Looking to Learn about Standard Window Sizes & Dimensions? Use this professional guide.

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What Are Standard Window Sizes?

When you’re shopping for windows, you’ll probably notice that most of them are available in a few consistent dimensions. These windows are designed to fit into the most common rough opening sizes in homes around the country. They won’t work for every window replacement, but it makes sense to produce windows that will work for most people. To avoid paying a premium on custom windows, stick to these standard window sizes when possible.

Standard Window Sizes of double hung windows

How to Understand Measurements of Standard Window Sizes

When you go to the local home improvement store, you’ll see windows listed in whole number dimensions. Just because you see a window designed to fit a whole number measurement doesn’t mean that the window has exact whole number dimensions. For example, a window marked to fit a 44″ x 44″ opening will actually measure around 43 ½” x 43 ½”. That’s because the manufacturer removes a half inch from each of the dimensions so the window can be installed with ease.

What Are Standard Window Sizes & Notations?

Windows are given a special size notation that’s simple to understand. Once you understand this size notation, you’ll be able to choose your windows much more quickly and confidently. Here we go!

Size notation is split into four digits, the first two are for width and the second two are for height.

To give you an example of size notation, a 2426 window would be 2’4″ wide and 2’6″ tall. The first digit of the notation standards for feet and the second stands for inches. If you want a window that is 44″ wide or 3’8″ you would want a 38 window. If you want a window that’s 44″ wide and 60″ tall you would want a 3850 with the 50 signifying 5’0″ or 60″ overall. There is a bit of a learning curve, but once you understand window size notation you’ll be able to quickly select the right window for your home.

A 2020 Window

The 2020 window is a very common type within most standard window sizes. It measures 24 x 24 inches or two feet by two feet in size with one of the most common rough openings. Since these dimensions are so common in new homes and many older homes as well, there are windows known as 2020 windows designed to fit this space. The windows are 2′ 2″ x 2′ 2″ in size or 24″ x 24″ minus the half inch allowance from both the height and width of the window.

When you go to the store and you see a 2020 window, it’s actually 23 ½” x 23 ½” in size. It is made for the very common 24″ x 24″ rough opening and is readily available.

A 3838 Window

Another common window opening is 44″ x 44″. The windows fit for these openings are known as 3838 windows. They are given this name because they are 3’8″ x 3’8″ or 44″ x 44″ in size, minus the ½” allowance. That means a 3838 window is actually 43 ½” x 43 ½” in size.

A window on a white house

The Benefit of Standard Rough Openings

It’s simple to order windows in custom dimensions, but it’s also quite expensive compared to the standard windows that you’ll find on the shelves. That’s because they aren’t produced in large quantities—and in some cases, they actually have to be crafted specifically for you.

If your home has standard rough openings, you can choose from a variety of pre-made windows that can be put right into those openings.

If you don’t have standard openings, you can adjust the dimensions of your existing openings to make them standard. Generally, it’s easiest to reduce the size of your opening by adding wood to the window frame, but the frame can also be expanded with new headers to meet any size that you want. If you’re tired of relying on custom windows, simply adjust the openings to a more standard size and start shopping the available standard options. If you choose to go this route, though, be aware that it’s best to have the help of a professional.

What are Standard Rough Opening Sizes?

Standard rough opening sizes are different depending on the type of window. If you’re looking for standard windows to fit your rough opening, it might be worth it to consider a different type of window.

Double Hung Windows Standard Sizes

Standard Window Sizes of a Double hung window
Double hung windows are the most popular type of window in the United States. They come in a wide variety of standard sizes to choose from. Here are the most common widths:

Widths

  • 24″
  • 28″
  • 32″
  • 40″
  • 44″
  • 48″

Heights

  • 36″
  • 44″
  • 48″
  • 52″
  • 54″
  • 60″
  • 62″
  • 72″

Picture Windows Standard Sizes

Standard Window Sizes Picture
Picture windows are designed for architectural appeal and for allowing more light into a home. Most of them don’t open, but they’re built in a wide variety of sizes, including:

Widths

  • 24″
  • 36″
  • 48″
  • 60″
  • 72″
  • 96″

Heights

  • 12″
  • 18″
  • 24″
  • 36″
  • 48″
  • 52″
  • 60″
  • 62″
  • 72″
  • 96″

If you’re considering picture windows, you have a lot of options. If you have an opening that fits one of these dimensions, you can likely install picture windows without needing to custom order them.

Single Slider Windows Standard Sizes

Standard Window Sizes Single Slider
Single slider windows are less common, but they are offered by a wide variety of manufacturers and come in standard sizes.

Widths

  • 36″
  • 48″
  • 60″
  • 72″
  • 84″

Heights

  • 24″
  • 36″
  • 48″
  • 60″

Slider windows are wider than they are tall. If your window dimensions fit into this range, you can pick up an off-the-shelf slider and have it installed without special ordering.

Obtaining Windows Quickly

Custom windows have to be created or shipped from a specialized location. On the other hand, standard windows are already produced and sitting in warehouses and on shelves around the country. That’s why if you need to have your windows installed as quickly as possible—say you have a broken window that needs immediate replacement—standard windows are the way to go.

A contractor measures out the space for a skylight

Ordering Custom Window Sizes

If you can’t locate standard sized windows to fit into the rough openings of your home, you have two options. The first is to adjust the size of your rough opening to accommodate a standard window. This is often the best option if the adjustments aren’t difficult.

The second is to order custom windows through a supplier like Lowes, Home Depot, or a local window company. You’ll give your window measurements to an associate and decide what type of windows you need, as well as what frame material and glass you want. The supplier will help you figure out which companies can complete the order for you. You’ll then select the company, pay for the windows and wait for your order to be filled.

After the order is in, you’ll wait several weeks for the windows to be manufactured and shipped. You can either have the windows delivered to your location or go and pick them up. You’ll be responsible for finding the professionals to install them for you unless it was included in your purchase agreement.

Generally when you are purchasing windows for your home you’ll be looking at standard windows, especially when you are just getting replacement windows. Standard sizes are very common in new construction or homes built within the last 30 years.

 

Older homes are especially well known for needing custom sized windows. This is because they were built before windows were being produced in mass quantities, so their windows often have odd dimensions that don’t fit standard window sizes. Dealing with custom windows is more time consuming, and there are more decisions to be made. You’ll also spend a great deal more money than you would with standard windows. But the benefit is that custom windows offer you more feature options, so they’re tailored specifically for your home.

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