Standard Replacement Window Size Charts

Published April 26, 2022
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Lake Washington Windows

Making sense of standard window sizes can be complicated, to say the least. Each window style has its own set of standards, and the location of a manufacturer may affect those standards. The sheer number of styles and sizes is enough to overwhelm anyone. However, Lake Washington Windows and Doors is here to help make sense of all the confusion. In this article, we’ll explain the business of standard window sizes. We hope it will help to bring some clarity to anyone exploring the world of replacement windows. Please don’t hesitate to contact us with any questions that come up along the way. Our sales team will be happy to provide any answers needed.

Are there standard replacement window sizes?

The short answer is yes. There are standard window sizes established for replacement windows. However, these standard window sizes vary for all types of windows. Each style has a minimum and maximum standard window width and a minimum and maximum standard window height. Between those, each window type has a range of sizes in standard increments. For example, standard double-hung window sizes vary in width from a minimum of 24 inches to a maximum of 48 inches wide, while they have a minimum height of 36 inches and a maximum of 72 inches with incremental heights of 44, 52, 54, and 62 inches.

How are windows measured?

When measuring home windows, we follow a simple four-step process. The first step is to ensure the window frame is square, meaning each of the four corners sits at equal 90-degree angles. The following step measures the window width at the top, bottom, and center. After that, we measure the window height at the far left, center, and far right. It’s important to note that window measurements are always recorded: width x height.

The next step is to measure the window’s depth from inside the exterior trim to inside the interior trim. Window depths are relatively consistent and only tend to vary in mobile and modular homes. We take the final step to round all measurements to the nearest ⅛ inch. Those are the essential measurements needed before selecting a replacement window. For an in-depth explanation, learn how to measure windows for replacement.

Understanding rough opening size

Before a window or door is installed, a frame is built that consists of a header across the top, a sill plate across the bottom, and two vertical trimmers on the left and right. The rough opening size is a term that refers to the dimensions of the frame in which a window or door will be placed. The rough opening size will be larger than the window dimensions of the unit installed. Once a window is installed, the additional space between the window unit and the rough opening frame is filled with insulation materials.

Window size notation explained

Standard window sizes include a four-digit notation representing the window style’s width and height measured from the rough opening. The first two digits represent the window width and the second two represent the window height, measured in feet. A double-hung window placed in a rough opening that measures 48 inches wide by 72 inches tall (4 feet x 6 feet) would have the notation 4060. A window measuring 48 inches wide by 62 inches tall (4 feet x 5 feet 2 inches) would have the notation 4052. However, the actual window dimensions will be about half an inch shorter in each direction.

Double Hung Windows

Double-hung windows, also referred to as double-sash windows, have two operable upper and lower sashes. The most commonly selected style is those with sashes that open vertically. However, there are double-hung window syles with sashes that open on hinges, both inwardly and outwardly. In addition to providing additional ventilation compared to single-hung windows, double-hung windows offer a level of safety for families with young children since the upper sash can be opened to provide ventilation while remaining out of reach.

  • Min width: 24 inches
  • Max width: 48 inches
  • Min height: 36 inches
  • Max height: 72 inches
  • Found in: Bedroom, kitchen, and hallways
24″ 28″ 32″ 40″ 44″ 48″
36″ 2030 2430 2830 3430 3830 4030
44″ 2038 2438 2838 3438 3838 4038
48″ 2040 2440 2840 3440 3840 4040
52″ 2044 2444 2844 3444 3844 4044
54″ 2046 2446 2846 3446 3846 4046
60″ 2050 2450 2850 3450 3850 4050
62″ 2052 2452 2852 3452 3852 4052
72″ 2060 2460 2860 3460 3860 4060

Single Hung Windows

Single-hung windows, also referred to as single-sash windows are one the most common types of windows available. Single-hung windows have a fixed upper sash with an operable lower sash that slides vertically to provide ventilation. Single-hung windows are generally less expensive and easier to install than double-hung windows while providing better energy efficiency due to their fixed upper sash.

  • Min width: 24 inches
  • Max width: 48 inches
  • Min height: 36 inches
  • Max height: 72 inches
  • Found in: Bedroom, kitchen, and hallways
24″ 28″ 32″ 40″ 44″ 48″
36″ 2030 2430 2830 3430 3830 4030
44″ 2038 2438 2838 3438 3838 4038
48″ 2040 2440 2840 3440 3840 4040
52″ 2044 2444 2844 3444 3844 4044
54″ 2046 2446 2846 3446 3846 4046
60″ 2050 2450 2850 3450 3850 4050
62″ 2052 2452 2852 3452 3852 4052
72″ 2060 2460 2860 3460 3860 4060

Picture Windows

Picture windows are fixed windows generally made of a single pane of glass that provides a view of a home’s surroundings. They are designed to provide an unobstructed picturesque view, hence the name picture windows. These windows can be ordered in various sizes ranging from small to very large. Because the glass is fixed, picture windows don’t provide ventilation. However, the fixed pane does make them a great choice for energy efficiency.

  • Min width: 24 inches
  • Max width: 96 inches
  • Min height: 24 inches
  • Max height: 96 inches
  • Found in: Living room, kitchen, above gardens, viewpoints
24″ 36″ 48″ 60″ 72″ 96″
24″ 2020 3020 4020 5020 6020 8020
36″ 2030 3030 4030 5030 6030 8030
48″ 2040 3040 4040 5040 6040 8040
52″ 2044 3044 4044 5044 6044 8044
60″ 2050 3050 4050 5050 6050 8050
62″ 2052 3052 4052 5052 6052 8052
72″ 2060 3060 4060 5060 6060 8060
96″ 2080 3080 4080 5080 6080 8080

Casement Windows

Casement windows were one of the earliest designs of opening windows invented. Modern casement windows operate with an easy-to-use hand-crank at the bottom of the window opening. They are usually hung with hinges on the vertical side, allowing them to open outward to provide excellent ventilation. French casement windows, known as French windows, consist of two sashes that meet in the middle, extending inwardly. Modern casement windows include gaskets around all sides, allowing them to be more energy-efficient than horizontal sliding windows while providing greater ventilation.

  • Min width: 18 inches
  • Max width: 36 inches
  • Min height: 18 inches
  • Max height: 72 inches
  • Found in: Kitchen, bedroom, bathroom, living room
18″ 20″ 24″ 30″ 36″
18″ 1616 1816 2016 2616 3016
20″ 1618 1818 2018 2618 3018
24″ 1620 1820 2020 2620 3020
30″ 1626 1826 2026 2626 3026
36″ 1630 1830 2030 2630 3030
48″ 1640 1840 2040 2640 3040
60′ 1650 1850 2050 2650 3050
72″ 1660 1860 2060 2660 3060

Horizontal Sliding Windows

Horizontal-sliding windows are another prevalent window style, perhaps the most common. This style consists of two or three sashes mounted next to each other horizontally. They can be single sliders or double sliders, with one or two sashes opening past the others by sliding horizontally along a track at the bottom of the window. Horizontal-sliding windows are versatile and relatively cost-effective. However, they are considered slightly less energy efficient than hinged windows.

  • Min width: 36 inches
  • Max width: 84 inches
  • Min height: 24 inches
  • Max height: 60 inches
  • Found in: Bedrooms, bathrooms, basements, kitchens

Window Size Chart with Notations

36″ 48″ 60″ 72″ 84″
24″ 3020 4020 5020 6020 7020
36″ 3030 4030 5030 6030 7030
48″ 3040 4040 5040 6040 7040
60″ 3050 4050 5050 6050 7050

Awning Windows

Awning windows are essentially casement windows hinged on the top to open vertically and outward from the bottom of the frame. Modern awning windows open with a hand-crank at the bottom of the window. They provide good ventilation and typically seal well to ensure energy efficiency. Because they open vertically and outward, they provide better protection from light rain than other windows. At the same time, their size and orientation allow them to be placed in higher and smaller spaces than other window styles.

  • Min width: 18 inches
  • Max width: 72 inches
  • Min height: 18 inches
  • Max height: 72 inches
  • Found in: Bedroom, basement, bathroom

Window Size Chart with Notations

18″ 20″ 24″ 36″ 48″ 60″ 72″
18″ 1616 1816 2016 2616 3016 4016 5016 6016
20″ 1618 1818 2018 2618 3018 4018 5018 6018
24″ 1620 1820 2020 2620 3020 4020 5020 6020
30″ 1626 1826 2026 2626 3026 4026 5026 6026
36″ 1630 1830 2030 2630 3030 4030 5030 6030
48″ 1640 1840 2040 2640 3040 4040 5040 6040
60″ 1650 1850 2050 2650 3050 4050 5050 6050
72″ 1660 1860 2060 2660 3060 4060 5060 6060

Bay Windows

A bay window, also referred to as bow windows, consists of several angled panels that protrude outward from a wall of a home to form an alcove that provides a wide peripheral view. Typically, the angled window panels of a bay window are either casement, single, or double-hung windows so they can be opened to provide ventilation. In contrast, the main window will be a picture window that provides an unobstructed view. Below the bay window sill, within the alcove, a bench can be placed to provide a seating area.

  • Min width: 42 inches
  • Max width: 126 inches
  • Min height: 36 inches
  • Max height: 72 inches
  • Found in: Living room, dining room, bedroom

Bay and Bow Window Options

Bay or Bow Window Projection Angle Total Window “Lites” Total Angled “Lites” % of Glass Surface Per Total Main “Lites” % of Glass Surface Per
Bay 25° 3 2 1/4 1 1/2
Bay 35° 3 2 1/4 1 1/2
Bay 45° 3 2 1/4 1 1/2
Bow 25° 3 2 1/3 1 1/3
Bow 35° 3 2 1/3 1 1/3
Bow 45° 3 2 1/3 1 1/3
Bow 10° 4 4 1/4 0 0
Bow 15° 4 4 1/4 0 0
Bow 10° 5 5 1/5 0 0
Bow 15° 5 5 1/5 0 0
Bow 10° 6 6 1/6 0 0
Bow 15° 6 6 1/6 0 0

Common questions about window sizes

Do window sizes include the frame?

Yes, window sizes include the frame  unless otherwise noted, or you are looking only to purchase the replacement glass for a window. When measuring vinyl and aluminum window sizes, it’s essential to measure the entire unit – glass, frame, and window sash. On the other hand, older wood-framed window measurements go by the size of the glass. This is because vinyl and aluminum windows come as an entire unit, while when replacing windows made of wood, the glass can be replaced without replacing the rest of the unit.

Do window sizes vary by the manufacturer?

Window sizes do vary depending on the manufacturer. These differences are often minor and can change by product line. Likely, these differences will not affect the desired standard size of the window. Selecting a 2’x2’ window may turn out to be 23-⅝” x 23-⅝” from one manufacturer or 23-⅞” x 23-⅞” from another.

Are builder grade windows and replacement windows sized differently?

Yes. Builder-grade or new construction windows are larger because they include a nail fin used to secure the window to the rough opening frame. Replacement windows, or retrofit windows, can be installed without removing the existing frame. Your vendor and or salesperson will be able to order the correct size window by telling them whether it is a replacement window or a new construction window.

Does the window material affect the window size?

Materials will affect particular aspects of the window size and how big the window can be. For example, many wood-clad windows can be made in larger sizes than fiberglass windows, or aluminum windows can have a thinner frame than wood-clad. However, the evolution of windows is ongoing, and the most standard window sizes will remain the same despite the material.

What are custom window sizes?

Custom windows can be ordered to fit a rough opening that doesn’t match standard window sizes. Most window manufacturers will be able to produce different windows that match your home’s unique specifications. However, custom window sizes will be more expensive than standard window sizes that are prefabricated and ready for sale.

What size is an egress window?

The size of an egress window depends on the specific building codes of your home’s area. Because egress windows are installed as a means for emergency escape, their measurements must meet specific requirements to allow inhabitants to climb through the window. The International Building Code advises that egress windows measure at least 5.7 square feet, 20 inches wide by 24 inches high.

Why are there so many different window sizes?

There are so many different window sizes because the design of every home is unique. One of the significant design aspects that give homes their character is the design of their windows. If window sizes were limited, homes would lose an essential part of their character.

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