What are Standard Window Sizes?

Article Summary: Standard window sizes refer to the most common measurement ranges for specific window styles, which can vary depending on the manufacturer. For instance, standard double-hung windows typically measure between 24 and 48 inches wide and 36 to 72 inches high, whereas sliding windows generally range from 36 to 84 inches wide. Because exact dimensions are critical and manufacturers often deduct a half-inch for installation clearance, industry professionals highly recommend using a tape measure to determine your exact width and height rather than relying on generic size assumptions.

If you're looking to replace a window, you can just hop online and order a small, medium, or large, right?

Well, unfortunately, no.

Windows aren't like coffee. There's no tall, grande, or venti to choose from. You may have an idea of what the average size of a window looks like in your home, but when it comes to actual measurements, you'll quickly find that a "standard" size is a rare find. From modern homes to historical houses, windows vary in size, style, and even material.

So where do you start?

Despite the variety, there are some rules you can follow when it comes to finding the right window size for your home. Join us as we take a look at standard sizes, standard materials, and how you can sound like a window pro on your next trip to the hardware store.

What is a standard window size?

A standard window size refers to the most common window measurements. If you've ever worked with lumber, you've probably heard someone talk about a 2x4—that's a standard size for wood.

Windows, however, are a little more complicated.

Is there a standard window size?

Yes and no. Windows come in all shapes and sizes, including custom, so there aren't just a few standard sizes to choose from. That said, each style of window tends to have its own standard sizes across most home designs. If you know your style, you can usually narrow down the options.

However, even those options can have surprise variations. Measurements are measurements, but different brands and manufacturers might have different definitions of "standard." A "standard" double-hung window from one company might have slightly different measurements than the company down the street.

When in doubt, it's always best to determine window size with a tape measure, rather than an assumption.

Check out our in-depth guide for a full breakdown of how to measure your windows.

How do you read a window size?

When measuring and ordering windows, you need to speak the same language as your manufacturer. So when talking about window size, keep in mind that you'll always measure your width and then your height.

Window size is written down as width (feet and inches) and height (feet and inches). These two numbers are combined into one four-digit number with the first two digits representing the width and the second two digits representing the height.

For example, if you needed a window with a 3'8" width and a 2'2" height, the window size would read 3822. If you went to a manufacturer and asked for a 3822 window, they'd know what size you meant. (That's for those of us in the U.S. who measure in feet and inches…metric is a whole different ball game!)

When measuring a window for a replacement, measure the rough opening rather than the existing window itself. Remove the trim if needed, then measure the opening from the inside of one side jamb to the other at the top, middle, and bottom. Record the smallest width in inches. 

Next, measure from the sill to the top of the opening at the left, center, and right, and record the smallest height. Measure the depth as well to confirm the replacement window will fit the frame.

Take each measurement to the nearest 1/8 inch, and write the width before the height. For example, an opening that is 36 inches wide and 48 inches high may require a slightly smaller replacement window. 

Manufacturers typically leave about 1/4 inch of clearance on each side, so the actual window can measure roughly 1/2 inch smaller than the opening. Always compare your measurements with the manufacturer's sizing guide before ordering.

What size are standard windows?

Though window sizes vary, there is a standard range of sizes for different types of windows.

For homeowners who use metric measurements, 1 inch equals 25.4 millimeters (mm), and 1 foot equals 304.8 mm. For example, a common 24" x 36" window measures about 610 x 914 mm, while a 36" x 48" window measures about 914 x 1,219 mm. Use these conversions as a guide, but always measure the rough opening in inches or millimeters before ordering, since manufacturers may list window sizes differently.

What is the standard bedroom window size?

Most bedroom windows are either double- or single-hung windows unless you invest in a large picture window style. If you have another style, these sizes don't apply. But for the majority of homeowners, your bedroom windows should fall between these dimensions:

• Standard Bedroom Window Width: 24" - 34"
• Standard Bedroom Window Height:  36" - 62"

If your bedroom has a bay window or other more elaborate setup, you might not be dealing with a standard size. In that case, you'll want to measure the custom dimensions yourself.

What are standard casement window sizes?

Casement windows open towards the exterior of a home on a hinge and are one of the most popular choices for airflow. However, they do tend to run on the smaller side overall compared to double-hung or sliding windows. Most casement windows fall between these dimensions:

• Standard Casement Window Width: 14" - 36" or 1.2' - 3'
• Standard Casement Window Height: 30" - 78" or 2.5' - 6.5'

A note from the pros: Casement windows tend to have less leeway in manufacturing dimensions because the leverage required to operate their opening mechanism stops working effectively after you reach 36" x 78" (or 3678).

What are standard double-hung window sizes?

Double-hung windows are the most common type of window in modern home architecture. They're made of two window sashes that move up and down to open and close via a latch system. Because of their popularity, they come in nearly any size you need, but the most common double-hung sizes fall between these dimensions:

• Standard Double-hung Window Width: 24" - 48" or 2' - 4'
• Standard Double-hung Window Height: 36" - 72" or 3' - 6'

These standard double-hung window sizes also provide a useful guide for single-hung windows. A single-hung window has one movable sash, while the other sash remains fixed. Common single-hung window sizes range from 24 to 48 inches wide and 36 to 72 inches high, although exact dimensions vary by manufacturer and room. 

These standard window sizes apply throughout the home, not only in bedrooms, so they cover a wider range than the bedroom window measurements listed above. Always measure the rough opening in inches before ordering a replacement.

What are standard sliding window sizes?

Sliding windows are almost identical to double-hung windows, but they slide open horizontally. They still have two sashes, but they open left-to-right instead of top-to-bottom. Unlike double-hung windows, sliding windows almost always have a larger width than height. The most common sliding window sizes come in the following dimensions:

• Standard Sliding Window Width: 36" - 84" or 3' - 7'.
• Standard Sliding Window Height: 24" - 60" or 2' - 5'.

Like double-hung windows, sliding windows are commonly found in all types of rooms.

What are standard picture window sizes?

Picture windows are typically quite large, as their main appeal is their ability to provide uninterrupted light and amazing views. However, because picture windows are constructed from a single massive sheet of glass, installation can be more expensive due to increased risk. The standard ranges for picture window sizes are:

• Standard Picture Window Width: 24" - 96" or 2' - 8'
• Standard Picture Window Height: 24" - 62" or 2' - 5.2'

What are standard bay window sizes?

Bay windows, like picture windows, tend to run on the larger side. However, unlike picture windows, bay windows can be installed to open and close. That means that when you're looking at bay window sizing, you're actually looking at the sizing of three different window panels—frequently double-hung, single-hung, or casement. The size ranges below refer to the entire width and height of the bay window, not the individual components:

Standard Bay Window Width: 42" - 126" or 3.5' - 10.5'.

Standard Bay Window Height: 36" - 78" or 3' - 6.5'.

What are other important window measurements?

Not all window measurements are about the entire window. Let's take a look at a few standard measurements for specific window parts. Keep in mind that, just like the full-window sizes, these are all averages; each window part should still always be measured before ordering a replacement.

Standard window frame thickness

Window frame thickness comes down to two key factors: the material of the frame and the location of the home. Homes in areas with extreme weather will normally have thicker walls and need a thicker frame to accommodate the space—although you can choose a thinner frame for aesthetics. Additionally, the thickness depends on your frame material, though all float around 0.5 inches:

• Standard Wooden Window Frame Thickness: 10mm - 20mm
• Standard Aluminum Window Frame Thickness: 16mm-26mm
• Standard uPVC Window Frame Thickness: 20mm-28mm.

There aren't any strict regulations when it comes to window frame thickness, but if you know you're up against the elements every year, the thicker you can go, the better.

Window glass size

Window glass size aligns with the size of your frame and the style of your window. Window glass thickness, however, is up to you. No matter what type of glass you choose, most window glass comes in two basic thickness measurements:

• Single strength: 3/64" thick
• Double strength: ⅛" thick

The overall window thickness also depends on the number of panes you choose for your window. For instance, a single-paned, single-strength window would only be 3/64" thick. However, a triple-paned, double-strength window would have three panes of glass measuring at ⅛" thick plus the space in between the panes. Space in between your double- or triple-paned glass varies, but can be as wide as an inch to accommodate gas fillers to improve insulation.

In general, when looking at window thickness, more glass means

Are window screens standard sizes?

Yes. Window screens, unlike windows, come in standard sizes because they don't have to fit the entire window. The three most common standard screen sizes are:

1. 18" x 14"
2. 18" x 18"
3. 20" x 20"

That said, you can get a screen in any size you need for any window that opens and closes. You simply may have to pay more for a custom size—especially if it's not a square or rectangle.

Ensure you're ordering correctly sized windows by consulting the experts

Not sure what window size you need? No problem. When it comes to home window replacements, Window Nation is here to answer all your questions. We make ordering and installation easy—no matter your home renovation savvy. With a focus on quality, efficiency, and long-lasting expert installation, we're happy to work with you to complete the window project of your dreams. We can even help you design custom-sized vinyl windows for that long-awaited remodel.

Contact Window Nation today for a free quote.