According to ISO standards, there are five common standard length shipping containers: 20-ft (6.1 m), 40-ft (12.2 m), 45-ft (13.7 m), 48-ft (14.6 m), and 53-ft (16.2 m). United States domestic standard containers are generally 48 ft (15 m) and 53-ft (rail and truck). Container capacity is often expressed in twenty foot equivalent units or (TEU)). An equivalent unit is a measure of containerized cargo capacity equal to one standard 20 ft (length) × 8 ft (width) container. As this is an approximate measure, the height of the box is not considered, for instance the 9 ft 6 in (2.9 m) High cube and the 4-ft 3-in (1.3 m) half height 20 ft (6.1 m) containers are also called one TEU.