According to International Residential Code (IRC), an egress window must satisfy four criteria:
Minimum width of opening: 20 in.
Minimum height of opening: 24 in.
Minimum net clear opening: 5.7 sq. ft. (5.0 sq. ft. for ground floor).
Maximum sill height above floor: 44 in.
The window must have a minimum net clear opening of 5.7 sq. ft. Net clear opening refers to the actual free and clear space
that exists when the window is open. It is not the rough opening size or the glass panel size, but the actual opening a person
can crawl through.
The window opening must be operational from the inside without keys or tools. Bars, grilles and grates may be installed over
windows but must be operational without tools or keys and still allow the minimum clear opening.