By Luis Lopez, AI transportation consultant, CEO of Go Hub.io Holdings Corp and subsidiaries, and host of the Freight Guru Podcast
Ocean containers look alike from a distance, but the choice between a 20-foot, a 40-foot and a 40-foot high cube affects what you can load, what the freight costs per unit, and how the box moves once it leaves the port. Picking the wrong size usually means paying for empty space or finding out at the loading dock that the cargo does not fit.
This article covers the common dry container sizes, their approximate dimensions, and a practical way to decide between them.
The Three Sizes That Carry the Bulk of General Cargo
Standard dry containers are built to international standards so they can be stacked on ships, lifted by the same cranes, and carried on compatible chassis and rail cars. The figures below are approximate nominal dimensions. Actual interior measurements vary slightly by manufacturer and by container, so always confirm with your carrier or forwarder when a load is tight.
20-foot standard
- Exterior: about 20 feet long, 8 feet wide and 8 feet 6 inches tall
- Interior: roughly 19 feet 4 inches long, 7 feet 8 inches wide and 7 feet 10 inches tall
- Volume: approximately 33 cubic meters, or a little under 1,200 cubic feet
40-foot standard
- Exterior: about 40 feet long, 8 feet wide and 8 feet 6 inches tall
- Interior: roughly 39 feet 5 inches long, 7 feet 8 inches wide and 7 feet 10 inches tall
- Volume: approximately 67 cubic meters, or close to 2,400 cubic feet
40-foot high cube
- Exterior: about 40 feet long, 8 feet wide and 9 feet 6 inches tall
- Interior: the same floor area as a 40-foot standard, with roughly 8 feet 10 inches of interior height
- Volume: approximately 76 cubic meters, or close to 2,700 cubic feet
The high cube is one foot taller than the standard box. That extra foot adds meaningful volume without changing the footprint, which is why it has become a very common choice for light, bulky cargo.
One detail that catches shippers out is the door opening. It is smaller than the interior, both in width and in height. A crate that would fit inside the container on paper may not pass through the doors, so check the door dimensions for any tall or wide piece.
Volume Versus Weight: The Key Trade-Off
A 40-foot container offers roughly twice the volume of a 20-foot. It does not offer twice the weight capacity. The maximum gross weight of the two sizes is much closer than their volumes, and the 40-foot box itself is heavier when empty.
That leads to a general rule:
- Dense, heavy cargo such as stone, metal, tile, or bagged material often fits better in a 20-foot. The load reaches a weight limit long before it fills the space.
- Light, bulky cargo such as furniture, apparel, plastics or packaged consumer goods usually suits a 40-foot or a high cube. The load fills the space before weight becomes a concern.
I am deliberately not listing specific payload figures here. The maximum payload is marked on each container’s door, and it varies from one unit to another. More importantly, the weight you can legally move over the road is often lower than what the container itself is rated to carry. Road limits depend on the country or state, the chassis and axle configuration, and whether a permit is available. For one regional example of how those rules work, see our article on Florida overweight container permits and triaxle chassis limits.
Before loading a heavy container, confirm three things: the rated payload on the box, the limits your ocean carrier applies, and the road weight limits at both origin and destination. Shippers are also generally required to provide a verified gross mass for a packed container before it is loaded on a vessel.
How Many Pallets Fit
Pallet counts depend on pallet size, loading pattern, overhang and whether the cargo can be stacked. As a rough guide for a single layer on the floor:
- A 20-foot container is commonly cited as holding about 10 standard 48 by 40 inch pallets, or about 11 of the smaller Euro pallets.
- A 40-foot container is commonly cited as holding about 20 to 21 standard pallets, or about 23 to 24 Euro pallets.
Treat these as starting points. A few inches of overhang or a different pallet orientation can change the count, so a load plan drawn up with your supplier is worth the effort. A high cube does not add floor positions, but the extra height may allow taller pallets or a second layer when the cargo can be stacked safely.
Other Sizes and Types Worth Knowing
- 45-foot high cube. Longer than a 40-foot with high cube height. Used on certain trade lanes, and not available everywhere.
- Refrigerated containers. Insulated units with a built-in cooling system for temperature-controlled goods. Interior space is somewhat smaller than a dry box because of the insulation and machinery.
- Open top. A removable roof or tarp cover allows cargo to be loaded from above by crane, and can accommodate pieces taller than the door opening.
- Flat rack. A platform with end walls and no sides or roof, for machinery and oversized cargo.
- Tank containers. A tank within a container frame, for bulk liquids.
Specialized equipment is in shorter supply than standard dry boxes and typically needs more lead time to book.
How to Choose
- Calculate total volume and total weight. Get carton or pallet dimensions and weights from your supplier, and add them up.
- Identify which limit you hit first. If weight runs out first, lean toward a 20-foot. If space runs out first, lean toward a 40-foot or high cube.
- Check the tallest and widest piece against the door opening.
- Compare cost per unit, not cost per container. A 40-foot generally costs more than a 20-foot to ship but less than two of them, so the cost per cubic meter is often lower when you can fill it.
- Consider whether you need a full container at all. If your cargo fills only part of a 20-foot, shared space may be cheaper. Our article on FCL versus LCL shipping explains that comparison.
- Think about the inland move. Confirm that the delivery location can receive the size you choose and that suitable chassis are available. Our guide to chassis fees, splits and pools covers how that equipment works.
- Ask about equipment availability at origin. The size you want is not always on hand at every port or depot.
Common Mistakes
- Planning with exterior dimensions. Cargo has to fit the interior and pass through the door.
- Ignoring road weight limits. A container that is fine for the vessel can still be too heavy for the truck move at destination.
- Assuming a high cube is available. Confirm at booking, and confirm that your delivery site has the height clearance for it.
- Leaving space unsecured. A partly filled container needs blocking and bracing so cargo does not shift at sea.
Once the container size is settled, the rest of the process follows a predictable path, which we outline in our step-by-step guide to an import container move.
For more plain explanations of international freight and logistics, subscribe to the Freight Guru Podcast.
About the author: Luis Lopez is a Miami-based AI transportation consultant and logistics entrepreneur, the CEO of Go Hub.io Holdings Corp and subsidiaries, and host of the Freight Guru Podcast.