Why are containers standard?
The external dimensions of shipping containers are set by ISO standards. This means the same container can travel on a ship, through a port, on a truck and on a train without ever being opened. Much of the speed of today's international trade rests on this standard.
There are two basic lengths: 20 feet and 40 feet. Ship capacity and port statistics are measured in TEU (twenty-foot equivalent units). A 20' container counts as 1 TEU and a 40' container as 2 TEU. A "24,000 TEU ship" is described in this unit.
Container codes
In practice, containers are referred to by abbreviations:
- DC / GP / DV: Dry Container, General Purpose. The standard dry cargo container.
- HC / HQ: High Cube. About 30 cm taller than standard.
- RF / RH: Reefer (refrigerated) / Reefer High Cube.
- OT: Open Top. No fixed roof; covered with a tarpaulin.
- FR: Flat Rack. A platform without side walls or roof.
Container explorer
Choose a type and the scale drawing, internal dimensions, door opening and weight capacity update. The proportions in the drawings are real, so you can compare a 20' and a 40' by eye.
Table view
| Type | Internal length | Internal width | Internal height | Door (W × H) | Volume | Tare | Max payload | Max gross |
|---|---|---|---|---|---|---|---|---|
| 20' Standard (Dry) | 5.90 m | 2.35 m | 2.39 m | 2.34 m × 2.29 m | 33.2 m³ | 2,300 kg | 30,200 kg | 32,500 kg |
| 40' Standard (Dry) | 12.03 m | 2.35 m | 2.40 m | 2.34 m × 2.29 m | 67.7 m³ | 3,700 kg | 28,800 kg | 32,500 kg |
| 40' High Cube | 12.03 m | 2.34 m | 2.70 m | 2.34 m × 2.60 m | 76.3 m³ | 3,850 kg | 28,650 kg | 32,500 kg |
| 45' High Cube | 13.56 m | 2.35 m | 2.70 m | 2.34 m × 2.60 m | 86.0 m³ | 4,700 kg | 27,800 kg | 32,500 kg |
| 20' Reefer | 5.45 m | 2.28 m | 2.27 m | 2.29 m × 2.26 m | 28.2 m³ | 2,905 kg | 27,575 kg | 30,480 kg |
| 40' Reefer High Cube | 11.58 m | 2.28 m | 2.53 m | 2.28 m × 2.54 m | 66.7 m³ | 4,300 kg | 29,700 kg | 34,000 kg |
| 20' Open Top | 5.90 m | 2.35 m | 2.38 m | 2.23 m × 2.28 m | 32.5 m³ | 2,450 kg | 30,050 kg | 32,500 kg |
| 40' Open Top | 12.03 m | 2.35 m | 2.38 m | 2.21 m × 2.29 m | 66.4 m³ | 3,850 kg | 26,630 kg | 30,480 kg |
| 20' Flat Rack | 5.61 m | 2.23 m | — | — | — | 2,740 kg | 31,260 kg | 34,000 kg |
| 40' Flat Rack | 11.65 m | 2.22 m | — | — | — | 5,950 kg | 44,050 kg | 50,000 kg |
Source: Hapag-Lloyd, Container Specification. The first variant of each type is shown; values vary by shipping line and year of manufacture. For flat racks, height and volume are determined by the cargo itself.
Volume or weight?
A container has two limits: volume (m³) and maximum payload (kg). Which one you reach first depends on the density of the cargo.
- Heavy cargo (marble, metal, chemicals) reaches the weight limit before filling the space. A 20' container is enough for these; a 40' gives no extra weight capacity.
- Light, bulky cargo (textiles, furniture, plastics) fills the space before reaching the weight limit. A 40' HC is the most efficient choice for these.
Note: a container's technical maximum weight is not the only limit on what you can load. Road weight limits are often more restrictive. Even if a 40' container is technically rated for well over 28 tonnes, the combined weight of tractor, chassis and container must stay within each country's legal limit. Check the limits in every country the cargo will cross before loading.
VGM: verified gross mass
Under the SOLAS (Safety of Life at Sea) Convention, the shipper must declare the verified gross mass (VGM) of every container to the carrier before it is loaded on the vessel. A container without a VGM is not loaded. The VGM is the total weight of the cargo, packaging, pallets, securing material and the container's tare.
Pallet loading calculator
How many pallets fit in a container? The calculator below works out the theoretical single-layer layout for the container and pallet type you choose, placing pallets in two orientations side by side to find the maximum.
Table view
| Container | Euro pallet (EUR/EPAL) (1.2 × 0.8 m) | Standard / industrial pallet (1.2 × 1 m) |
|---|---|---|
| 20' Standard (Dry) | 11 | 9 |
| 40' Standard (Dry) | 25 | 22 |
| 40' High Cube | 25 | 22 |
| 45' High Cube | 27 | 24 |
| 20' Reefer | 10 | 9 |
| 40' Reefer High Cube | 23 | 20 |
| 20' Open Top | 11 | 9 |
| 40' Open Top | 25 | 22 |
Theoretical single-layer layout, calculated from the internal floor dimensions with rows in two orientations. In practice there may be 1–2 fewer pallets.
In practice, door frames, pallet overhang and handling margins usually mean 1–2 fewer pallets. The common rule of thumb in the field is 23–24 Euro pallets and 20–21 standard pallets in a 40' container.
Test yourself
- You need to ship 22 tonnes of marble blocks. Would you suggest a 20' or a 40'? (Answer: A 20'. The cargo reaches the weight limit before the volume limit; a 40' gives no extra capacity and costs more in freight.)
- How many containers can 3 TEU be? (Answer: Three 20' containers, or one 40' and one 20'.)
- Which container can carry a machine that is 2.9 metres high? (Answer: An open top or a flat rack. The internal height of a 40' HC is 2.70 m.)