Container Loading Calculator

Using the container loading calculator

The calculator answers one planning question: how many identical items fit in one shipping container? It tries every way of turning the item through its three axes, counts how many fit with a straight, gap-free stack, and reports the best arrangement.

1. Pick the length unit under Metric (mm, cm, m, in or ft). Pounds replace kilograms when you choose inches or feet.
2. Enter the item's width, length and height. Which edge you call which does not matter, because every orientation is tried.
3. Optionally enter the item weight. With it, the result also shows the total cargo mass and compares it with the container's maximum load.
4. Choose a container type. Select Custom if yours is different; then give its internal width, length and height and, if you entered an item weight, its maximum cargo load.
5. Press Calculate.

The results list the maximum number of packets, how much of the container's volume they fill, the number of stacking levels, the volume of the container and of one packet, the cargo mass (when a weight is given) and a sentence describing how to orient each packet.

Container sizes and load limits are typical values and every manufacturer differs slightly. Results are planning estimates, not a loading plan: confirm with your freight forwarder or shipper before booking. See our disclaimer.

Standard container sizes used by the calculator

The eight predefined types follow the common ISO series 1 sizes. Real containers are often built a little roomier than the minimum internal size in the standard, so these figures are the internal sizes commonly delivered, together with a typical maximum cargo load (payload) after subtracting the empty weight of the box.

A high cube is about 27 cm (265 mm) taller inside than the standard box, which adds roughly 11% to its volume. When your own container is different, for instance a refrigerated unit with thick insulation, use the Custom option and enter its measured inside dimensions.

How the count is calculated

Finding the best possible packing of boxes is a famously hard optimisation problem. The calculator avoids it by assuming that every item is oriented the same way, like bricks in a wall. There are then only six ways to match the item's width, length and height to the container's width, length and height.

packets = ⌊W ÷ a⌋ × ⌊L ÷ b⌋ × ⌊H ÷ c⌋W, L, H are the container's internal width, length and height; a, b, c are the item's sizes assigned to those three directions; ⌊ ⌋ means rounding down to a whole number.

For each of the six assignments the three whole-number counts are multiplied, and the largest product wins. If two arrangements tie, the first in the order width/length/height, width/height/length, length/width/height, length/height/width, height/width/length, height/length/width is shown. The third count, along the container's height, is the number of stacking levels.

Example. An item measures 500 × 600 × 400 mm (width × length × height) and goes into a 40' standard container (2,350 × 12,030 × 2,390 mm). The six arrangements give:

Two arrangements reach 400, so the first one in the order is reported: line the width up with the container width, the length with the container length and the height with the container height, giving 5 levels. Each packet has a volume of 0.5 × 0.6 × 0.4 = 0.12 m³, so 400 of them occupy 48 m³ out of 67.5665 m³, a utilization of 71.04%.

Another item, 700 × 300 × 500 mm, does best with its width across the container, its height along it and its length vertical: 3 × 24 × 7 = 504 packets (78.32% utilization).

Checking the cargo weight

A container can be full by volume long before it is full by weight, or the other way round. When you enter an item weight the calculator multiplies it by the packet count and compares the total with the container's maximum cargo load. If the total is higher, it says so instead of showing a percentage.

Example. Cubes of 500 mm weighing 400 kg each: a 20' standard container has room for 176, which would weigh 70,400 kg, far above its 28,200 kg limit. The weight-limited number is ⌊28,200 ÷ 400⌋ = 70 cubes, which would fill only 70 × 0.125 = 8.75 m³ (26.4% of the volume). The calculator reports the volume-based count and warns you, so reduce the quantity yourself when the warning appears.

For a custom container you must provide the maximum load as well, otherwise the load cannot be checked.

Utilization versus ease of loading

Mixing orientations or filling the leftover strip at the end of the container with turned items can squeeze in a few more units. In practice the crew then needs a detailed diagram, and mistakes cost time and can leave the load unstable. A uniform layout, where every level repeats the same pattern, is quicker to load, easier to count and simpler to secure, so it is usually the better trade for a few percent of space.

That is why the calculator offers simple stacking. The Complex option is shown for completeness but currently returns the same figures.

• Leftover space. A utilization well below 100% is normal: a leftover strip that is narrower than one item cannot hold another item.
• Pallets. If goods travel on pallets, first work out the pallet load with the pallet calculator, then treat the loaded pallet as the item here.
• Real clearances. Doors, uneven floors, dunnage, air bags and lashing all take space the calculator ignores.
• Item volume. To check the volume of a single box, try the volume of a box calculator.

Assumptions and limits

• All items are identical, rigid and rectangular, and nothing is stacked beyond what the height allows. Round or irregular goods need a different method.
• Sizes are converted to whole millimetres and any fraction is dropped, so an item entered as 2.39 cm is treated as 23 mm. For small items, enter millimetres to avoid this.
• Because of that rounding down, very small items can occasionally appear to fill more than 100% of the volume.
• The count assumes you can place items right up to the walls. Allow for packaging, protrusions and handling gaps when you plan the real load.
• An item larger than the container in every orientation gives zero packets.