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The three dry containers most shippers meet are the 20 ft, the 40 ft and the 40 ft high cube. All three are 8 ft (2.438 m) wide on the outside; the 20 ft is 19 ft 10.5 in (6.058 m) long, the two 40s are 40 ft (12.192 m) long, and the high cube is a foot taller than the standard 40, at 9 ft 6 in (2.896 m). Usable space inside is smaller and varies by line and unit, so treat the internal figures below as approximate. These are general-purpose (dry) containers. Reefers, open-tops and flat racks have different internal sizes, and the smaller and larger sizes are not covered here, so ask the carrier for the spec of those.
External dimensions: the fixed part
External sizes are the ones that are standardised. A GoFreight guide says external sizes are the ISO 668 nominal dimensions (GoFreight). ISO 668 is the defining standard; it is paywalled, so the figures here come from two readable sources that agree with each other: GoFreight and HZ Containers.
| Container | Length | Width | Height |
|---|---|---|---|
| 20 ft | 6.058 m 19 ft 10.5 in | 2.438 m 8 ft 0 in | 2.591 m 8 ft 6 in |
| 40 ft | 12.192 m 40 ft 0 in | 2.438 m 8 ft 0 in | 2.591 m 8 ft 6 in |
| 40 ft high cube | 12.192 m 40 ft 0 in | 2.438 m 8 ft 0 in | 2.896 m 9 ft 6 in |
Feet and inches are converted from the millimetre figures at exactly 25.4 mm per inch, so 2,896 mm is 114.0 in, or 9 ft 6 in. External sizes tell you how much deck, ship slot or trailer space a box takes up. They do not tell you what fits inside.
Internal dimensions: approximate, varies by line and unit
Walls, floor and roof take space, and builders differ in how much. DSV, a forwarder that publishes these figures, says the dimensions “may vary depending on the container manufacturer, the age of the container and the container owner” (DSV dry container). The values below are the ones DSV and HZ Containers both give, except the high cube door height, rounded to centimetres. HZ lists millimetres, and the feet and inches are converted from those.
| Container | Length | Width | Height | Door width | Door height |
|---|---|---|---|---|---|
| 20 ft | about 5.90 m 19 ft 4 in | about 2.35 m 7 ft 8.5 in | about 2.39 m 7 ft 10 in | about 2.34 m 7 ft 8 in | about 2.28 m 7 ft 6 in |
| 40 ft | about 12.03 m 39 ft 5.7 in | about 2.35 m 7 ft 8.5 in | about 2.39 m 7 ft 10 in | about 2.34 m 7 ft 8 in | about 2.28 m 7 ft 6 in |
| 40 ft high cube | about 12.03 m 39 ft 5.7 in | about 2.35 m 7 ft 8.5 in | about 2.70 m 8 ft 10 in | about 2.34 m 7 ft 8 in | about 2.58 m 8 ft 5.6 in |
The door height is the figure to check a tall load against. Sources differ slightly on the high cube door height: DSV gives 2.58 m and HZ Containers 2,585 mm. Plan with the lower figure and confirm with the carrier.
Volume, calculated from the approximate internal dimensions above, is about 33 m³ for the 20 ft, 68 m³ for the 40 ft and 76 m³ for the high cube. These are calculated, not rated capacities.
What actually differs between the three
- 20 ft vs 40 ft: only length changes. Width, internal height and door size are the same, so a 40 is simply a longer tunnel.
- High cube: the extra foot is all height, on the outside and the inside. Floor area is the same as a standard 40. It helps with light, tall cargo and with stacked pallet loads that would otherwise touch the roof, and it does nothing for floor space.
- The door is the tightest point. Interior height is more than the door height, so a load that fits inside may still not go through the door. Measure the load against the door opening, not the interior.
Worked example (illustrative numbers only). A pallet stacked to 2.20 m high clears a 2.28 m door with 0.08 m (8 cm) to spare. A stack 2.35 m high is under the interior height but taller than the door opening, so it cannot be loaded upright.
Turning sizes into a load plan
Dimensions alone do not give you a count of pallets or cartons. How pallets sit across the interior width depends on the pallet size and orientation. The pallets per container tool lets you enter interior dimensions and pallet sizes, including 48 x 40 in and Euro pallets, and works the count out for you, so you do not have to convert by hand. To fit cartons onto a pallet first, use the pallet calculator, and to get cargo volume, the cubic feet calculator multiplies length, width and height for you. Land transport has its own limits; for a trailer see how many pallets fit in a 53 ft trailer.
Before you rely on a number
- Use external sizes for space on a ship, trailer or chassis, and internal sizes for what fits in the box.
- Ask the carrier or depot for the spec of the container you will actually get. Internal sizes differ between lines and units, as DSV notes.
- Leave a margin. Do not plan a load that fits with nothing to spare.
- Payload is not given here because published figures vary by line and unit. Check the container’s CSC plate or the carrier spec.
Sources
- GoFreight: shipping container dimensions guide (external dimensions).
- HZ Containers: dimensions of transport containers (external, internal and door dimensions in mm).
- DSV: dry container dimensions and DSV: high cube dry container (internal and door dimensions, variation note).
- ISO 668, the defining standard for external dimensions (paywalled, not read in full).
Figures retrieved 2026-11-09. Carrier specifications can change, so confirm anything critical with your carrier.