What Is a TEU?

What Is a TEU?

TEU stands for Twenty-foot Equivalent Unit. It is the container shipping industry's universal unit of measurement. One TEU represents the capacity of a standard 20-foot ISO container: 20 ft (6.1 m) long, 8 ft (2.44 m) wide, and 8 ft 6 in (2.59 m) high. That gives you roughly 33.2 cubic metres of internal volume and a maximum gross weight of approximately 24 tonnes.

The TEU standard emerged in the 1960s when containerization was being formalized. At that point, the 20-foot box was the default. When 40-foot containers arrived later, the industry kept the TEU as its base unit and simply counted a 40-footer as 2 TEU. It is not perfectly precise, a 40-foot container holds 67.7 m³, slightly more than twice a 20-foot unit's 33.2 m³, but the convention has stuck for six decades and shows no sign of changing.

How TEU Measurement Works

The conversion is dead simple: 20-foot box = 1 TEU, 40-foot box = 2 TEU. That rule applies regardless of container type. A refrigerated unit, an open-top, a flat rack, a tank container, they all count the same way based on length. A 45-foot container is typically counted as 2.25 TEU.

But here is something most people do not think about: container type changes real capacity even when TEU count stays the same. A 40-foot high-cube container is 9 ft 6 in tall instead of the standard 8 ft 6 in, that extra foot adds roughly 13% more internal volume (76.4 m³ vs 67.7 m³). Yet for vessel capacity purposes, it still counts as 2 TEU. The same ship can carry "more cargo" at the same TEU count if more of its slots contain high-cubes.

At the port level, TEU throughput is measured four ways: laden imports, laden exports, empty imports, and empty exports. Then there are transshipment moves, containers that are discharged from one vessel and loaded onto another without ever leaving the terminal. This is the number that inflates some ports' TEU counts significantly. Singapore and Port Klang, for instance, derive over 80% of their container volumes from transshipment.

Modern terminals track TEU throughput in real time: OCR cameras on quay cranes capture container numbers, RFID tags track boxes through the yard, and the terminal operating system (TOS) logs every lift, gate move, and stack position.

The largest vessels currently in service: MSC Irina at 24,346 TEU, followed by OOCL Spain (24,188 TEU), ONE Innovation (24,136 TEU), MSC Tessa (24,116 TEU), and Ever Alot (24,004 TEU). All are roughly 400 metres long and 61 metres in beam, about the maximum dimensions that current port and canal infrastructure can accommodate. The global cellular container fleet stood at approximately 33.7 million TEU as of January 2026, with MSC commanding roughly 7.05 million TEU (21.3% global share), followed by Maersk and CMA CGM. The orderbook at end-2024 reached a record 12.98 million TEU.

Why TEU Matters in Shipping

TEU is not just an abstract statistic. It directly determines what shippers pay. Terminal handling charges, wharfage, port dues, all quoted per TEU. Demurrage and detention fees accrue per TEU per day. When a carrier publishes a freight rate, it is typically per container by TEU size.

Port authorities use TEU forecasts to justify capital spending. A single new berth capable of handling 1 million TEU per year costs USD 300 to 500 million. That bet only makes sense if the TEU growth projections hold. Shipping lines deploy vessels and allocate slots based on TEU-mile data, total TEU carried multiplied by distance. Trade economists watch TEU growth as a leading indicator: in developing economies, container throughput typically grows at 1.5x to 2x the rate of GDP.

Want a practical gotcha? Empty container repositioning generates TEU throughput numbers for a port but contributes zero revenue to the cargo owner. A port can show growing TEU volumes while the underlying trade is flat or even declining, simply because more empties are passing through. When someone cites a port's TEU growth, ask whether they are counting laden TEU only or total TEU including empties and transshipment. The difference can be enormous.

Technology and TEU Management

AI-based container recognition has reached the point where OCR systems at terminal gates can capture container numbers, ISO type codes, and door directions with over 99% accuracy in real time. These systems feed data into the terminal's TOS and, increasingly, into digital twin models that simulate container flows and predict yard congestion before it happens.

Automated stowage planning software calculates the optimal placement of 20-, 40-, and 45-foot containers across a vessel's bay positions. It accounts for weight distribution, port rotation sequence, hazardous cargo segregation, and the stacking constraints of different container types. A poorly planned stowage plan can waste hundreds of TEU slots across a single voyage.

Frequently Asked Questions

How many TEU can the largest container ship carry?

As of mid-2026, MSC Irina holds the record at 24,346 TEU. Built by Yangzijiang Shipbuilding and launched in March 2023, it is 399.9 metres long with a 61.3-metre beam. Four other ships top 24,000 TEU: OOCL Spain (24,188), ONE Innovation (24,136), MSC Tessa (24,116), and Ever Alot (24,004). All of these ultra-large vessels primarily serve the Asia-Europe trade lane, where ports have invested in the deep water and long-reach cranes needed to handle them.

Why is a 40-foot container counted as 2 TEU instead of 1?

The TEU standard was set in the 1960s when the 20-foot container was the only size in widespread use. When 40-foot containers came along, the industry adopted the convention of counting each as 2 TEU rather than redefining the base unit. The convention has persisted even though a 40-foot container (67.7 m³ internal) provides slightly more than double the internal volume of a 20-foot unit (33.2 m³). The shared end-wall space of two 20-footers accounts for the difference.

Related tool: Compare container ship drafts and TEU capacities in our Vessel Draft Comparison table (51 real vessels).

Related Terms

• FCL vs LCL, The two fundamental container shipping modes, both measured in TEU for vessel planning purposes.
• Container Terminal, A specialized port facility where containers are loaded, discharged, and stored, with throughput measured in TEU.
• FEU (Forty-foot Equivalent Unit), An alternative unit equal to one 40-foot container or 2 TEU. Common in North American domestic logistics.