Whether you’re buying new windows for your home, renovating it, or buying a new build, understanding standard window sizes will help you make the most informed decision. Although many homes use common window dimensions, not all windows fit into these “standard” sizes.
Window type, size, and age of your home all play important roles when calculating dimensions. As you research what size you’re likely to find in your home, here’s what you need to know about standard window sizes, how to measure windows, and how much it costs to install them.
What are standard window sizes?
Most types of windows have standard sizes, so they can be mass produced and easily installed in any home. Manufacturers prefer windows in common size ranges because they can produce windows in large quantities, streamline production, and create products for both builders and homeowners (for later replacement).
Standard window sizes vary depending on the type of windows in your home. Below we break down each type of window and its standard dimensions.
Common standard window sizes by type
Single-hung and double-hung windows
- standard width:24, 28, 32, 40, 44, 48 inches
- standard height:36, 44, 48, 52, 54, 60, 62, or 72 inches
Single-hung windows have a fixed upper sash and a lower sash that moves to let in fresh air. In contrast, double-hung windows have both the top and bottom sashes open. These rectangular windows are a convenient choice for homeowners who want a functional, easy-to-maintain window that provides adequate ventilation.
casement window
- standard width: 16, 20, 24, 28, 32, 36, 40, 44, 48 inches
- standard height:24, 36, 48, 54, 60, 72, 84 inches
A casement window is a narrow window that, like a door, has hinges on the side and is opened by turning a crank from the side. These windows open very wide and are selected functionally for ventilation. Casement windows are locked with a latch hook on the inside, making it difficult for people to break in from the outside and providing excellent security.
double sliding window
- Standard width: 36, 48, 60, 72, or 84 inches
- Standard height: 24, 36, 48, or 60 inches
Sliding windows feature a movable window sash that slides horizontally and are ideal for areas where you can’t easily access the window and push it up, such as over a kitchen sink. These durable windows have two or three panels and offer unobstructed views and natural light.
picture window
- standard width:34, 36, 48, 60, 72 inches
- standard height:36, 48, 60 inches
Picture windows “frame” the outdoor view. These windows are rail-free and fixed, giving you a clear, unobstructed view of the outside world, making them ideal for living rooms and other rooms that need more natural light.
Awning and hopper windows
- standard width: 16, 20, 24, 28, 32, 36, 40, 44, 48 inches
- standard height:24, 36, 48, 54, 60, 72, 84 inches
One of the small window types on the market is an awning window (also known as a hopper window). It has a rectangular shape with a hinged top that opens like a sunshade. If you live in an area where it rains or snows frequently, awning windows can let fresh air in during inclement weather without forcing it into your home.
How to measure window size
Windows are measured in height and width. Manufacturers typically list window sizes as four-digit notations, such as 3030. This means the window is 3’0″ wide by 3’0″ high.
You can have your windows professionally measured, or you can measure them yourself at home using a tape measure. Standard window height is measured as width x height, so start with the width. As with any home measurement, you should run this process twice (ideally three times) to ensure you get the correct numbers.
How to check if a window is square
Before you can measure your window, you’ll first need to determine if it’s square (or has 90 degree corners). Measure with the tape measure to the top right corner of the window, then to the bottom right corner and write down the numbers. Repeat this process for the opposite corner and compare the numbers. Windows are square if they are within 1/4 inch of each other.
How to measure window width
You will need to measure the width of your window in three different places: at the top, in the middle, and at the bottom. Place the starting point of the tape measure inside the left window frame (this is the white part on the side of the window pane). Starting at the top, extend the measuring tape to the edge of the right frame. Record that number. Repeat measurements to the center of the window, then to the bottom.
There should be three numbers. The smallest number is the width.
How to measure window height
You will need to measure the height of your window in three places: left, right, and center. Start your tape measure at the bottom of the window (but not the trim or any part of it that sticks out from the base of the wall the window sits on). Hold it straight up to the top of the window and write down the measurements. Repeat the same steps for the center and right side of the window.
The smallest of these three measurements will be the window height.
How to roughly measure the window opening
Measure again the same way you measured the width and height, but measure the opening where the contractor will install the window. Typically, the rough dimensions of the opening are 1/2 inch larger than the vertical and horizontal dimensions of the window.
Recommended rough opening sizes vary by window type, so have a professional double-check your measurements. Even the slightest mistake can result in poorly installed windows that leak air and increase your utility bills.
Finally, don’t rely on old plans when determining window dimensions. Many areas require building permits to replace or widen windows, or to add new windows where none existed before. However, if work was previously carried out without permission, it will not be noted on the old plans of the house.
Do standard window sizes vary by room?
Although window sizes do not necessarily vary from room to room, you may find that certain types of windows are more common in certain spaces based on the window’s function and appearance. For example, your bedroom should have large windows that allow you to escape in case of a fire or emergency. The required size varies by location, but is usually at least 20 inches wide by 24 inches high.
In most regions, no specific windows are required in the kitchen. Nevertheless, it is practical to have windows in this area for ventilation and natural light, so casement windows, double-hung windows, garden windows and sliding windows are common. Similarly, bathrooms typically don’t require specific windows per code, but ventilation is important. Bathroom windows are often at least 2 feet wide and 3 feet high. Popular choices include casement windows, sliding windows, casement windows, and awning windows.
As a rule of thumb, these standard window sizes also depend on the age of your home.
When standard window sizes don’t apply
Some homes and windows may require custom sizing due to unique window shapes, features, age, etc. Older or historic homes often have window shapes and sizes that were popular at the time but are no longer standard. This is a distinctive part of your home that deserves to be respected with a custom replacement to maintain the home’s appearance and energy efficiency.
“A common misconception is that homes have ‘standard’ window sizes that can be easily replaced,” says Yuri Pearl, owner of Nealon Insulation. “However, we find that many older homes have custom or slightly irregular openings, so forcing a standard size can lead to air leaks and trim issues. Accurate measurements and a good fit are more important than finding a ‘standard’ size.” ”
Special windows, such as bay windows or bow windows, or windows with unusual shapes, such as arched windows or geometric windows, are visually interesting but are not standard sizes. Instead, these windows are customized to fit the outside of your home. Another consideration is structural changes during home renovations.
How window size affects cost and installation
Window size affects cost and installation in a number of ways. First, larger windows require more materials and are more expensive.
Custom windows have a big impact on the cost of a renovation project because you’ll pay a premium to have them manufactured to your home’s specifications. You should also consider the time it takes for the manufacturer to create your custom windows.
When it comes to installation, custom windows or larger windows will cost more. Some of these windows require creating and framing new rough openings, which is extra work for the contractor. Other locations, such as bay and bow windows, require additional home reconstruction during the process, increasing the labor hours and skills required for the project.
conclusion
When looking for replacement windows, standard window sizes are a good starting point. However, accurate measurements and recommendations from a professional window installer are important to avoid ordering the wrong window size or experiencing installation issues.
Take the time to carefully measure your windows, shop around, and then check the size with a reputable window installer or contractor.
FAQ
Is there really a standard window size?
No, there is actually no standard window size, but there is a range of standard window sizes that are built into many homes. You can measure the size of your windows at home, but if you are considering replacing your windows, it is safer to have a professional measure and confirm the size of your windows.
Is the replacement window smaller than the original opening?
Replacement windows are usually slightly smaller than the original opening to ensure a secure fit. Full frame replacement windows are an option and can improve the energy efficiency and appearance of your home. However, full frame replacements are expensive.
Does your older home have non-standard window sizes?
Older homes often feature non-standard window sizes because they are unpopular in today’s market and feature non-standard window sizes and shapes. Another consideration is that before modern technology, people relied on windows for natural light and airflow, so older homes usually have large windows.
