Egress Window Cost : Egress Window Size Calculator

Egress Window Size Calculator

Our egress window size calculator (located below and additional egress window calculator ) provides hundreds of different project price quotes based on different openings and sizes. We've included the four most popular styles of egress windows, including casements, horizontal sliders, single hungs and double hungs. Casement windows are the most popular option here because nearly the entire IGU opens, which allows for a smaller window that still satisfies the egress size requirement. This is the reason we pre-selected medium casement in question 1 of our egress window size calculator.

If you are considering putting in an egress window in your home, my suggestion is to collect at least 4 local bids -- especially if your project is in the challenging to very difficult category. You're going to find a huge range of price quotes (in my experience), which is good, because with some time and patience, you can sit down and compare them side-by-side, and hopefully find a quality local company and negotiate a competitive price for your project. Thanks for taking a look at our egress window size calculator and enjoying playing around with different options and selections.

Bill - Site Editor - Updated In September, 2026

Egress Windows Sizing Calculator

If you have project questions on the cost to add egress window, ask our site editor and get the answers you need! Email your questions to Bill

Net Clear Opening

Net clearing opening is the cross sectional area of a window. In the case of an emeregency exit, this crosssectional space must by at least 5.7 square feet. This amount of space is what the building code requires for an adult (including a fireman with a breathing apparatus) to enter or exit the window in case of an emergency. Code also requires a minimum height and width. However, the height and width are almost always going to be met when the net clear opening requirement is 5.7 sq. ft or greater.

Measuring the net clear opening is easily done. With the sash open, measure the window from the inner edge of the frame across and then measure from the inner edge of the frame down to get the width and height of the clear opening. Then, multiply these numbers and divide by 144 to get the square footage.

Egress Window Size Chart

Our egress window size chart below provides general information on window sizes. However, it's always best to speak with several contractors or installation companies to find out if the requirements for your city and county.

Casement Egress Windows

Casements must meet the following minimum window sizes for code. 20" wide & 24" tall, as well as meet the building code requirement of 5.7 square feet of net clear opening. Casements can be the smallest windows (compared to other window styles) and still satisfy the egress size requirement due to the fact that roughly 90% of the window area opens. Compare this with sliders and hung windows where this percentage is closer t0 40%.

For more on how net clear opening affects the size of window, see our page on egress window size requirements.

Small Casement: 20"W x 24"H
Medium Casement: 28"W x 40"H
Large Casement: 40"W x 72"H

More On Egress Casements

Slider Egress Windows

Sliders must meet the following minimum window sizes for code. 4' wide & 4' tall, as well as meet the building code requirement of 5.7 square feet of net clear opening.

Small Slider: 48"W x 48"H
Medium Slider: 60"W x 60"H
Large Slider: 72"W x 72"H

More On Sliding Window Options

Egress Window Size Calculator: Double Hungs

Double hungs must meet the following minimum window sizes for code. 3' wide & 5' tall, as well as meet the building code requirement of 5.7 square feet of net clear opening.

Small Double Hung: 36"W x 60"H
Medium Double Hung: 48"W x 64"H
Large Double Hung: 60"W x 72"H

More On Double Hung Windows

Egress Window Size Calculator: Single Hungs

Single hungs must meet the following minimum window sizes for code. 3' wide & 5' tall, as well as meet the building code requirement of 5.7 square feet of net clear opening.

Small Single Hung: 36"W x 60"H
Medium Single Hung: 48"W x 64"H
Large Single Hung: 60"W x 72"H

Single Hung Options

Replacement Window Cost

Egress Window Size Notes

The minimum 20-inch width and 24-inch height requirements are intended to ensure that an emergency escape and rescue opening is large enough for a person to pass through and for emergency personnel to gain access. For example, even if a window technically provides enough total square footage, an opening that is only 14 to 16 inches high may still be too small to qualify as an egress opening.

The same principle applies to unusually narrow windows. A tall double-hung window might provide enough opening height and total square footage, but it must still meet the minimum clear-opening width. Meeting the square-foot requirement alone is not enough — an egress window must satisfy the applicable minimum width, height, and net clear-opening requirements.

The standard minimum net clear opening is generally 5.7 square feet. However, qualifying grade-floor emergency escape and rescue openings may have a reduced minimum net clear opening of 5.0 square feet.

It's also important not to confuse this 5.0-square-foot exception with the separate 44-inch sill-height requirement. The 44-inch measurement generally refers to the maximum height of the bottom of the clear opening above the finished interior floor. Whether a window qualifies for the 5.0-square-foot grade-floor exception depends on its classification under the applicable building code, rather than simply whether the window is within 44 inches of the exterior ground.

Because local building codes and adopted IRC editions can vary, homeowners should always verify the specific egress requirements with their local building department before ordering replacement windows.

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Related Topics: Egress Windows Code

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