If you are starting to research new windows, the first thing any contractor—including us—will ask is: “How many windows are we looking at, and roughly what size are they?” Knowing how to measure windows for replacement is the best way to get an accurate initial estimate and helps you understand the scale of your project before a professional even sets foot in your Oak Brook home.

While our team at Quantum Exteriors always performs a final, laser-accurate measurement before ordering your custom units, these DIY steps will give you the confidence to start shopping for the best fit for your Chicago area home.

Tools You’ll Need

• A sturdy metal measuring tape.

• A notepad and pen.

• (Optional) A step ladder for higher windows.

The Rule of Three: Measure for Accuracy

Windows are rarely perfectly square, especially in older Chicago bungalows. To get the most accurate number, you should always measure in three places for both width and height.

1. Measure the Width

Measure the horizontal distance between the inside of the window jambs (the vertical sides of the frame).

• Measure at the top, the middle, and the bottom.

• Circle the smallest of the three numbers. This is your width. You want the window to fit in the narrowest part of the opening.

2. Measure the Height

Measure the vertical distance from the high point of the sill (the part closest to the inside) to the top of the window opening.

• Measure at the left side, the center, and the right side.

• Circle the smallest of the three numbers. This is your height.

3. Measure the Depth

This is often overlooked but critical for Oak Brook homeowners choosing between pocket and full-frame installation. Open the window and measure the depth of the frame from the outside trim to the inside trim. You need at least 3 ¼ inches of depth for most standard replacement windows.

Important: Don’t Include the Trim

One of the biggest mistakes homeowners make is measuring the decorative wood trim (casing) around the window. Do not include the trim. You are measuring the “opening” that the window sits inside. If you include the trim, your measurements will be several inches too large, leading to an inaccurate quote.

How to Record Your Measurements

In the window industry, measurements are always listed as Width x Height.

Example: If your width is 36″ and your height is 60″, your window size is 36 x 60.

Conclusion: You’ve Got the Numbers, Now Get the Quality

Now that you know how to measure windows for replacement, you are ready to take the next step. Whether you have 3 windows or 30, having these rough numbers helps us provide a much faster and more accurate preliminary quote for your Oak Brook or Chicago home.

Ready to turn those measurements into a reality? Schedule a Free Inspection Now and we’ll verify your numbers for a perfect fit. Want a quick estimate based on your measurements? Get a Free Quote Today. Looking to save? Claim $500 Off Your Project.