How to Measure Replacement Windows

Greetings, fellow homeowners! If you’re reading this, chances are you’re in the market for some replacement windows. It’s a big decision to make, but don’t worry, we’ve got you covered. In this comprehensive guide, we’ll go over everything you need to know about measuring for replacement windows. By the end of this article, you’ll be a measuring pro ready to tackle your window replacement project!

12 Steps to Measuring for Replacement Windows

Step 1: Identify the Window Types

The first step in measuring for replacement windows is to identify what type of windows you currently have. Are they double-hung, casement, sliding, or something else entirely? This will affect the measurements you need to take.

Step 2: Measure the Width

To measure the width, measure between the jambs at the top, middle, and bottom of the window. Use the smallest measurement as your width.

Step 3: Measure the Height

To measure the height, measure from the sill to the top jamb at the left, middle, and right of the window. Once again, use the smallest measurement as your height.

Step 4: Measure the Depth

In addition to width and height, you also need to measure the depth of your window frame. This measurement is important for ensuring that the replacement window you choose will fit snugly in the frame.

Step 5: Check for Squareness

Before ordering your replacement windows, it’s important to check if your window openings are square. If they’re not, you’ll need to make adjustments to ensure your replacement windows fit properly.

Step 6: Measure the Window Angle

To measure the angle of your windows, you’ll need to use a special tool called a protractor. This is particularly important if you have bay or bow windows.

Step 7: Determine the Window Operation

The way your windows operate (i.e. how they open and close) will also affect the measurements you need to take. Make sure you know the operation of each window before measuring.

Step 8: Measure the Glass

If you’re only replacing the glass in your windows, you’ll need to measure the size of the glass pane itself. Make sure to measure the width, height, and thickness of the glass.

Step 9: Double-Check Your Measurements

Before ordering your replacement windows, double-check all of your measurements to ensure they’re accurate. Mistakes at this stage could result in ill-fitting windows that won’t work properly.

Step 10: Choose Your Replacement Windows

Once you have all of your measurements, it’s time to choose your replacement windows. Make sure to select windows that are the right size and style for your home.

Step 11: Test the Fit

Before installing your replacement windows, make sure to test the fit. Hold the window in place to see how well it fits in the opening. Make adjustments as needed.

Step 12: Install Your Replacement Windows

Finally, it’s time to install your replacement windows. Follow the manufacturer’s instructions carefully, and don’t hesitate to call in professional help if you need it.

Now that you know the 12 steps to measuring for replacement windows, you’re ready to tackle your window replacement project with confidence. But before you dive in, here are a few additional tips to keep in mind:

Tips and Tricks for Measuring Replacement Windows

Tip 1: Measure Twice, Cut Once

This old adage is just as relevant when measuring for replacement windows. Double-check your measurements to ensure accuracy.

Tip 2: Use the Right Tools

Invest in high-quality measuring tools like a tape measure, level, and protractor to ensure accurate measurements.

Tip 3: Don’t Assume All Windows are the Same

Different rooms in your home may have different types of windows and different measurements. Make sure to measure each one individually.

Tip 4: Take Your Time

Measuring for replacement windows is a critical step in the window replacement process. Take your time and be thorough to ensure the best results.

Tip 5: Consider Energy Efficiency

When choosing replacement windows, consider options that are energy efficient to help lower your energy bills.

Tip 6: Consider the View

In addition to size and style, think about the view from your windows when selecting replacement windows.

Tip 7: Check Local Building Codes

Make sure to check your local building codes to ensure that your replacement windows meet all required standards.

Tip 8: Call in the Pros if You Need Help

Installing replacement windows can be a complex process. If you’re not comfortable doing it yourself, don’t hesitate to call in professional help.

Tip 9: Don’t Forget About Safety

When measuring for and installing replacement windows, make sure to follow all safety precautions to avoid injury or damage to your home.

Tip 10: Consider the Long-Term Benefits

Replacing your windows can be a significant investment, but it’s one that can pay off in the long run with increased energy efficiency and home value.

Following these tips and the 12 steps we’ve outlined will help ensure that your replacement window project goes smoothly from start to finish. Good luck!

Advantages and Disadvantages of Measuring Replacement Windows


1. Accurate sizes: Measuring your replacement windows ensures that you get the correct size of windows, which is essential for a proper fit.

2. Better insulation: With proper measurements, you can ensure that your new windows have a more secure fit, which helps improve their insulation, leading to lower energy bills.

3. Customizability: Measuring your replacement windows provides an opportunity to customize the design specifications of your windows, such as materials, color, and glazing.

4. Enhanced aesthetics: With proper measurements, you can choose windows that complement your home’s style and architecture, enhancing its overall aesthetics.

5. Improved home value: Measuring your replacement windows is crucial if you want to improve the value of your home. It’s a small investment that can result in significant returns when it comes to resale.

6. Increases natural light: With accurate measurements, you can choose the right-sized windows that let in more natural light into your home, creating a brighter and more inviting atmosphere.

7. Better security: Properly measured and installed replacement windows offer better security for your home, reducing the risk of theft and other security breaches.

8. Reduced noise: With correctly sized replacement windows, you can reduce outside noise infiltration, creating a more peaceful indoor environment.

9. Minimized air infiltration: Properly measured replacement windows have tight seals that help minimize air infiltration, maintaining a comfortable indoor air temperature.

10. Expert installation: When you measure your replacement windows, you can work closely with an experienced installer, ensuring a professional job that meets your unique needs and specifications.


1. Requires time and effort: Measuring your replacement windows can be time-consuming, especially if you’re not familiar with the process.

2. Inaccurate measurements may be costly: A minor mistake in measuring your replacement windows can lead to significant installation problems, which can be costly to fix.

3. Complexity: Measuring your replacement windows can be overwhelming and complex, requiring attention to detail and accuracy, which may be beyond some homeowners’ capabilities.

4. Limited DIY: Measuring replacement windows requires specialized tools and knowledge, making it challenging for the average homeowner to do it themselves.

5. No room for error: Measuring replacement windows is a precise exercise that leaves no room for mistakes. An error in the measurements can lead to installation issues, which may compromise your home’s energy efficiency, security, and aesthetics.

6. Limited design options: Measuring your replacement windows restricts you to a particular set of designs and sizes, limiting your options, especially if you’re after a unique design.

7. Dependency on a contractor: Measuring replacement windows requires assistance from a contractor, meaning you have to rely on someone else’s availability, skills, and expertise.

8. Additional costs: Measuring replacement windows is an additional cost that homeowners must bear, making it less desirable for homeowners on a tight budget.

9. Time-consuming installation: Properly measured replacement windows need to be installed precisely, which can be time-consuming, especially if your home has many windows.

10. Environmental impact: Measuring and installing replacement windows can generate construction waste, which has an environmental impact, leading to landfill buildup if not correctly disposed of.

In conclusion, measuring replacement windows has its advantages and disadvantages. It’s an essential process that ensures you get accurate sizes, better insulation, customizability, improved aesthetics, increased home value, among other benefits. However, it can be complex, require specialized tools and knowledge, and incur additional costs, among other challenges.

FAQ: How to Measure Replacement Windows

1. Why is it important to measure replacement windows accurately?

Measuring replacement windows accurately ensures that you order the right size and avoid costly mistakes. Improper measurements can cause problems such as gaps, air leaks and difficulty installing the new windows.

2. What tools do I need to measure replacement windows?

You will need a tape measure, a pencil and a notepad to write down your measurements. If you have access to a digital caliper, that can also be helpful for precise measurements.

3. Should I measure the frame or the glass?

You should measure the frame of the existing window. Do not include the casing or trim in your measurements.

4. How do I measure the width of the window?

Measure the width in three places: at the top, middle and bottom of the window. Use the smallest measurement when ordering replacement windows.

5. How do I measure the height of the window?

Measure the height in three places: at the left, middle and right of the window. Use the smallest measurement when ordering replacement windows.

6. How do I measure the depth of the window frame?

Measure the depth of the frame from the inside of the window to the outside of the frame. This measurement will help you determine what type of replacement windows will fit in your existing frame.

7. Should I measure the window from the inside or outside?

It is best to measure from the inside of the window for accuracy.

8. What if my window is an odd shape or size?

If your window is an odd shape or size, you may need to order custom replacement windows. Contact a professional to assist you with measuring and ordering.

9. How do I ensure that my replacement windows will fit properly?

Double-check your measurements and ensure that you have ordered the correct size and type of replacement windows. If you are unsure, contact the manufacturer or a professional for assistance.

10. What if there are obstructions or moldings around my window?

If there are obstructions or moldings around your window, be sure to measure the frame only and not include them in your measurements.

11. How do I measure for replacement windows in a multi-pane window?

Measure the width and height of each individual pane, including any dividers or muntins between them. Add up the measurements to determine the total size of the window.

12. How do I measure for replacement windows in a bay or bow window?

Measure each window in the grouping separately and order replacement windows accordingly.

13. What should I do if my measurements are incorrect?

If your measurements are incorrect, contact the manufacturer or professional installer immediately to correct the issue before installation.

How to Measure Replacement Windows

Replacing windows is a common home improvement project. A new set of windows offers both aesthetic and energy efficiency benefits. Replacing your windows gives you the opportunity to upgrade to more energy-efficient windows, improve your home’s curb appeal, provide your home with better insulation, and increase your home’s value. It is essential to get the window measurements right before you start the installation process. In this article, we will discuss how to measure replacement windows properly.

Conclusion and Closing

Now that you know how to measure replacement windows, you can proceed to purchase the right size of windows for your home. To make sure that you measure accurately, use the right tools, and take your time during the process. If in doubt, it’s better to seek professional installation assistance. Replacing windows is a significant investment, and you want to make sure you get it right. When done correctly, window replacement can improve the overall function and aesthetic of your home. We hope this article has helped you with your window measurement process.

Good luck with your replacement window project and happy measuring!