What are the dimensions of standard exterior doors?

Standard exterior doors are typically designed to fit common structural openings in residential and commercial buildings. The dimensions of 3 feet wide by 6 feet 8 inches tall (3'0" x 6'8") represent the most commonly used size for exterior doors. This size is widely accepted in the building industry as an optimal balance between accessibility and structural integrity.

Having a standard width of 3 feet allows for easy passage, making it accommodating for various needs, including moving furniture in and out of the house. The height of 6 feet 8 inches is also ideal for most people, providing ample vertical space without being overly cumbersome.

The other dimensions listed do not correspond to standard sizes. For example, a narrower width of 2 feet 6 inches is often used for interior doors, while the option with a height of 6 feet 4 inches is not common for exterior doors, as it may restrict access. A height of 7 feet and width of 3 feet 6 inches is less frequently used and often designated for custom applications or specific architectural styles. Thus, option C accurately reflects the widely recognized standard for exterior doors in most building contexts.