Shipping Container Types and Sizes: 20ft, 40ft, and Special Containers
Once you decide to ship by ocean, the next question is "which container, and how much fits?" Containers are standardized in type and size, so knowing the dimensions and load limits lets you plan your freight and stowage in advance.
This guide covers standard container dimensions, the special container types, and how to choose the right container for your cargo.
Why Container Dimensions Matter
Every container has a limit on both volume (CBM) and weight. Exceed it and you need another container; fall far short and LCL (consolidated small shipments) may be cheaper. Knowing the dimensions tells you how many containers you need and whether FCL or LCL wins.
Standard Dry Container Dimensions
These are the most common general-cargo (dry) containers. Internal dimensions and CBM follow ISO standards and vary slightly by manufacturer.
| 20ft | 40ft | 40ft High Cube (HC) | |
|---|---|---|---|
| Internal length | ~5.9m | ~12.0m | ~12.0m |
| Internal width | ~2.35m | ~2.35m | ~2.35m |
| Internal height | ~2.39m | ~2.39m | ~2.69m |
| Internal volume | ~33 CBM | ~67 CBM | ~76 CBM |
| Max payload | ~28 tons | ~28 tons | ~28 tons |
Volume is a theoretical maximum. In practice you fill about 85 to 90 percent of it to allow for loading access and irregular cargo, so a 20ft holds roughly 25 CBM and a 40ft about double.
20ft, 40ft, or High Cube: Which to Choose
- 20ft: best for heavy but compact cargo, or small loads.
- 40ft: more than double the volume of a 20ft, but a similar maximum payload. So the lighter and bulkier your cargo, the better a 40ft fits.
- 40ft High Cube (HC): same length and width as a 40ft, but about 30cm taller. It gives more volume for light, bulky cargo such as apparel or finished electronics.
The key question is whether volume or weight hits its limit first. Heavy cargo tops out on weight; light cargo tops out on volume.
Special Container Types
Non-standard cargo cannot go in a dry container. These special containers match the cargo's characteristics.
- Reefer (refrigerated): temperature-controlled for food, pharmaceuticals, and other sensitive cargo. Available in 20ft and 40ft, with slightly less internal volume for the cooling unit.
- Open Top: an open roof for crane loading from above, used for over-height cargo like machinery.
- Flat Rack: no roof or side walls, for over-width or heavy cargo such as equipment and large materials.
- Tank: a tank structure for liquids, chemicals, and edible oils.
Others, such as the 45ft high cube (~86 CBM) and ventilated containers, are used depending on the cargo.
Checklist for Choosing a Container
- Calculate total CBM and total weight first: whichever hits its limit first decides the container size and count.
- Plan for 85 to 90 percent utilization: you rarely fill the theoretical volume, so leave room.
- Check road weight limits: even within the container's payload limit, inland road axle-load rules may cap what you can actually load.
- Consider LCL for small loads: if you cannot fill a container, compare LCL and FCL and pick the cheaper option.
Knowing container dimensions and CBM lets you size your shipment before you even request a quote.
This guide is for general information. Exact dimensions and load limits vary by carrier, manufacturer, and lane. Confirm the carrier's specs before shipping.
Frequently asked questions
What is the difference between a 20ft and a 40ft container?
A 40ft has more than double the internal volume of a 20ft (about 67 CBM versus 33 CBM), but a similar maximum payload of around 28 tons. So a 40ft suits light, bulky cargo, while heavy cargo can hit the weight limit even in a 20ft.
How is a high cube (HC) container different from a standard 40ft?
It has the same length and width as a 40ft but is about 30cm taller inside (~2.69m). That adds volume (about 76 CBM), which helps when shipping light, bulky cargo.
How many CBM fit in one container?
In theory about 33 CBM for a 20ft and 67 CBM for a 40ft. In practice, allowing for loading access and cargo shape, you fill roughly 85 to 90 percent, so about 25 CBM in a 20ft and roughly double in a 40ft.
What are the special container types?
Reefers (refrigerated) for temperature-sensitive cargo, open tops for over-height cargo, flat racks for over-width or heavy cargo, and tanks for liquids and chemicals. General cargo uses standard dry containers.
Which container should I choose?
Calculate total CBM and total weight to see which hits its limit first. Light and bulky cargo suits a 40ft or high cube; heavy cargo suits a 20ft. If you cannot fill a container, LCL consolidation may be cheaper.
