Maritime Glossary
Twenty-Foot Equivalent Unit
Also known as: TEU
TEU stands for twenty-foot equivalent unit, the standard measure of container capacity. One TEU is the volume of a standard twenty-foot shipping container, giving the industry a common way to count boxes of different lengths.
Full Definition
The twenty-foot equivalent unit exists because containers come in more than one length but the industry needs a single number to compare them. A standard twenty-foot container is one TEU. A forty-foot container (by far the most common box in service today) counts as two TEU, and a forty-five-foot high-cube unit is normally still counted as two TEU. Counting in TEU lets a terminal, a shipping line or a statistician add up a mixed stack of boxes into one comparable figure.
A container ship's capacity is quoted in TEU, and the scale is enormous. Small feeder vessels that serve regional ports carry a few hundred to a couple of thousand TEU, while the largest ultra-large container vessels on the main east–west trades carry more than 24,000 TEU on a single voyage. Ports and terminals report their annual throughput in TEU as the headline measure of how busy they are, and carriers are ranked by the total TEU capacity of their fleets.
It is important to remember that TEU measures slots, not weight. A slot filled with dense cargo such as machinery and a slot filled with light cargo such as packaging both count as one TEU, even though their weights differ greatly. This is why a container ship is constrained by two separate limits at once (its TEU capacity and its deadweight tonnage) and why stowage planners must balance the load so the ship is neither physically full while still light, nor down to its marks while still holding empty slots. The TEU, together with its cousin the FEU (forty-foot equivalent unit), remains the fundamental accounting unit of the container trade.