Container Dimensions Guide
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Before you sketch a floor plan, fall in love with a render or ring a container yard, you need to know exactly what you are working with. A shipping container looks simple from the outside, but the millimetres matter. Every layer you add inside (frame, insulation, lining, flooring) eats into a space that is already only a little over two metres wide. Get the dimensions right at the start and the rest of the design falls into place. Get them wrong and you end up with a bed that won't fit, a ceiling the building surveyor won't accept, or a door that clashes with a cross member.
This guide covers the sizes you will actually come across in Australia, what you are left with once the container is fitted out, and the numbers that drive design decisions on every container home.
The containers you will actually find
Containers are built to the ISO 668 family of standards, so a 40 ft box from one maker is almost identical to a 40 ft box from another. Small differences (usually under 10 mm) do exist between manufacturers, so always measure the actual unit before you order joinery or windows.
The four sizes that matter for homes are:
20 ft standard (GP): the classic short box. Easy to transport on a tilt tray and a good size for studios, bathrooms, kitchens and bedroom modules.
20 ft high cube (HC): the same footprint, 305 mm taller. Perfect for habitable rooms, but surprisingly hard to buy in Australia because shipping lines use relatively few of them.
40 ft standard (GP): double the length of a 20, same height as a 20 ft standard.
40 ft high cube (HC): the workhorse of container homes. Plentiful, well priced per square metre, and tall enough for compliant ceilings.
You will also see 10 ft units (handy for plant rooms and storage), 45 ft high cubes (rare, awkward to transport) and "pallet wide" boxes that are a little wider than standard. For a home we almost always work with 20 ft and 40 ft high cubes.
The key numbers
These are typical figures. Use them for planning, then confirm on the unit you buy.
20 ft standard (GP)
External (L × W × H): 6,058 × 2,438 × 2,591 mm
Internal (L × W × H): 5,898 × 2,352 × 2,393 mm
Door opening (W × H): 2,340 × 2,280 mm
Internal floor area: approx. 13.9 m²
Tare weight (empty): approx. 2,200 to 2,300 kg
20 ft high cube (HC)
External (L × W × H): 6,058 × 2,438 × 2,896 mm
Internal (L × W × H): 5,898 × 2,352 × 2,698 mm
Door opening (W × H): 2,340 × 2,585 mm
Internal floor area: approx. 13.9 m²
Tare weight (empty): approx. 2,300 to 2,400 kg
40 ft standard (GP)
External (L × W × H): 12,192 × 2,438 × 2,591 mm
Internal (L × W × H): 12,032 × 2,352 × 2,393 mm
Door opening (W × H): 2,340 × 2,280 mm
Internal floor area: approx. 28.3 m²
Tare weight (empty): approx. 3,700 to 3,800 kg
40 ft high cube (HC)
External (L × W × H): 12,192 × 2,438 × 2,896 mm
Internal (L × W × H): 12,032 × 2,352 × 2,698 mm
Door opening (W × H): 2,340 × 2,585 mm
Internal floor area: approx. 28.3 m²
Tare weight (empty): approx. 3,800 to 3,950 kg
A couple of things jump out. The width never changes: every standard container is 2,438 mm wide outside and about 2,352 mm inside. And the difference between a standard and a high cube is all in the height, which turns out to be the single most important number in a container home.
Why high cube matters: ceiling height
Under the National Construction Code, habitable rooms in a house (bedrooms, living areas) generally need a ceiling height of at least 2.4 m. Kitchens, bathrooms, laundries and hallways can go down to 2.1 m. Your building surveyor will confirm the exact requirement for your design.
Now do the maths on a standard container. You start with about 2,393 mm internally. Add a floor overlay (say 15 to 25 mm), ceiling insulation and battens (50 to 90 mm) and a ceiling lining (10 mm) and you are at roughly 2,270 to 2,320 mm. That is below 2.4 m, so a standard height box struggles to meet the code for a bedroom or living room.
A high cube starts at about 2,698 mm. After the same build-up you are sitting at roughly 2,570 to 2,620 mm, comfortably over 2.4 m with room to spare for downlights and a more generous layer of roof insulation. That is why we recommend high cubes for any room you will live or sleep in. Standard height containers still work well for bathrooms, laundries, storage and plant rooms.
What you are left with inside
The honest answer to "how wide is a container home?" is: narrower than you think. Here is how the internal width typically disappears:
Start: 2,352 mm between the corrugated steel walls.
Wall framing each side: 35 to 70 mm, depending on whether you use battens, 64 mm steel studs or 70 mm timber.
Insulation: sits inside the frame (or is sprayed onto the steel), but spray foam and thermal breaks can add a few millimetres.
Lining each side: 9 to 12 mm for plywood or plasterboard.
A typical fitted-out container ends up 2,150 to 2,250 mm wide inside. If you insulate on the outside and clad over it, you can keep more of the internal width (closer to 2,280 mm) because the inside only needs a thin batten and lining.
That finished width drives the whole layout:
Beds: a queen bed is 1,530 x 2,030 mm. It fits across the width of a container, wall to wall, with access from the foot end. Running it lengthways leaves room for walkways either side but uses more of the length.
Kitchens: a 600 mm deep bench along one wall leaves about 1,550 to 1,650 mm of floor, which is plenty for one cook and a walkway. A galley with benches on both sides works only with shallower (450 mm) cabinetry on one side.
Hallways: allow at least 900 mm of clear walkway, ideally 1,000 mm, if the hallway runs beside rooms in the same container.
Bathrooms: a 20 ft container comfortably takes a full bathroom and laundry. The width suits a shower across one end, with the vanity and toilet along the side walls.
Structure: where the strength really is
A container is essentially a steel frame with corrugated skin. Understanding which parts do the work tells you where you can and cannot cut.
Corner posts and corner castings: carry the stacking loads. Loaded containers are stacked many high on ships, so the corners are enormously strong. Foundations, tie-downs and lifting all work through the corner castings.
Top and bottom side rails: the long members along the top and bottom edges. They tie the corners together and span between supports.
Floor cross members: steel channels running across the container under the floor, supporting heavy point loads like forklifts.
Corrugated walls: roughly 1.6 to 2.0 mm Corten steel. The corrugations act as a shear panel, stiffening the whole box. Cut out a big section and you lose that stiffness, which is why large openings need a steel frame.
Roof: the roof sheet is not designed to carry much at all. The ISO test is a load of about 300 kg spread over a small area, roughly one person standing on it. Never plan on a roof garden, snow load or heavy solar array without an engineered roof structure.
Floor: usually 28 mm marine plywood (sometimes bamboo) screwed to the cross members. Strong, but often treated with pesticides. See our Interiors and Insulation guides.
Weight, transport and site access
A 40 ft high cube weighs close to 4 tonnes empty and more once it is fitted out in the factory (a finished module can reach 7 to 10 tonnes depending on the fit-out). Plan delivery early:
20 ft containers can usually go on a tilt tray truck and be slid onto piers, if the site is flat and there is room to reverse.
40 ft containers normally need a side loader truck or a crane truck. A side loader needs a firm, level, reasonably wide area beside the footings to put its legs down.
Cranes are the most flexible option for sloping or tight sites, but you will need to check reach, ground bearing, power lines and road permits.
Measure the access road, gateways, overhanging trees and turning circles before you commit. Tasmanian rural driveways can be steep, soft and narrow, so a site visit with the transport company is always worth it.
Buying a container: new, one trip or used?
New or "one trip": shipped once from the factory (usually in Asia) with cargo, then sold. Straight, clean, minimal rust and the best starting point for a home.
Cargo worthy (CW): used but certified fit for shipping. Some dents and surface rust, but structurally sound.
Wind and water tight (WWT): older units that keep the weather out but may have rust, dents and patched floors. Fine for sheds, risky for homes.
When you inspect a container, check the CSC data plate on the door (it shows the manufacture date and, often, the floor treatment), look along the roof for dents and ponding, check the corners and bottom rails for rust, and open and close the doors to make sure the box is square.
Designing with modules
Because the width is fixed, container homes are designed by combining modules. Two 40s side by side, with most of the joining walls removed, gives you a space about 4.7 m wide, which feels like a normal house. A 20 ft module can be a bathroom and laundry hub, a bedroom or a BBQ studio. Stacking a module on top (supported through the corner castings) adds a second storey without adding footprint.
That is exactly how our range works. POD1 and POD2 are single 20 ft units, BOX joins two 20s, ROAM combines a 40 and a 20, NEST joins two 40s, and STACK2 adds a second level. Our HUB and BED modules are 20 ft units designed to add a kitchen and bathroom or an extra bedroom to an existing home.
Interbode tips
Measure the actual container you are buying before you order windows, doors or joinery. Ten millimetres here and there adds up fast in a 2.35 m wide space.
Use high cubes for any room you will live or sleep in.
Draw your plan with the finished internal width (about 2,200 mm), not the raw 2,352 mm.
Keep openings clear of the corner posts and, where possible, line them up between the floor cross members.
Think about delivery on day one. The best design in the world is no good if a 40 ft container can't get up the driveway.
If you would like help working out which container sizes suit your block and brief, get in touch for a quote or browse our Library for real container homes and how they were put together.
This guide is general information only. Every site and design is different, so always confirm dimensions on the actual container and get advice from your building surveyor and a structural engineer before you build.