Shipping container types and dimensions: how to choose
The most common ocean containers are the 20' and 40' standard and the 40' High Cube, while special cargo moves in refrigerated (reefer), open top, flat rack and tank containers. ISO 668 fixes the external dimensions of general purpose containers, but internal dimensions, tare and payload vary between series and carriers. The right choice depends on the weight, volume, height and temperature needs of the goods.
By Hiram Trade Editorial Desk
- Published
5 min read
Dimensions under ISO 668
ISO 668 sets the external dimensions plus minimum internal dimensions and minimum door openings. The figures below are taken from the Hapag-Lloyd container specification, which reproduces the standard.
| Parameter | 20' | 40' | 40' High Cube |
|---|---|---|---|
| External length | 6,058 mm | 12,192 mm | 12,192 mm |
| External width | 2,438 mm | 2,438 mm | 2,438 mm |
| External height | 2,591 mm (8'6") | 2,591 mm (8'6") | 2,896 mm (9'6") |
| Minimum internal length | 5,898 mm | 12,029 mm | 12,029 mm |
| Minimum internal width | 2,350 mm | 2,350 mm | 2,350 mm |
| Minimum internal height | 2,350 mm | 2,350 mm | 2,667 mm |
| Minimum door opening (W x H) | 2,337 x 2,261 mm | 2,337 x 2,261 mm | 2,337 x 2,565 mm |
Typical general purpose container figures
Real containers are usually slightly larger than the minimum. Sample values from the Hapag-Lloyd fleet (individual series differ):
| Parameter | 20' standard | 40' standard | 40' High Cube |
|---|---|---|---|
| Inside (L x W x H) | 5,900 x 2,352 x 2,393 mm | 12,032 x 2,352 x 2,395 mm | 12,032 x 2,352 x 2,700 mm |
| Door opening (W x H) | 2,340 x 2,292 mm | 2,340 x 2,292 mm | 2,340 x 2,597 mm |
| Max. gross weight | 32,500 kg | 32,500 kg | 32,500 kg |
| Tare | approx. 2,300 kg | approx. 3,700 kg | approx. 3,900 kg |
| Max. payload | approx. 30,200 kg | approx. 28,800 kg | approx. 28,600 kg |
| Capacity | approx. 33.2 m³ | approx. 67.7 m³ | approx. 76.3 m³ |
Two practical conclusions. First, a 40' does not carry twice the tonnage of a 20': payloads are similar, only the volume differs. Heavy bagged goods such as sugar, fertiliser or tiles usually travel in 20', light and bulky goods in 40' or 40' HC. Second, the carrier's maximum gross weight is not the same as the road or rail limit in the destination country; Hapag-Lloyd explicitly refers customers to local offices for those limits. Check them before planning to use the full payload.
Refrigerated container (reefer)
A reefer has its own refrigeration unit and holds a set temperature; it needs power at the terminal and on board. A sample Hapag-Lloyd 40' High Cube reefer has an interior of about 11.58-11.60 m length, 2.28-2.29 m width and 2.53-2.55 m height, a maximum stowage height marked by a red line (about 2.42 m), gross weight up to 34,000 kg and payload of about 29,500 kg. The carrier states a temperature range from -40°C to +30°C.
What matters with reefers:
- the set point and ventilation settings stated in the shipping instructions, not only in an email,
- respecting the maximum load line, because cargo above it blocks air circulation,
- pre-cooling the goods; the container maintains temperature but is not designed to pull down warm cargo quickly.
Open top
An open top container has a removable tarpaulin instead of a roof. It is used for cargo too tall for standard doors or cargo that must be crane-loaded from above, such as machinery or stone blocks. A sample 40' open top has an interior of about 12.03 x 2.35 m and payload of roughly 26,600-28,500 kg depending on the series. Cargo protruding beyond the container outline is out of gauge and needs separate carrier approval and pricing.
Flat rack
A flat rack is a platform with end walls and no side walls or roof. It carries heavy and oversized cargo: steel structures, vehicles, transformers. A sample Hapag-Lloyd 20' flat rack measures about 5.6 m between corner posts and, depending on the series, has a gross weight of 34,000 to 45,000 kg. The carrier notes that full payload only applies when the weight is spread over the full length of the side rails; concentrated loads reduce the permitted weight. Lashing and load distribution must be agreed before booking.
Tank and flexitank
A tank container is a tank inside a 20' frame for liquids, including chemicals and dangerous goods depending on the tank class. A flexitank is a single-use bladder fitted inside an ordinary 20' container and used for liquids that are not dangerous goods, such as edible oils. For coconut oil imports from the Philippines it is one of the usual options, covered in our guide to importing coconut oil. Capacity, container requirements and flexitank acceptance differ between carriers, so confirm the terms before booking.
Choosing a container: checklist
- Weight or volume. Calculate gross weight and volume including pallets. If you hit the weight limit before filling the space, book a 20'; if the opposite, a 40' or 40' HC.
- Pallet height. Compare pallet height with the door opening, not the internal height. A pallet taller than about 2.29 m will not pass through the doors of a standard container.
- Temperature and humidity. Sensitive goods need a reefer or at least desiccants in a standard box.
- Loading method. Crane loading from above means open top; a forklift works with a standard container.
- Packaging and wood. Solid wood pallets and crates must meet ISPM 15; see our article on export packaging.
- VGM. Since 1 July 2016, under SOLAS regulation VI/2, the shipper must provide the verified gross mass of a packed container in good time; without it the container will not be loaded.
- Free time. Special equipment can be scarcer and free time for its return shorter; the charges for keeping it too long are explained in demurrage and detention.
The container type drives the freight cost, so it should be stated clearly in every quote. On Hiram, every quote states an Incoterms 2020 rule and place, and quotes are compared by total landed cost. If you are looking for a counterparty for a specific load, start with the market.
Sources
This article is for information only and is not legal, tax or customs advice. Rules and rates change: check the current official sources or consult an adviser before you decide.