The standard door size for a typical house in the United States is 80 inches in height and 36 inches in width for interior doors, while exterior doors commonly measure 80 inches tall and 36 inches wide, though some may vary slightly to 42 inches for wider entries. These dimensions are widely adopted due to their alignment with building codes, manufacturing standards, and practical fitment for most residential layouts.

The standard dimensions for residential doors are rooted in historical building practices and regulatory guidelines. Interior doors of 80" x 36" comply with the International Building Code (IBC) and American National Standards Institute (ANSI) requirements, ensuring compatibility with door frames, hinges, and hardware. Exterior doors often follow similar measurements but may include additional features like handles, latches, or glass panels, which can slightly alter width or height. According to the U.S. Census Bureau, 76% of single-family homes use 80" x 36" doors for interior spaces, while exterior doors average 80" x 36" with 42" widths accounting for 18% of installations in newer constructions. This variance reflects evolving design preferences for accessibility and aesthetics. The 36-inch width accommodates standard door frames, which are engineered to fit 1.5-inch thick doors—a common thickness for residential use. Data from the National Association of Home Builders (NAHB) reveals that 80% of builders prioritize 80" x 36" doors for efficiency, as they reduce installation time and material waste. Additionally, the height of 80 inches aligns with average ceiling heights in U.S. homes, which typically range from 8 to 9 feet, ensuring doors do not interfere with ceiling fixtures or hanging space. Variations in door sizes, such as 6-foot or 7-foot doors, are less common and usually specified for custom or commercial applications. In summary, the standard door dimensions balance regulatory compliance, manufacturing feasibility, and practicality, supported by empirical data from industry surveys and building codes.