Step-by-Step Guide: How to Measure Windows for Replacement

Replacing a window is an intimidating task, but it doesn’t have to be. With the right tools and knowledge, you can measure for a replacement window in just a few simple steps. Whether you need to replace single or double-hung windows, this step-by-step guide will walk you through the entire process from start to finish so that you can have your new windows installed in no time. So don’t worry—measuring for replacement windows isn’t as hard as it seems. Let’s get started!

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Disclaimer: This guide is intended to provide general information and guidance on how to measure windows for replacement. It is not intended to be professional advice, nor should this guide be used as a substitute for consultation with an experienced window installer or contractor. With years of experience in the Spokane, WA area, Advance Roofing LLC has been proudly providing high-quality roofing solutions with the utmost care and expertise. We are always happy to help!

Definition of Replacement Windows

Replacement windows are windows designed to fit into existing window frames. They’re a great option for homeowners who want to upgrade their windows without needing to do major renovations. Replacement windows come in a variety of styles, sizes, and materials, so you can find the perfect one for your home. Whether you want new single or double-hung windows, casement or awning windows, picture or bay windows—there’s something for everyone. With replacement windows, you can enjoy the benefits of energy efficiency and improved insulation without having to completely replace your existing window frames. Plus, you can choose from an array of colors and finishes that will perfectly complement your home’s style. And since they’re made to fit into existing frames, installing them is often easier than traditional window installation methods. With replacement windows, you get all the advantages of new windows in less time and with less hassle.

Replacement windows are a great solution for those looking to upgrade their windows without the hassle of a complete overhaul. So if you’re ready to reap the benefits of energy-efficient and well-insulated windows, consider getting replacement windows today! Ready to take your window installation project one step further? Discover the purpose of accurate measurement in our next section!

Purpose of Accurate Measurement

Accurate measurement is essential for getting the perfect fit when installing replacement windows. Taking the time to measure each window correctly will ensure that your new windows are properly sized and positioned, so you won’t have any gaps or misalignment after installation. Plus, measuring accurately can help you save money on costly replacements down the line. To get the best results from your replacement windows, make sure to take precise measurements of each window before ordering.

When measuring for replacement windows, it’s important to consider the height, width, and depth of each window opening. If you have double- or triple-hung windows, measure both sashes separately—this will help ensure a proper fit when they are installed together in the frame. Additionally, make sure to measure diagonally across each corner and check that all four measurements match up—if they don’t, then there could be a problem with your window frames or structure. It’s also important to record any obstructions or irregularities in the space around your existing frames so that you can order properly sized windows with clearance to fit them in place during installation.

By taking accurate measurements of your existing window frames before ordering replacement windows, you can save yourself time and money down the line! With precise measurements in hand, you’ll be well on your way towards enjoying all the benefits of having energy-efficient and well-insulated replacement windows in no time!

Step 1: Preparation

The first step in measuring windows for replacement is preparation. Before you begin taking your measurements, it’s important to make sure the area is clean, clear of any obstructions, and easy to move around in. Remove any window treatments or hardware that might be blocking the view of your window openings. If you have double- or triple hung windows, lower both sashes separately so that they are fully open and exposed for measurement. Additionally, be sure to record any irregularities or obstructions in the space around your existing frames—this will help ensure a proper fit when you order your new windows. Once you’ve completed the necessary preparations, you’re ready to start measuring!

Once you have the area prepped, you’re ready to start taking the measurements necessary for a successful window replacement. Now that you know what to do, it’s time to gather the necessary tools – and that’s where we’ll pick up in the next section!

Gather the Necessary Tools

Before you begin measuring your windows for replacement, it’s important to make sure you have the right tools. A good tape measure is one of the most essential items – you’ll use it to take all of your measurements. It’s also helpful to have a pencil and paper handy so that you can accurately record them. If your window has any obstructions that aren’t easily visible, such as trim or molding, a level may come in handy so that you can determine if they are level or not. Finally, if you’re replacing multiple windows at once, consider investing in a chalk line so that all of your frames are perfectly aligned with each other. With these simple tools in hand, you’re now ready to start taking measurements!

Gather the Necessary Tools

Clear the Area Around the Window

It’s important to make sure the area around your window is cleared before you begin taking measurements. This will give you plenty of room to work, and it will also help ensure that your measurements are accurate. Start by removing any furniture or items from in front of the window. Then, check for obstructions such as trim or molding that may impact your measurements. If there are any, use a level to determine if they’re even with the frame or not – this information can be helpful for getting an exact measurement. Finally, make sure the area is free of dust and debris so that you can measure without obstruction. With everything cleared away, you’re now ready to start measuring!

Remove Existing Window and Trim

Removing an existing window and trim can be a tricky task, especially if you don’t have the right tools or experience. However, with some preparation and care, you can successfully remove your window and trim. Start by removing any hardware from the window frame, such as screws or nails. Then, use a pry bar to carefully remove the trim pieces from around the window frame. If necessary, you can also use a chisel to gently loosen any stubborn pieces of trim. Finally, you’ll need to unscrew the window itself from the frame – be sure to wear protective gloves for this step! Once all of the pieces have been removed, you’re ready to start installing your new window and trim.

Step 2: Determine Size of Original Window

After you’ve removed your existing window and trim, the next step is to determine the size of the original window. You’ll need to measure both the width and height of the opening in order to get an accurate measurement. To start, use a tape measure or ruler to measure from one side of the opening to the other. Then, measure from the top of the opening down to the bottom. It’s important to be as precise as possible when measuring, so double-check your measurements against each other before writing them down. Once you have your measurements written down, you can compare them with standard window sizes and find a new window that matches your exact size.

Now that you have the measurements of your original window, you’re ready to move on to finding the perfect replacement. With this knowledge in hand, you’ll be able to make sure your new window fits perfectly in its place. Next up: measuring the width and height of the left corner, right corner, and top center of your window jambs – stay tuned!

Measure Width and Height of Left Corner, Right Corner, and Top Center of Window Jambs

Once you have the measurements of your window opening, it’s time to get more precise with your measurements. To do this, you’ll need to measure the width and height of the left corner, right corner, and top center of your window jambs. These measurements will help ensure that your new replacement window fits properly in its place.

To begin, start measuring from the left corner of the jamb and measure across to the right corner. Then, measure from the right corner to the left corner. Once you have these two measurements written down, move on to measuring the height. Measure from the top center of the jamb down to each side (left and right). Again, be sure to double-check all measurements for accuracy before moving on to selecting a replacement window.

By taking these extra measures when measuring for a replacement window, you can rest easy knowing that it will fit perfectly in its place. With this knowledge in hand, you’re now ready to find a beautiful new window for your home!

Measure Width and Height

Measure Shortest Measurement for Width and Height of Entire Window

It’s important to measure the width and height of your window opening accurately – even if it means taking extra measures. To make sure a replacement window will fit properly, you’ll need to measure the shortest measurement for both width and height of the entire window.

To do this, start by measuring from one side of the window opening to the other (width). Then, measure from top to bottom (height). This measurement should be taken at the narrowest part of each side. If you have an arch or angled tops in your window frame, be sure to adjust accordingly. Also, don’t forget to double-check all measurements for accuracy!

By taking accurate measurements of your window openings before investing in a replacement window, you can feel confident that it will fit perfectly in its place. With this knowledge in hand, you’re now ready to find a beautiful new window for your home!

Record Exact Measurements for Reference

When measuring your windows for replacement, it’s important to take exact measurements. This will ensure that your new windows fit perfectly in the window frame and look great. To do so, use a tape measure to measure the width of the opening from one side to the other, then measure the height from top to bottom. Make sure you record each measurement accurately and double-check them before finalizing anything. It’s also a good idea to write down these measurements for reference later on when you go shopping for replacement windows.

By taking accurate measurements of your windows and writing them down for reference, you can feel confident that your new windows will fit perfectly in their place without any problems. So don’t forget this simple but important step!

Step 3: Choose Replacement Window Type

Choosing the right type of replacement window for your home can be a daunting task. There are many different types of windows available, with various features and benefits that may or may not be suitable for your needs. The most common types include single hung, double-hung, casement, awning, sliding and bay windows. Single-hung windows open from the bottom only and are usually more affordable than other types; double-hung windows open from both top and bottom; casement windows open outward from the side; awning windows have hinges at the top which allow them to swing outwards; sliding windows are horizontally hinged which allows them to slide open; and bay windows consist of three or more sections connected together to form an arch or circle shape.

When choosing a replacement window type, consider factors such as size and style, ventilation needs, insulation requirements, durability and cost. For instance, if you need good air circulation in your home then you might want to go with an awning window or casement window. If insulation is important to you then double-paned glass windows would be your best bet. And if cost is an issue then you might opt for single-hung instead of double-hung since it’s usually cheaper. Ultimately, only you can decide which type of replacement window is best for your home so make sure you do plenty of research before making any final decisions!

Replacement windows come in many shapes, sizes, and styles to meet the needs of any homeowner. So take your time to research, compare prices, and find the perfect window for your home. And don’t forget, you have the option of either standard sizes or custom cut!

Consider Standard Sizes or Custom Cut Option

When it comes to replacing the windows in your home, you have a few options. You can choose either standard sizes that are already pre-measured and fit most windows, or you can go with the custom cut option. With this option, you are able to get windows that are specifically designed for your home’s exact measurements. This is often the more expensive route but it does ensure that your windows will fit perfectly.

Both standard and custom cut options come with their own pros and cons, so it’s important to consider all of your options before making a decision. Standard sizes offer convenience and affordability, while custom cuts offer precision sizing for more complex window shapes. Ultimately, the choice is up to you and what works best for your home. If budget is an issue then standard sizes might be the way to go; if aesthetics are important then custom cuts could be worth the extra cost.

Consider Standard Sizes or Custom Cut Option

Identify if Storm Windows Are Needed

If your windows are in need of replacement, it’s important to take a few things into consideration. One of the most important is whether or not you need storm windows in addition to the replacement windows. If your home is located in an area that experiences severe weather conditions, such as high winds, heavy rain, and extreme temperature changes, then storm windows may be necessary for providing extra protection against the elements. Storm windows typically cost more than regular replacement windows but can help protect your home from extensive damage caused by storms.

In order to determine whether or not storm windows are needed for your home, consider the type of climate you live in and the severity of weather conditions. You should also inspect your existing window frames and check for any signs of damage or wear and tear. In addition, you should speak with a local contractor who specializes in window installation to get their opinion on what type of window would be best for your home. Taking all these factors into consideration will help ensure that you have the right type of window installed in order to keep your home safe and comfortable.

Step 4: Install New Replacement Window

Once you have the correct measurements and have sourced the appropriate replacement window, it’s time to install it. Installing new windows can be a tricky process, so it’s important to take your time and follow all the steps carefully. First, you should remove the old window frames and any trim. Next, lightly sand down the frame of the replacement window to get rid of any sharp edges or splinters. Then apply a bead of silicone caulk around the perimeter of the frame to seal out moisture. Finally, use screws or nails to secure the window into place and add any necessary trim pieces for a finished look. If done correctly, installing a new replacement window can be an easy and rewarding task that will help enhance your home’s appearance and energy efficiency for years to come!

Installing a new replacement window can be a rewarding task that will add to the beauty and energy efficiency of your home! Now that you’ve got your new window in place, it’s time to select the appropriate vinyl replacement window to complete the job.

Install New Replacement Window


Selecting the right vinyl replacement window is an important step in finishing your window project. Vinyl replacement windows offer a variety of benefits, including improved energy efficiency and durability. When choosing a vinyl window for your home, consider the size, style, and frame type you need. You should also check out any warranties or guarantees that may be included with your purchase. Additionally, check to see if there are any local or state regulations that must be met before installation. Finally, take some time to research different brands to ensure you’re getting the best quality product for your money. With so many options available today, you’ll be sure to find the perfect vinyl replacement window for your needs!


Installing a new double-hung window is an easy and cost-effective way to update the look of your home. Before you begin, it’s important to follow the steps below to ensure that the window is properly installed and sealed.

  1. Measure your existing window opening to determine the size of replacement window you’ll need. This includes measuring both the width and height of the space in three places: at the top, middle, and bottom of the opening. Use these measurements to select a replacement window that fits perfectly in the space.
  2. Remove the old window by unscrewing all screws or nails on both sides of the frame and lifting it out carefully. Make sure to dispose of any glass safely.
  3. Place your new double-hung window into the opening from outside, making sure it is level and plumb before securing with nails or screws along all four sides of the frame.
  4. Add insulation around edges as needed for an airtight seal before caulking along all edges of frame from inside and outside for further weatherproofing protection.
  5. Check for proper operation by lifting up each sash—the top should lift easily and stay open without any sticking or binding issues, while bottom should lower smoothly without any resistance or excessive force needed to close it down again fully.

Once you’ve completed these steps, enjoy your new double-hung window! With regular maintenance, this new addition will provide years of beauty and energy efficiency to your home!


Installing exterior trim is a great way to give your home an updated look. This simple DIY job requires just a few basic tools and materials, such as a putty knife and tape measure. Here’s how to do it:

Start by measuring the length of the trim you will be installing. Once you have the measurements, mark them on the wall or siding with a pencil. Then, using a putty knife, carefully remove any old caulking or paint from that area.

Next, take your trim pieces and position them along the marked lines. Make sure they are even and use your tape measure to double-check that all sides are straight and level. Once in place, secure each piece with nails or glue as needed.

Finally, use caulk to fill in any gaps between pieces of trim and along the edges where they meet the wall or siding. Apply pressure to ensure that caulk is pressed firmly into place before it dries completely; then smooth out any excess material with the putty knife for a clean finish.

With these steps complete, your exterior trim should look like new! Just remember to check periodically for loose nails or other signs of wear so you can make sure your trim remains in good condition for years to come!


The fifth and final step in measuring and installing window trim is to check the fit and air leaks. Before you move on to any other projects, it’s important to make sure your trim fits correctly and there are no air gaps. To check for proper fit, open the window and inspect the trim from both inside and outside. Make sure it sits flush against the wall or siding and that there are no gaps around the edges. To check for air leaks, use a light-duty fan or hair dryer to blow across the area where your trim meets the window frame. If you feel any drafts, caulk may be needed to seal them up! Once everything looks good, your job is complete!

Now that your trim is installed, you can stand back and admire the finished product! With a few simple steps and some patience, you’ve successfully measured and installed window trim. But don’t forget to open and close the entire window several times to ensure that it fits properly before moving on to any other projects.


Opening and closing the entire window several times is an important step in ensuring your trim fits properly. It’s a simple yet effective way to make sure the trim is snug and secure against the window frame. To begin, open the window all the way. Check that there are no gaps between the trim and window frame, as well as any air leaks. Once you have inspected this, close the window fully. Then open it again and repeat this step until you have done it several times over. This helps to ensure that your trim is secure but also allows for proper expansion and contraction of the material throughout different temperatures. You may also want to check for proper fit from both inside and outside of the window. Doing this will ensure that your trim looks good from every angle!

Open and Close Entire Window Several Times to Check for Proper Fit

Inspect Areas Around Entire Window for Air Leaks

Inspecting the areas around the entire window for air leaks is an important step in ensuring your windows are properly sealed. Start by examining each of the four sides of the window, looking for any gaps or cracks between the window frame and trim. If you find any, you should then seal them with caulk. You can also use a candle to check for air drafts – if it flickers near any of the seams, this means there’s a leak that needs to be addressed. Once you have sealed up all of the gaps, open and close the window several times to check for proper fit and make sure everything is secure. Finally, inspect each of the seals around your windows from both inside and outside to make sure they are effective at blocking out drafts and moisture. With these steps complete, your windows should be air-tight and ready for whatever weather comes their way!


This guide has outlined a step-by-step process for measuring windows for replacement. It’s important to take accurate measurements and follow the instructions carefully in order to ensure that you purchase the right size window. Make sure to double check your measurements before ordering your replacement window. Once you have all of your materials, you’re ready to install your new window! Installing a new window can be an intimidating task, but it’s easier than you think. With patience and careful attention, you can make sure that your new window fits perfectly and looks great for years to come.

Frequently Asked Questions on Measuring and Installing Window Trim

Q: What type of measuring tape should I use to measure for a window replacement?

A: You should use a metal tape measure with metric and imperial measurements for the most accurate results

Q: How do I measure the window sill for a replacement window?

A: Measure the width of the window sill from one side to the other, at both its highest and lowest points. Note that these dimensions might be slightly different so make sure to record both measurements.

Q: How do I measure horizontal trim boards for a window replacement?

A: Measure the length of your horizontal trim board from left to right and make sure to record any gaps or protrusions along its edge.

Q: How do I measure vertical trim boards for a window replacement?

A: Measure the height of your vertical trim board from top to bottom, making sure to record any gaps or protrusions along its edge.

Q: When should I apply caulk when installing window trim?

A: Caulk should be applied around all edges and joints between the frame and wall, as well as around any seams in your trim boards . It should also be applied after the trim has been installed and before any painting.