The minimum size required for an egress window is a width of opening of 20 inches and a height of opening of 24 inches. Also, an egress window requires a minimum net clear opening of 5.7 feet or five feet if it is on the ground floor and a maximum sill height of 44 inches above the floor.
The net clear opening is the minimum amount of space a person has to crawl through. People must be able to open the window without any tools or keys in case of emergency. These windows are required for every room with a sleeping space and for basements with areas people live in.