TEU (Twenty-Foot Equivalent Unit)

TEU (Twenty-Foot Equivalent Unit) is the standard unit for measuring container capacity and container traffic. One TEU is the space taken by one standard 20-foot shipping container, about 6.1 metres long and 2.44 metres wide. Shipping lines use it to state how much a vessel can carry, ports use it to report how many containers they handle, and analysts use it to track the volume of international trade.

TEU is a measure of volume and slots, not of weight or value. A 40-foot container counts as two TEU and is sometimes measured separately as an FEU (forty-foot equivalent unit), the unit in which ocean freight rates are usually quoted. TEU figures are often compared across trade lanes, where the busier direction is the headhaul and the return is the backhaul.

Picture a car park where every bay fits one small car. A van takes two bays, so the car park's size is described in bays, whatever mix of vehicles happens to park there. TEU does the same job for ships, trains and container yards: the 20-foot box is the "bay", and bigger boxes are counted as multiples of it.

This lets anyone compare very different operations with one number. A ship "rated at 20,000 TEU" has room for roughly that many small boxes, or half as many long ones. A port that "handled 40 million TEU" in a year moved that many box-equivalents across its quays. The number says nothing about what is inside the boxes or how heavy they are, which is why it sits beside weight and value figures rather than replacing them.

Containers are built to standard ISO dimensions, so their TEU value follows from their length. A count of boxes converts to TEU as:

• $N_{20}$ is the number of 20-foot containers, each counted as one TEU.
• $N_{40}$ is the number of 40-foot containers, including taller "high cube" boxes, each counted as two TEU.
• $N_{45}$ is the number of 45-foot containers, which many ports count as 2.25 TEU; some count them as two, so reports should state their convention.

For example, a vessel discharging 1{,}200 twenty-foot boxes, 3{,}000 forty-foot boxes and 100 forty-five-foot boxes moves:

The same 4,300 boxes would be 3,712.5 FEU, since one FEU equals two TEU. Empty containers count in port throughput as well as full ones.

Modern container shipping is usually dated to 26 April 1956, when Malcom McLean's converted tanker Ideal X carried 58 containers from Newark to Houston. Early boxes came in many lengths, which made it hard to share cranes, ships and trucks. International standards for container dimensions were adopted from the late 1960s, and the 20-foot box became the common reference size, giving the industry the TEU as a shared unit.

Ship sizes have grown steadily since, helped by economies of scale in fuel and crew per box. The largest container ships in service, such as Evergreen's Ever Alot and MSC's Irina class, delivered from 2022 and 2023, are rated at about 24,000 TEU. In September 2025 Ocean Network Express reported a record of 22,233 TEU actually loaded on a single ship, ONE Innovation.

Port throughput in TEU is a widely watched indicator of trade activity. Shanghai, the world's busiest container port, handled about 51.5 million TEU in 2024, the first port to pass 50 million in a year. Because box volumes respond quickly to demand, analysts read TEU trends alongside gross domestic product (GDP) and trade deficit data to gauge the economy.

In a single shipment the unit is more practical. The bill of lading, or its digital form, the electronic bill of lading (eBL), lists container numbers and sizes, which banks check against the commercial invoice when paying under a letter of credit. Freight is priced per container, so the agreed Incoterms decide whether buyer or seller pays it, and port demurrage is charged per container per day. Lenders in trade finance and compliance teams watching for trade-based money laundering compare declared goods with the number and type of boxes shipped.

A ship's nominal TEU capacity assumes every slot is filled with light containers; weight limits usually stop that happening. Carriers therefore also quote capacity at an average of 14 tonnes per TEU, which is lower than the headline figure. Shipbuilders and databases can also differ on a vessel's rating, as with Ever Alot, listed at 23,888 TEU by some databases and 24,004 TEU by its builder. TEU also ignores refrigerated capacity, the cargo's value and whether boxes are full or empty, so volume growth can hide flat or falling trade in value terms.

• UNCTAD: Review of Maritime Transport
• Faisal Khan: Empty Shipping Container Economics