All shipping containers are a created at a 'standard' size (in order to stack them during shipping).
20ft units externally measure: 20ft (6.1 meters) long, 8 ft (2.44 meters) wide, and 8ft 6 inches (2.59 meters) high.
The internal dimensions of the containers may vary slightly depending on the construction method used.
The sides of a container are in nearly all cases, corrugated. The depth of the corrugation is usually 1 inch (25mm), which means that 2 inches (50mm) 1 inch per side is lost from the external width dimension, giving an internal width of 7 feet 10 inches (2.38 meters).
The back (blank end) of the container is also corrugated and the doors are around 2 inches (50mm) thick meaning that approximately 3 inches (75mm) is lost from the length, giving an internal length of 19 feet 9 inches (6.02 meters).
The main reduction from external to internal dimensions is with height. The floor of a standard container has an underside clearance of approximately 6 inches (150mm) and the floor has a thickness of 27mm (1.1 inches). As the roof is corrugated another 1 inch (25mm) is lost resulting in an internal dimension of around 8 inches less than external – 7ft 10 inches (2.39 meters), though this can vary slightly depending on the flooring material used.
Through the door height is further reduced because of the steel top rail above the door which is a part of the structural integrity of the container, this is 4 inches (100mm) thus reducing the entrance height of a standard 20ft container to 7ft 6ins (2.28 meters), though this can vary slightly either way.
20ft External Dimensions
(Length Width Height)
20' x 8' x 8'6" (Imperial)
6.1m x 2.44m x 2.59m (Metric)
20ft Internal Dimensions
(Length Width Height)
19'9" x 7'10" x 7'10" (Imperial)
6.02m x 2.38m x 2.39m (Metric)