A standard shipping container is 7 feet 8 5/8 inches (2,352 mm) wide on the inside, measured wall to wall. This holds true for both 20-foot and 40-foot general purpose containers, since all standard ISO containers share the same cross-section. The length changes, but the interior width stays virtually identical.
Standard Container Internal Width
Whether you’re loading a 20-foot or 40-foot dry container, the usable width between the corrugated steel walls is 2,352 mm, or just under 7 feet 9 inches. The external width of both sizes is 8 feet (2,438 mm), so you lose roughly 3.5 inches to the steel wall panels on each side.
Containers with steel floors measure almost identically. A 40-foot steel-floor container comes in at 2,350 mm (7 feet 8 1/2 inches) wide inside, just 2 mm narrower than the wooden-floor version. For practical purposes, the difference is negligible.
Door Opening Width
The rear cargo doors are slightly narrower than the interior itself. On a standard 20-foot container, the door opening measures 2,340 mm (7 feet 8 1/8 inches), about half an inch less than the wall-to-wall width. That half inch matters if you’re trying to slide something in that barely fits. Whatever passes through the doors will have clearance once inside, but the doorframe is your true bottleneck.
Refrigerated Container Width
Refrigerated containers (often called reefers) sacrifice interior width for insulation. A 20-foot or 40-foot high cube reefer has an internal width of 2,294 mm, roughly 7 feet 6 inches. That’s about 2.3 inches narrower than a standard dry container on each side, thanks to the foam insulation lining the walls. If you’re planning a temperature-controlled shipment, account for this tighter fit when sizing your cargo or pallets.
Pallet-Wide Containers
Standard containers were designed before the widespread use of Euro pallets (1,200 mm x 800 mm), and two Euro pallets placed side by side don’t quite fit between the walls of a regular container. Pallet-wide containers solve this by stretching the interior width to 2,422 mm (7 feet 11 inches), roughly 4 inches wider than standard, while keeping the same external dimensions as a regular ISO container. This lets you load two pallets across without wasted gaps, which can significantly improve how much product fits in each shipment.
Pallet-wide reefer versions go even further, with an internal width of 2,440 mm. These are especially common on routes where Euro pallets dominate, like intra-European trade.
Quick Reference by Container Type
- 20-foot or 40-foot standard dry: 2,352 mm / 7 ft 8 5/8 in
- 20-foot or 40-foot reefer: 2,294 mm / approx. 7 ft 6 in
- 40-foot high cube pallet-wide: 2,422 mm / 7 ft 11 in
- 45-foot pallet-wide reefer: 2,440 mm / approx. 8 ft
- Door opening (standard 20-ft): 2,340 mm / 7 ft 8 1/8 in
What This Means for Loading
With just under 7 feet 9 inches of usable width, a standard container can fit most vehicles, machinery, and palletized freight without issue. Two standard North American pallets (48 x 40 inches each) placed with their 40-inch sides across the container width total 80 inches, leaving about 12 inches of clearance. That tight but workable margin is why forklift operators typically load pallets lengthwise down the container rather than forcing a snug side-by-side fit.
If you’re converting a container into a workspace, living space, or storage unit, the interior width of roughly 7 feet 8 inches defines your floor plan. After adding insulation, framing, and wall finishing, you might lose another 4 to 6 inches on each side, bringing usable room width down to around 7 feet or slightly less. Planning wall assemblies with that starting dimension in mind will save you from unpleasant surprises mid-build.