Shipping container dimensions and specifications — the numbers that actually matter

The short version

Shipping containers are built to an international standard, so a 20ft box from one manufacturer is within a few millimetres of a 20ft box from another. The figures below are the nominal ISO dimensions. Treat them as accurate to within roughly 10 mm on any individual unit, and measure the actual container before you build anything to fit it.

External dimensions

These are the numbers that decide whether it fits on your block, through your gate and inside your setback.

• 10ft: 2.991 m long × 2.438 m wide × 2.591 m high
• 20ft standard: 6.058 m × 2.438 m × 2.591 m
• 20ft high cube: 6.058 m × 2.438 m × 2.896 m
• 40ft standard: 12.192 m × 2.438 m × 2.591 m
• 40ft high cube: 12.192 m × 2.438 m × 2.896 m

Two things worth noticing. Every container is the same width — 2.438 m, eight feet — regardless of length or height. And a "20ft" is 6.058 m, not 6 m; a "40ft" is 12.192 m, not 12. That extra 58 mm and 192 mm has ruined more than one carefully measured slab.

A high cube is 305 mm taller than a standard and identical in every other external dimension. It is the single cheapest way to buy more usable space, and the reason people avoid it is usually headroom on the way in rather than headroom on the site.

Internal dimensions

What you actually get to use, floor to ceiling and wall to wall:

• 10ft: 2.831 m × 2.352 m × 2.393 m — about 15.9 m³
• 20ft standard: 5.898 m × 2.352 m × 2.393 m — about 33.2 m³
• 20ft high cube: 5.898 m × 2.352 m × 2.698 m — about 37.4 m³
• 40ft standard: 12.032 m × 2.352 m × 2.393 m — about 67.7 m³
• 40ft high cube: 12.032 m × 2.352 m × 2.698 m — about 76.4 m³

The wall loses you about 43 mm a side, the roof and floor structure about 200 mm between them. Corrugation means the internal width varies slightly depending on whether you measure at a peak or a trough — the figure above is the safe one, measured at the narrowest point.

The door opening — the number nobody looks up

This is the measurement that causes the most trouble, and it is on almost no spec sheet people actually read.

On both a 20ft and a 40ft standard, the door aperture is roughly 2.343 m wide and 2.280 m high. On a high cube the width is the same and the height goes to about 2.585 m.

So the opening is about 9 mm narrower than the internal width and — the important one — 113 mm lower than the internal ceiling. The door header sits below the roof line. Something that fits inside the container with room to spare may not go through the doors standing up.

If you are putting in a vehicle, a machine, a tank, a caravan, a boat on a trailer or a piece of plant, the door aperture is your constraint, not the internal height. Measure the tallest fixed point of the thing you are loading and compare it to 2.280 m, not 2.393 m.

Weights — tare, payload and gross

Three numbers, and people mix them up constantly. Tare is the empty weight of the container. Payload is what you may legally put in it. Gross is the two added together, and it is stamped on the door of every unit.

• 10ft: tare about 1,300 kg
• 20ft standard: tare about 2,200 kg, max gross 30,480 kg (some rated 24,000 kg)
• 40ft standard: tare about 3,800 kg, max gross 30,480 kg
• 40ft high cube: tare about 3,900–4,000 kg, max gross 30,480 kg

Note that a 40ft has nearly twice the volume of a 20ft and the same maximum gross weight, so its usable payload is lower. A 40ft fills up on volume; a 20ft fills up on weight. That is why heavy goods travel in 20ft units and light bulky goods travel in 40ft.

For storage on your own block, gross rating is mostly irrelevant — what matters is the tare, because that is what the truck has to lift and what the ground has to carry. Two-and-a-bit tonne on a 20ft, just under four on a 40ft.

Ground footprint, and the bit about corner castings

A container does not rest on its base. It rests on the eight corner castings — steel blocks at each corner, each roughly 178 mm × 162 mm. All of the weight goes through those.

For a 20ft that means four bearing points at 5.853 m centres lengthways and 2.259 m centres across. For a 40ft, 11.985 m by 2.259 m. If you are laying pads, those are the centres to set them at.

A 40ft also has intermediate castings at the 20ft position, which is how two 20ft units can travel on a 40ft trailer. On soft ground a 40ft is often better supported on six pads rather than four.

What actually fits

The practical version of all of the above:

• Australian standard pallets (1165 mm square): 10 on the floor of a 20ft, 20–21 in a 40ft.
• Euro pallets (1200 × 800 mm): 11 in a 20ft, 23–24 in a 40ft.
• A car: most sedans, hatches and small utes go into a 20ft. It is tight, the doors will not open once it is in, and the 2.280 m door height rules out anything with a roof rack or a raised suspension. Dual cabs and long-wheelbase utes generally want a 40ft.
• A three-bedroom house: the furniture and effects of an average three-bedroom home will typically fit a 20ft, packed properly. Four bedrooms and up, plan on a 40ft.
• Standard-length timber (5.4 m) fits a 20ft. 6.0 m lengths do not — they are longer than the 5.898 m internal.

The height you forget: the container on the truck

A container on a tilt-tray or a trailer sits roughly 1.1 to 1.3 m off the ground before you add the container itself. A 2.591 m standard therefore travels at around 3.7 to 3.9 m, and a 2.896 m high cube at around 4.0 to 4.2 m.

That is what has to clear your power line, your tree limbs, your carport and your gateway arch — not the 2.591 m you measured on the spec sheet. And during a tilt-tray delivery the bed goes up at a steep angle before the container slides off, so the clearance needed mid-delivery is greater again.

It is the most common reason a delivery is turned around at the gate, and it is entirely avoidable with one photograph taken standing at the placement spot looking straight up.

A few specifications that are not dimensions

• Floor: 28 mm marine-grade plywood on steel cross-members at roughly 300 mm centres. It will carry a forklift, which is more than most sheds will do.
• Roof: corrugated steel, designed to take a person walking carefully and nothing else. It is not a load-bearing deck, it is not a platform, and water ponds on it. Do not store anything up there.
• Walls: corrugated Corten weathering steel, about 2 mm. Strong vertically, which is why containers stack nine high loaded, and much weaker once you cut a hole in one. Any cut for a door or window wants a welded frame back in.
• Doors: both doors on the one end, swinging to 270 degrees. You need about 2.4 m of clear space behind the door end to open them fully — plan that into the placement, because a container against a fence with its doors facing the fence is a very expensive garden ornament.

Which size, in one line each

10ft when space is genuinely tight — small yards, courtyards, tight industrial sites. It costs more than a 20ft because they are scarce, so buy one because you need the footprint, not to save money.

20ft for the great majority of storage jobs. It fits on almost any block, it is delivered by the cheapest truck and it is the easiest size to sell on later.

40ft when you have the run and the access. Roughly twice the space for far less than twice the money, and by a wide margin the cheapest storage per square metre — provided the site can take a 12 m vehicle and a side loader.

High cube whenever you can clear the extra 305 mm on the way in. The additional headroom costs very little and it is the difference between a workshop you can stand up in comfortably and one you cannot.

Before you build anything to fit

Every figure on this page is nominal. Manufacturers work to tolerances, repairs change things slightly, and a 30-year-old unit has been knocked about. If you are pouring a slab, framing an opening, building a roof over it or fitting shelving to the millimetre, wait until the container is on site and measure it. Ring us on 1300 263 976 and we will give you the size, tare and door dimensions of the actual unit we are quoting you.