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Bay Windows Sizes (Measurements & Dimensions Guide)

Here’s our bay windows sizes guide including standard & different bay window dimensions and how to measure & calculate the area for a bay window.
Bay windows sizesA great way to add extra dimension and depth to any room is by installing bay windows over regular windows to give the illusion that the space is much bigger than it actually is. Another hack to utilize that space is adding a lounge area for reading or even a breakfast nook for your early morning coffee and newspaper in your kitchen. 

Generally, bay windows are angled on two sides and will protrude from your house at a 30 or 45-degree angle. They come in many sizes, so any size you might need for your home will be available, from the smallest to the most oversized bay windows.

Standard Bay Window Sizes

Standard Bay window sizesA bay window is essentially made up of combining three windows manufactured to make one large window unit. These three windows are connected by mullion posts, and the middle window is usually a casement window

There are no fixed standard sizes for a bay window, but the most common sizes utilized by many households will range from 3 feet and 6 inches to 10 feet and 6 inches, or about 107 to 320 centimeters for the width.

In contrast, their heights will vary from the standard 3 feet to 6 feet and 6 inches, or approximately 91 to 198 centimeters. 

This option is also the most cost-effective since it can easily fit in a standard-size window if renovations are done to your home. 

45 Degree Bay Window Dimensions

45 degree bay window dimensionsThe size of a bay window protruding at a 45-degree angle will have many available sizes depending on the window configuration you are looking to get. Typically, only the center window will have a variety of venting configurations that you can get from the regular stationary center window to picture windows for more oversized bay windows. 

A regular 45-degree bay window with a venting or stationary center will have a width ranging from 45 3/4 to 91 1/4 inches or 116 to 232 centimeters.

In contrast, the heights will usually be somewhere on or between 26 1/8 to 73 7/8 inches or 66 to 188 centimeters, with a projection of 14 3/16 to 27 1/2 inches or about 36 to 70 centimeters. 

At the same time, a 45-degree bay window with a fixed picture window center will have a width of 66 to 127 1/4 inches or 168 to 323 centimeters, a height of 38 to 61 7/8 inches or 97 to 157 centimeters, and a projection of 14 7/8 to 27 1/2 inches or 38 to 70 centimeters. 

Most standard bay windows have a 45-degree outside angle compared to a garden window which features a 90-degree outside angle.

What Is The Normal Angle Of A Bay Window?

The Bay window is an umbrella representation for all window constructions that protrude no matter the height. Since a bay window will protrude out at an angle on the outside of a home, it is essential to know what angle is normal to guide our search, and ultimately, our choices. 

The most common bay windows will have a normal inside angle of about 90 or 135 degrees. Once that degree is at 120, it will be called an Oriel Bay Window, which curves less than it is angled.

How Deep Should A Bay Window Be?

Bay windows sizesThe depth of a bay window will be dependent on the angle it will protrude. There are usually two window angles available for a bay window, and those are the bay windows that will protrude at a 30-degree and 45-degree tilt. 

A 30-degree bay window will usually have a depth of 12 to 14 inches or about 30 to 36 centimeters. In contrast, a 45-degree bay window will have a depth of 16 to 22 inches or 41 to 56 centimeters. 

How Far Out Does A Bay Window Protrude?

Knowing how far a bay window will stick out of the house is vital. Still, one of them is safety since we don’t want anyone bumping their heads accidentally in a game of hide and seek or if they are watering the plants directly underneath each bay window. 

How far it will stick out will depend on the depth. However, most outward projections can be as short as 12 inches to several feet.

If you plan on a design that can hold shelving and decor items such as a kitchen bay window, or a custom window seat you will need to carefully consider spacing and structural integrity.

What Is The Smallest Bay Window?

Small bay window with fixed picture window stone wall claddingThe smallest bay window is the standard bay window with a width of 3 feet and 6 inches or about 107 centimeters and a height of 3 feet or about 36 inches. This size will fit the most common window spacing and offer the 180-view that more oversized bay windows will offer. 

How Do You Calculate The Area Of A Bay Window?

Some might hear “calculating the area of a bay window” and think about how hard it will be, but the good news is, it is easier than it sounds and will only require precise measuring and basic math. Here is how. 

The first thing you need to do is add the individual areas of a window bay’s floor areas. A window bay will usually consist of a square and a triangle, so assuming that the square is about 12 feet and the triangle is 6 feet, it will give you the square footage of the bay windows at 18 feet. 

How Do You Measure For A Bay Window?

The first thing to measure is the size of each window panel. There are three measures in a bay window, and it will usually involve measuring the width and the height for each of them separately. 

Next, measure the depth from the front of the second window pane down to the middle of the central window pane. Last is measuring the total width by calculating the distance from left to right. 

What Size Curtains Do I Need For A Bay Window?

Big bay window with large picture window large curtainA safe rule of thumb in figuring out the curtain you need for your bay windows is doubling the width measurements of the window itself. 

For example, if you have a window that is 40 inches wide, you will need a curtain double that size in width at 80 inches to make sure that there are no gaps and that the windows are covered completely when curtains are utilized. 

For more related content visit our guide to the types of bow windows here.