How to Measure for a Window: Essential Guide for Homeowners

Welcome to our article on “How to Measure for a Window”. If you’re planning to install new windows or replace old ones, it’s important to get the right measurements to ensure a perfect fit. Measuring for a window might seem like a straightforward task, but it requires accuracy and attention to detail. In this article, we will outline 12 steps to follow when measuring for a window, as well as provide some additional tips and tricks to make the process easier and more successful.

Steps to Measure for a Window

Step 1: Determine the Type of Window

Before you begin measuring, it’s important to know the type of window you will be replacing or installing. Whether it’s a double-hung window, bay window, or casement window, understanding the shape and size of the window opening is essential to ensure accuracy in your measurements.

Step 2: Remove Old Windows (if applicable)

If you’re replacing old windows, removing them can provide a clear view of the opening and make measuring easier. Make sure to remove any screws or nails holding the window frame in place and gently remove the window from the opening.

Step 3: Measure the Width of the Window Opening

To measure the width of the window opening, measure the distance between the inside of the window frame on each side of the opening at its widest point. Make sure to measure across the top, middle, and bottom of the opening and record the widest measurement to ensure a proper fit.

Step 4: Measure the Height of the Window Opening

To measure the height of the window opening, measure the distance between the inside of the window frame at its highest point and its lowest point. Measure at the left and right sides of the opening, as well as the center, then record the longest measurement.

Step 5: Measure the Depth of the Window Opening

The depth of the window opening is the distance between the inside of the window frame and the exterior wall. This measurement is crucial to ensure that the new window will fit properly without any gaps or overhangs.

Step 6: Determine the Window Style and Opening Requirements

Different window styles have different opening requirements, and it’s important to know these requirements when measuring for a window. Casement windows, for example, require more space for opening and closing, while double-hung windows require less.

Step 7: Consider the Window Frame

The frame of a window can also impact its dimensions and affect how it fits in the opening. Make sure to consider the size of the frame when measuring, especially if you’re installing a new window with a different frame size than the previous one.

Step 8: Measure for Window Sliders (if applicable)

If your window has sliders, measure the distance between the grooves where the sliders sit on each side of the opening. This will ensure that the new window sliders fit perfectly in the existing grooves.

Step 9: Take Note of Obstructions

Obstructions such as pipes, electrical outlets, or window latches can affect the placement and size of the new window. Make note of any obstructions and measure around them to ensure an accurate fit.

Step 10: Take Multiple Measurements

To ensure accuracy, take multiple measurements of the window opening and record the largest measurement of each dimension. It’s also a good idea to measure the diagonals of the opening to ensure that it’s square.

Step 11: Check for Levelness and Plumbness

Once you have the measurements, check to see if the window opening is level and plumb. A level opening ensures a proper fit and easy installation of the window.

Step 12: Double-Check Your Measurements

Before ordering or purchasing your new window, double-check your measurements to ensure their accuracy. If possible, have a professional take a look at your measurements to confirm that they are correct.

Additional Tips and Tricks

Tip 1: Use a Measuring Tape

When measuring for a window, use a measuring tape instead of a ruler or yardstick. Measuring tapes offer more precise measurements and flexibility.

Tip 2: Measure Twice, Cut Once

Double-check your measurements to prevent costly errors and ensure a perfect fit.

Tip 3: Take Measurements from Inside the Home

Measure from inside the home to ensure that your measurements account for the thickness of the exterior walls.

Tip 4: Understand Standard Window Sizes

Understanding standard window sizes can make the process of measuring for a window easier and help you select the right window for your needs.

Tip 5: Consider Window Treatments

If you plan to install window treatments such as blinds or curtains, make sure to consider their size and placement when measuring for your new windows.

Tip 6: Take Your Time

Measuring for a window requires accuracy and attention to detail. Take your time and be patient to ensure the best results.

Tip 7: Don’t Forget the Sill

When measuring for a window, don’t forget to measure the depth and width of the sill. This will ensure that the new window fits properly on the sill.

Tip 8: Consult a Professional

If you’re unsure about your measurements or have any questions about the window installation process, consult a professional for guidance and assistance.

Tip 9: Measure On a Cloudy Day

Measuring on a cloudy day can minimize glare and provide better visibility, making it easier to measure accurately.

Tip 10: Label Your Measurements

Label your measurements with clear and concise labels to ensure that you don’t mix them up or forget which measurement belongs to which dimension.

In conclusion, measuring for a window requires accuracy, patience, and attention to detail. These 12 steps and additional tips outlined above can make the process easier, less stressful, and more successful. Take your time, double-check your measurements, and if needed, consult with a professional window installer to ensure that your new windows fit perfectly and enhance the beauty and functionality of your home.

How to Measure for a Window: Advantages and Disadvantages


1. Accurate measurement: Measuring for a window ensures that you get an accurate measurement of the window opening where the window will be installed. This prevents errors in measurement that can lead to purchasing the wrong window size.

2. Proper fit: Accurate measurement ensures that the window will fit perfectly and will not allow drafts into your house.

3. Saves time and money: Taking the time to measure for a window saves you the cost of returning a wrongly sized window and having to go through the process again.

4. Professional installation: With accurate measurements, you can hire a professional installer who will fit the window perfectly into the opening.

5. Sizing options: Precise measurements offer a variety of window sizing options to choose from.

6. Energy efficiency: Properly measured windows may help reduce energy bills by allowing for better insulation and preventing heat or cool air from escaping.

7. Visual appeal: Having a properly measured window lends a professional air to the house and increases the house’s curb appeal.

8. Versatility: Correctly measuring the window opening allows window options from different manufacturers to be considered and selected.

9. Improved natural lighting: The correct window size can let more natural light in and brighten the room, which can create the illusion of greater space.

10. Resale value: Accurately measured and installed windows can increase the value of the home when selling.


1. Extra work: Measuring for windows takes extra time and effort, which can be a disadvantage for people who would prefer a quicker solution.

2. Require tools: Measuring requires tools, like a measuring tape, which can make it challenging for people without appropriate tools.

3. Reduced ability to adjust: Once the window is measured and installed, it may be harder to make small adjustments or modifications.

4. Human error: Measurement errors are common and can lead to purchasing the wrong window, which leads to additional cost and frustration.

5. Incorrect installation: Even with correct measurements, it is possible for windows to be installed poorly, which may require additional fixes and expenses.

6. Unforeseen issues: Measuring for a window may not anticipate unforeseen issues with the window opening, like uneven frames, which makes installation more challenging.

7. Limited flexibility: Measuring may limit the type of window that can be installed, which may not meet the homeowners’ aesthetic or functional preferences.

8. Noise reduction: Without special windows, measuring for windows may not reduce outside noise as well as other solutions like insulation or window coatings.

9. Additional expenses: Hiring a professional to measure and install the windows can add further expense to the project.

10. No return policy: If windows are accurately measured but not installed correctly, it may not be possible to return the product for a refund.


1. How do I measure for replacement windows?

First, measure the width of the window from edge to edge at the inside of the frame. Next, measure the height of the window from the top to the bottom at the inside of the frame. Take these measurements at three separate points: at the top, middle and bottom of the window. Use the smallest of the three measurements for the width and the height.

2. How do I measure for new windows?

If you need to measure for new windows, start by measuring the width and the height of the window frame. Make sure to measure the frame at its widest points, including the interior casing and the exterior moulding.

3. Do I need to remove the window to measure it?

No, you do not need to remove the window to measure it. Simply measure the width and height from the inside of the frame.

4. How much extra space should I leave for a replacement window?

When measuring for a replacement window, you should add an additional 1/4 inch to the width and height of the old window opening to allow for any shifting or settling of the frame over time.

5. How do I measure for a bay window?

When measuring for a bay window, you need to measure the width and height of the opening as well as the space between the inside and outside walls. This will help you determine the correct size of each window needed for the bay window.

6. How do I measure for a bow window?

When measuring for a bow window, measure the width and height of the opening as well as the depth from the inside to the outside wall. You will need to measure this depth at least three times at different points to ensure accuracy.

7. What tools do I need to measure for a window?

All you need to measure for a window is a tape measure. Make sure to use a sturdy tape measure that can reach the entire length of the window opening.

8. What kind of measurements do I need for a custom window?

For a custom window, you will need to provide exact measurements for the width, height, and thickness of the window frame.

9. Should I measure in inches or centimeters?

It is recommended to measure in inches when measuring for windows because most windows are measured in inches. However, if you prefer to use centimeters, just make sure to convert them to inches before ordering the window.

10. How do I measure for a window with a curved top?

To measure for a window with a curved top, start by measuring the width and height of the rectangular part of the window. Then, measure the radius of the curve and measure from the top of the rectangular part to the highest point of the curve.

11. How do I measure for a window with an arch?

To measure for a window with an arch, take the width and height of the rectangular part of the window, as well as the height of the arch at its highest point. Measure the arch height at the center and from left to right.

12. Can I measure for windows on my own, or should I hire a professional?

Measuring for windows can be done on your own, but if you are unsure or want to ensure accuracy, it is best to hire a professional to measure for you.

13. What if my measurements are not standard?

If your measurements are not standard, consider ordering a custom window or contacting the manufacturer to see if they offer any non-standard sizes.

How to Measure for a Window

Measuring for a new window might seem like a simple task, but it can quickly become overwhelming if you don’t know what you’re doing. Getting the correct measurements is crucial to ensuring that your new window fits correctly and functions properly. In this article, we will give you step-by-step instructions on how to measure for a window.


Measuring for a window is not as daunting as it may first seem. With a bit of patience, accuracy, and the right tools, anyone can successfully measure for a new window. Following the simple steps outlined in this article will ensure that you get the correct measurements and a perfectly fitting window for your home. Remember, the success of your window installation depends on the accuracy of your measurements, so take the time to measure carefully and precisely.

Thank you for reading this article on how to measure for a window. We hope that you found it informative and helpful. Good luck with your window installation project!