The ship dimensions, such as the ship breadth, depend on the number of containers placed abreast on deck and in the holds. Thus, one extra container box abreast in a given ship design involves an increased ship breadth of about 2.8 meters. The average loaded container weighs about 10-12 tons but, of course, this may vary, so the modern container vessels are dimensioned for 12-14 dwt per TEU.
Containership capacity is normally expressed in Twenty-foot Equivalent Units (TEU), which is defined as the number of 20' x 8' x 8'6" containers it can carry; or, similarly, in Forty-foot Equivalent Units. Containerships vary considerably in size. Some of those serving major ports have capacities exceeding 5,000 TEU. Some recently built for feeder service (i.e., serving small outports from a major port) have capacities of 400 TEU or less.
