20ft vs 40ft Shipping Containers: Which Size Is Right?
Choosing between a 20ft and a 40ft shipping container comes down to how much you need to store, the space you have to place it, and the access your truck can manage on delivery. Both are built to the same width and door height, so the real difference is length, and that changes floor area, volume and how easily a unit fits on your block. This guide breaks down the dimensions, capacity and typical Australian uses so you can match the size to the job.
External and internal dimensions compared
A standard 20ft container measures roughly 6.06 metres long, 2.44 metres wide and 2.59 metres high on the outside. A standard 40ft unit shares the same width and height but stretches to about 12.19 metres long, effectively two 20ft boxes end to end. The steel walls, corner castings and flooring take up some of that footprint, so the usable space inside is a little smaller than the external figures suggest.
Internally, a 20ft gives you close to 5.9 metres of length, around 2.35 metres of width and about 2.39 metres of clear height. A 40ft runs to roughly 12.03 metres long with the same internal width and height. The door opening on both sizes is about 2.34 metres wide and 2.28 metres high, which matters when you are moving pallets, machinery or furniture in and out.
Floor area and internal volume
Floor area is where the two sizes separate clearly. A 20ft offers roughly 13.8 square metres of floor, while a 40ft roughly doubles that to about 28 square metres. Internal volume follows the same pattern: a 20ft holds around 33 cubic metres and a 40ft around 67 cubic metres, so you get close to twice the packing space for a single delivery.
That doubling is worth weighing against cost and placement. A 40ft is not simply twice the price to buy or run, and it stores more per dollar of ground space. But it only pays off if you can actually fill it and fit it, which is why the length difference drives most decisions.
The high-cube option
Both 20ft and 40ft containers come in a high-cube version, which adds roughly 300 millimetres of external height, taking the outside to about 2.90 metres and the internal clear height to around 2.69 metres. The extra headroom is useful for tall pallets, stacked stock, bulky equipment, or any conversion where you want to fit insulation, lining and a ceiling without losing standing room.
High-cube 40ft units are common for workshops, offices and habitable fit-outs because the added height makes the interior feel far less cramped once the walls are lined. Keep the taller profile in mind for delivery, as low awnings, carport beams and gateways that clear a standard container may not clear a high-cube.
What each size realistically holds
A 20ft container comfortably takes the contents of a modest two or three bedroom home, a few motorbikes with room around them, garden and landscaping gear, or a wall of racked stock for a small business. As a rough guide it accepts around ten standard pallets on the floor, more if you stack. It suits sites where space is tight or where you simply do not have enough to justify the larger box.
A 40ft steps up to the belongings of a larger four or five bedroom home, a vehicle plus surrounding storage, or roughly twenty pallets across the floor. Trades and builders often choose the 40ft when one unit needs to cover tool storage, materials and a small work area at the same time. If you expect your storage needs to grow, the longer unit gives you headroom without a second delivery later.
Access, manoeuvring and delivery
The biggest practical constraint is not what fits inside the container but whether the container fits on your site. Most units arrive on a tilt-tray or side-loader truck, and the driver needs a clear, reasonably level and firm approach to place the box safely. A 20ft is far more forgiving on suburban blocks, tight driveways, laneways and sloping ground, and a tilt-tray generally needs a clear run of open space well beyond the container length to slide it off.
A 40ft demands a longer straight approach and a wider turning area, so kerbside trees, parked cars, low branches, narrow gates and soft lawn can all rule it out. Before you order, picture the truck reversing in and the container sliding to the ground, and check the standing space at the drop point. If access is doubtful, a side-loader can help, or two 20ft units may place where a single 40ft cannot.
Swinton Equipment Depot ships from Port Botany in NSW and delivers Australia-wide, with a flat delivery rate to mainland Australia, so you can compare sizes on a like-for-like basis whether the container is heading to Sydney, Melbourne, Brisbane or Perth.
Matching the size to the job
For home storage during a renovation or move, a fixed-position site store, or a small business overflow, a 20ft usually does the work and is easier to place. For a larger household, a growing stockholding, a combined store and workshop, or any conversion into an office or accommodation, the 40ft or 40ft high-cube gives the length and, in high-cube form, the height to make the space genuinely workable.
If a container is being converted with electrical fit-out, any fixed wiring and appliances should meet Australian electrical standards and carry RCM marking where required, and portable buildings that are relocated or connected to services may fall under state and local requirements. Sort the placement and any compliance questions before you commit to a size, since a container that cannot be delivered or approved is no bargain at any length.
Frequently asked questions
Close to it. A 40ft has roughly twice the floor area and internal volume of a 20ft because it shares the same width and height and simply doubles the length. Usable space is marginally less than a straight doubling once you account for the door and internal structure.
A high-cube is about 300 millimetres taller than a standard container, giving roughly 2.69 metres of internal height instead of about 2.39 metres. Both 20ft and 40ft sizes are available as high-cube, which suits tall loads and lined conversions but needs extra clearance on delivery.
A 20ft is generally easier because it needs less straight approach and turning space, and it copes better with tight driveways, laneways and sloping ground. A 40ft requires a longer, clearer run for the truck, so check your access before ordering the larger unit.