ISO container dimensions
Intermodal shipping containers follow ISO 668, which fixes their external footprint so they stack and lock identically on any ship, train or chassis worldwide. Internal space, door opening and payload vary by type. This reference lists the common containers with external and internal dimensions, capacity and weights, switchable between metric and imperial.
How it works
External dimensions are standardised: every 20ft container is 6.058 m long and every 40ft is 12.192 m, both 2.438 m wide, so corner castings align for stacking and lifting. Internal dimensions are smaller because of wall corrugation, corner posts and the door frame — the door opening width and height limit what can be loaded. Cubic capacity is the manufacturer-rated usable volume, always a few percent below internal length × width × height. The imperial toggle converts metres to feet (× 3.28084), m² to ft², m³ to ft³ and kg to lb.
Choosing between standard and high-cube
The high-cube container is approximately 30 cm (one foot) taller externally and internally than the standard equivalent. For a 40ft high-cube, internal height rises from about 2.39 m to 2.69 m, adding roughly 8–9 cubic metres of usable space over the standard 40ft. That extra height becomes decisive when stacking goods that cannot be double-stacked: tall pallets, rolled textiles, furniture, light machinery. The trade-off is height restrictions on road transport — some destinations impose lower bridge clearances or permit heights that a high-cube load may violate. Always check the maximum height with your inland haulage provider before specifying a high-cube for door-to-door shipments.
Pallets per container: practical loading figures
| Container type | Euro pallets (1,200×800 mm) | Standard GMA pallets (1,219×1,016 mm) |
|---|---|---|
| 20ft standard | 11 (floor load, single tier) | 9–10 |
| 40ft standard | 23–25 | 20–21 |
| 40ft high-cube | 23–25 (same floor) | 20–21 |
High-cube adds vertical space, not floor space, so pallet counts match the 40ft standard unless you are double-stacking lighter loads.
Weight vs volume: which limit controls?
A 20ft container has a typical maximum payload of around 28,000 kg and an internal volume of about 33 cubic metres. A 40ft high-cube has roughly the same payload but about 76 cubic metres. For dense cargo like machinery, steel coils, or stone tiles, the payload limit is almost always reached before the cube is full — and in those cases the 20ft’s stronger corner-casting rating relative to volume can make it more suitable. For light, bulky goods such as apparel or plastics, the 40ft high-cube maximises the value per container-slot because it can fill the cube at a weight well below the structural limit.
Reefer containers and internal space loss
Refrigerated (reefer) containers sacrifice internal length and height to house the cooling machinery at one end and to provide thicker insulated walls. As a result a reefer 20ft has noticeably less usable length and volume than a dry 20ft of the same external size. When planning reefer loads, always use reefer internal dimensions from this reference rather than the dry-container figures as a proxy — the difference can be enough to lose a full pallet row.
Gross-weight limits vary by transport leg
An ISO container’s structural maximum gross weight is one limit; the road, rail, and port weight limits at origin, transit, and destination are often stricter. Road limits in Europe, for instance, restrict axle loads in ways that frequently keep a heavy 20ft well below the container’s ISO maximum. Confirm legal weights with your freight forwarder for every transport leg, not just the sea portion.