An egress window must have a net clear opening of 5.7 square feet. Net clear opening refers to the free space created when the window is open or the actual space through which a person can crawl.
The opening height and width of an egress window must be at least 24 and 20 inches respectively. However, a window that was the minimum height and width would not qualify as an egress window because the square footage would total only 3.33 square feet. Additionally, the bottom of the clear opening must be no higher than 44 inches off the floor. Egress requirements apply to at least one window in the basement and all bedrooms below the fourth story. Windows on the ground floor of the dwelling must have only a 5-square-foot net clear opening. Almost all window manufacturers designate in their catalogues which windows meet egress requirements.