension.
2. Measure the height by first raising the window sash and measuring up from the lip, which holds the screen in place, along the channel to the sash. Add one-eighth of an inch to the measurement to determine the height dimension.
If you are replacing an existing screen, measure the screen’s width and height. This will tell you the necessary dimensions for the replacement window screen.
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DIY vs. Professional Window Replacement
“While window replacement can be done by DIYers with technical aptitude and a moderate-to-advanced level of skill, we recommend you work with a professional when installing windows,” Jacobs says. If you do choose to do it yourself, Jacobs recommends closely following the manufacturer’s installation instructions and brushing up on basic weatherproofing methods to ensure the success of your window’s performance.
If you do hire a professional to install replacement windows, they will take their own window measurements as part of the job. “They generally have a better understanding of window offerings, how to determine specific configurations of a window and local building codes to make sure you are ordering the right product for your job,” Jacobs says. “Potentially, the best aspect of a company representative taking measurements, versus the DIYer, is the burden of responsibility. In most cases, a mismeasure would fall on the person who did the measuring.”
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How to Measure Windows originally appeared on usnews.com
Update 02/16/23: This story was published at an earlier date and has been updated with new information.
