Internal and external dimensions, cubic capacity and tare weight for 40 ft and 40 HC containers, with the extra internal height a high cube actually gives you.
A 40-foot general purpose container has the same external width and height as a 20-foot box and twice the length. Internally it gives roughly double the volume — a little more than double, because the end walls are a fixed cost paid once rather than twice.
That is the whole commercial logic of the format. If your cargo fills before it weighs, a 40-foot box moves close to twice the volume for one set of handling charges, one set of documents and one slot on a chassis.
Where it stops working is dense freight. Payload does not double with length, so a box loaded with anything heavy reaches its weight limit with a great deal of space unused. That is why steel, tiles, minerals and machinery parts move in 20s.
| Figure | 40 ft GP (1AA) | 40 ft HC (1AAA) |
|---|---|---|
| External L × W × H | 12,192 × 2,438 × 2,591 mm | 12,192 × 2,438 × 2,896 mm |
| Internal L × W × H | 12,032 × 2,352 × 2,393 mm | 12,032 × 2,352 × 2,698 mm |
| Door W × H | 2,340 × 2,280 mm | 2,340 × 2,585 mm |
| Capacity | 67.7 m³ (2,390 cu ft) | 76.4 m³ (2,698 cu ft) |
| Maximum gross mass | 30,480 kg | 30,480 kg |
Source: ISO 668. External dimensions and maximum gross mass are exact and hold for every compliant box. Internal dimensions, door opening and capacity are nominal and differ from manufacturer to manufacturer. Imperial figures are rounded down from the metric.
A high cube has the same footprint as a 40-foot standard box and approximately 30 cm more internal height.
Whether that height is worth anything depends entirely on how your goods stack. If your cartons or pallets stack to a height that leaves 30 cm unused in a standard box, the high cube gives you an extra layer and the economics are obvious. If they stack to a height that already fills a standard box, the extra 30 cm is air you pay to move.
The cost of the height is not only money. A high cube raises the loaded height of whatever vehicle carries it, and on routes with tight clearances that can be the difference between running and not running.
| Figure | 40 ft GP | 40 ft HC | Difference |
|---|---|---|---|
| External height | 2,591 mm | 2,896 mm | +305 mm |
| Internal height | 2,393 mm | 2,698 mm | +305 mm |
| Door height | 2,280 mm | 2,585 mm | +305 mm |
| Capacity | 67.7 m³ | 76.4 m³ | +8.7 m³ |
Source: ISO 668, nominal. The 305 mm is one foot and all of it is height — length, width and maximum gross mass are identical on both formats. Internal figures differ between manufacturers, so treat the gain as about a foot rather than exactly 305 mm until you have the box.
A high cube is heavier empty than a standard 40-foot box, because there is more steel in the walls. That extra tare comes straight out of payload if you are running to a gross limit.
The three figures — tare, payload, gross — are stamped on each individual box's CSC plate and vary between manufacturers and between build years. For a specific box, read the plate rather than a table. A published figure is a typical value, and typical is not what a weighbridge measures.
ISO 668 fixes one figure in this line and no more: the 30,480 kg maximum gross mass, identical for 20 ft, 40 ft and 40 HC. Tare sits outside the standard, which is why payload — gross minus tare — is arithmetic done per box rather than a number anyone can publish for containers in general.
Getting value out of a high cube means designing the stack around the height rather than discovering it afterwards.
Three things to check. Does your carton height divide into the internal height with an acceptable remainder — and would a small change in carton dimensions remove the waste entirely? Can your handling equipment reach the top layer, given that a forklift working inside the box has less headroom than the box does? And does your cargo stack safely to that height, or does the top layer need restraint it would not have needed in a standard box?
When those three answers are good, a high cube is the cheapest volume in containerised freight. When any of them is bad, a standard box is the better buy.
