A twenty-foot equivalent unit (TEU) is the standard unit for counting container capacity: one 20’ ISO container equals 1 TEU. You’ll see it in vessel sizes, port rankings, and trade statistics. The catch is what it leaves out. A TEU counts container slots on a ship by length, and says nothing about how much cargo volume or weight is inside the box.
TEU meaning: how each container type converts
The reference box is the ISO 668 20’ container. It is nominally 20 feet long, but its actual external length is 6.058 m (19'10.5"), with a width of 2.438 m (8 ft). Everything else is counted by how many of those lengths it takes up.
That makes TEU a length-based count. The question it answers is how many 20-foot container slots on the vessel a box occupies. Height is ignored, and so are volume and weight. A 40’ container takes two slots, so it counts as 2 TEU, which is also 1 forty-foot equivalent unit (FEU).
| Container | External length | TEU | Notes |
|---|---|---|---|
| 20’ standard | 6.06 m | 1 | — |
| 20’ half-height | 6.06 m | 1 | Same length, lower height |
| 40’ standard | 12.19 m | 2 | 1 FEU |
| 40’ high cube | 12.19 m | 2 | 1 FEU; height doesn’t change the count |
| 45’ HC | 13.72 m | 2.25 (often counted as 2) | — |
| 53’ (North American domestic) | 16.15 m | About 2.65 | Not an ISO ocean size |
A few rows need a closer look:
- 40’ high cube. At 2.896 m tall externally, versus 2.591 m for a standard box, a high cube is still 2 TEU. The same logic runs the other way: a half-height container, at roughly half the usual height, is still counted by its length, so a 20’ half-height is 1 TEU.
- 45ft high cube. Divide 45 by 20 and you get 2.25 TEU. In slot planning and commercial practice, though, a 45’ is often counted as 2 TEU, because it rides in a 40’ cell with its ends overhanging. When a statistic includes 45’ boxes, check which convention it uses.
- 53’ domestic. These are used for domestic rail and road moves in North America and aren’t an ISO ocean size. The 2.65 figure is the nominal ratio (53 ÷ 20), not a measured one.
What a TEU measures, and what it doesn’t
Because a TEU only counts slot length, three things follow. Each one is a common source of planning mistakes.
Height doesn’t count. A 40’ high cube holds 76.3 m³ against 67.7 m³ for a 40’ standard container: 8.6 m³ more, or about 13%. Both are 2 TEU. Two fleets with the same TEU total can have quite different usable volume, depending on how many high cubes each one runs.
Weight doesn’t count. A ship’s TEU capacity assumes an average container weight. Vessel specs often quote capacity at a homogeneous load: every box the same weight, with the weight evenly distributed, commonly about 14 t per TEU. If a large share of the containers on board are heavy, the vessel hits its deadweight tonnage (DWT) or stability limit first, and slots go empty. Draft restrictions at the ports on the route set another ceiling. The nominal TEU number is a maximum, not what the ship actually carries on a given voyage.
Cargo doesn’t count. A 20’ box of ping-pong balls is 1 TEU. So is a 20’ box of steel coils. For planning your own shipment, work in CBM and kilograms, not TEU.
Where you’ll see TEU figures
Vessel size. TEU capacity is the usual way to describe a container ship. The largest ultra large container vessels (ULCVs) in service today are rated at just over 24,000 TEU; MSC IRINA, delivered in 2023, is rated at 24,346 TEU. As a rough guide, feeder vessels run about 300–3,000 TEU, and ships built to the old Panamax limits about 4,000–5,000 TEU. Those class ranges are approximate, and they vary by source.
Port throughput and trade statistics. Ports rank themselves by annual TEU handled. Shanghai, the world’s busiest container port for 16 years running since 2010, handled 55.06 million TEU in 2025, up 6.9% year on year. Of that, 7.91 million TEU was international transshipment, up 10.6%. Port throughput is not the same as trade volume. It counts every container lifted on or off a ship, loaded or empty, and a transshipment box is counted again each time it crosses the quay.
Freight rates. Rate benchmarks often use FEU rather than TEU. The Drewry World Container Index, for one, is published per 40ft container. Other indices, and some trade lanes, may use a different unit, so confirm the unit before you compare two figures. For your own shipment, a full container load (FCL) quote is priced per container type (20’, 40’, or 40’ high cube), not per TEU.
From TEU to actual cargo: CBM and kg
To get from a TEU figure to something you can load, go back to the containers themselves.
- 1 TEU (20’ standard): 33.2 m³ nominal volume, and a payload of about 28 t (28,200 kg in the CargoSum calculator; carrier specs list 28,130 kg and 28,330 kg).
- 1 FEU: 67.7 m³ for a 40’ standard, or 76.3 m³ for a 40’ high cube. Payload is similar to a 20’ (28,800 kg for the 40’ standard and 28,620 kg for the high cube in the calculator). Depending on the carrier and the box’s maximum gross weight rating, a 40’ can even carry less payload than a 20’.
In practice you won’t fill the nominal volume. With real boxes, a common planning figure for a 20’ is about 25–28 CBM, roughly 75–85% of the nominal 33.2 m³. That’s an industry rule of thumb, not a guarantee. The guide to how much CBM fits in a container explains where the space goes. For internal dimensions, door openings, and tare weight by container type, see container dimensions.
To decide whether your shipment needs 1 TEU (a 20’) or 1 FEU (a 40’), enter your box list in the container loading calculator, then run it once with a 20’ selected and once with a 40’ and compare the results. It works from your actual box dimensions instead of an average fill rate.
What is a TEU?
TEU stands for twenty-foot equivalent unit. One standard 20’ ISO container equals 1 TEU, and the unit is used to express container capacity: how many boxes a vessel can carry, how many a port handles in a year, and how much container trade moves on a route. It counts container slots by length, not the volume or weight of the cargo inside.
Is a 40ft container 1 TEU or 2 TEU?
A 40’ container is 2 TEU, also called 1 FEU (forty-foot equivalent unit). A 40’ high cube is also 2 TEU. The extra height of a high cube (2.896 m external vs. 2.591 m for a standard box) doesn’t change the count, because TEU is based on length only.
What is an FEU?
FEU stands for forty-foot equivalent unit: one 40’ container, equal to 2 TEU. It shows up most often in freight rate benchmarks. The Drewry World Container Index, for example, is published per 40ft container. Other indices and trade lanes may use a different unit, so check the unit before comparing figures.
How many TEU is a 45ft container?
By length, a 45’ container works out to 2.25 TEU (45 ÷ 20). In vessel slot planning and commercial practice, though, a 45ft high cube is often counted as 2 TEU, because it sits in a 40’ cell with its ends overhanging. When you quote statistics that include 45’ boxes, check which convention the source used.
How much cargo fits in 1 TEU?
A 20’ standard container has a nominal volume of 33.2 m³ and a payload of about 28 t (28,200 kg in the CargoSum calculator). With real boxes, a common planning figure is about 25–28 CBM, or roughly 75–85% of nominal. That range is an industry rule of thumb, not a guarantee; the actual figure depends on box sizes and how the load is built.
How many TEU does the largest container ship carry?
The largest container ships in service are rated at just over 24,000 TEU; MSC IRINA, delivered in 2023, is rated at 24,346 TEU. That is a nominal slot count. When a large share of the containers are heavy, the ship reaches its deadweight or stability limits before every slot is filled, so the real load is usually lower.
Is TEU a unit of volume or weight?
Neither. A TEU is a count of 20-foot container slots. A 20’ box full of ping-pong balls and one holding steel coils are both 1 TEU. The external volume of a 20’ container ranges from about 19 to 43 m³ depending on height (half-height to high cube), which is why cargo planning uses CBM and kilograms instead.