How the container loading calculator works
A load plan tells you how many boxes go into a container, how they stack, and whether weight or space runs out first. This calculator builds that plan in your browser, so nothing is sent to a server, and it recalculates as soon as you stop typing. It tries several layouts: an EB-AFIT heuristic that builds the load layer by layer, a single-orientation grid when you have one box type, and grids banded by box height when you mix sizes. Every candidate goes through the same checks, and the one that loads the most wins. Each item can rotate freely (all six orientations), stay upright (this side up, turning only on the floor plane) or keep the exact orientation you entered; upright is the default. You can also mark items as non-stackable (nothing may be placed on top, not even the same item), require them to be loaded on the floor rather than on top of other freight, cap how many high they stack, or set the maximum weight each box can carry on top. Two limits are checked separately. First, the calculator checks whether each item fits through the door opening in at least one allowed orientation; items that don't are left out of the plan and flagged. Second, if the total weight goes over the container's payload, boxes are removed from the top down until it doesn't.
Why work this out before booking? A full container load (FCL) is priced at a flat rate per container, whether you fill it or not, so empty space is space you've paid for. Less than container load (LCL) is charged by the cubic meter, with your cargo sharing space with other shippers. If your boxes don't all fit, the overflow means a second container or an LCL shipment on top of the FCL. The result shows the 3D load plan, space and weight utilization, and what limits the load: weight, space, or nothing (everything fits). You can share the setup as a link, export it to CSV, or paste item rows straight from Excel.
How to estimate a container load by hand
The quickest estimate is to divide the container's rated capacity by the box volume, but that number is a ceiling, not a load. Boxes can't be cut to fill the gaps, so a realistic count comes from a grid: how many whole boxes fit along the interior length, width and height in a given orientation.
The calculator does the grid for you and goes further. It compares an EB-AFIT layer-building heuristic with grid layouts and keeps the one that loads the most; for a single box type, the result never drops below the best single-orientation grid. It then applies the rotation setting, stacking rules, the door opening and the payload, and draws the load plan in 3D so you can see where each box goes.
- Measure the outer carton (L × W × H) and calculate its volume: 60 × 40 × 40 cm = 0.096 m³.
- Divide the container's rated capacity by the box volume and round down. For a 40ft High Cube, 76.3 ÷ 0.096 gives 794 boxes. Treat this as a ceiling you won't reach.
- Work out a grid for each allowed orientation: interior length ÷ box length, width ÷ box width, height ÷ box height, each rounded down, then multiplied. With the 60 cm side along the length, that's 20 × 5 × 6 = 600; with the 40 cm side along the length, 30 × 3 × 6 = 540. Keep the higher one.
- Check the leftover gaps. In the 600-box layout, 3 cm of length, 35 cm of width and 30 cm of height are left, all smaller than the box's shortest side (40 cm), so nothing else fits.
- Apply the real-world limits: whether boxes can rotate, which ones are non-stackable or must stay on the floor, whether each item fits through the door opening, and whether the total weight stays within payload.
- For mixed box sizes, enter every item in the calculator and let it build the 3D load plan.
Example: 60 × 40 × 40 cm boxes in a 40ft High Cube
One 40ft High Cube container, loaded with identical 60 × 40 × 40 cm outer cartons weighing 8 kg each. Boxes stay upright, so they can turn on the floor plane but not tip over.
The container's interior is 1,203 × 235 × 270 cm, and the box height of 40 cm stacks six high in the 270 cm interior height with 30 cm to spare.
| Box size | 60 × 40 × 40 cm |
| Box volume | 0.096 m³ |
| Interior (L × W × H) | 1,203 × 235 × 270 cm |
| Rated capacity | 76.3 m³ |
| Volume ceiling | 76.3 ÷ 0.096 → 794 |
| 60 cm along length | 20 × 5 × 6 = 600 |
| 40 cm along length | 30 × 3 × 6 = 540 |
| Gaps left (L / W / H) | 3 / 35 / 30 cm |
| Cargo volume | 57.6 m³ (75.5%) |
| Cargo weight | 4,800 kg (16.8% of payload) |
600 boxes fit: 194 fewer than the 794 that volume alone suggests (24.4% less), because every leftover gap is smaller than 40 cm. The calculator also returns 600 with boxes upright, and 650 if you allow free rotation. At 4,800 kg the load runs out of space long before it reaches the 28,620 kg payload.
Container sizes compared: space and weight limits
Rated capacity is the geometric limit. Cargo denser than the density limit reaches the payload before the container is full. The last column is a single-orientation grid of upright 60 × 40 × 40 cm boxes and its share of rated capacity. A 40ft High Cube has the same floor as a 40ft dry but 31 cm more interior height in the calculator (305 mm on Hapag-Lloyd specs) and 8.6 m³ more capacity.
| Container | Interior (L × W × H) | Door opening (W × H) | Rated capacity | Payload | Density limit | 60 × 40 × 40 cm grid |
|---|---|---|---|---|---|---|
| 20ft dry | 590 × 235 × 239 cm | 234 × 228 cm | 33.2 m³ | 28,200 kg | 849 kg/m³ | 225 (65.1%) |
| 40ft dry | 1,203 × 235 × 239 cm | 234 × 228 cm | 67.7 m³ | 28,800 kg | 425 kg/m³ | 500 (70.9%) |
| 40ft High Cube | 1,203 × 235 × 270 cm | 234 × 257.7 cm | 76.3 m³ | 28,620 kg | 375 kg/m³ | 600 (75.5%) |
| 45ft High Cube | 1,355 × 235 × 270 cm | 234 × 257.7 cm | 86.1 m³ | 27,700 kg | 322 kg/m³ | 660 (73.6%) |
Common mistakes
- Entering product dimensions instead of outer carton dimensions. Packaging and board thickness add up across hundreds of boxes, and the plan shows more boxes fitting than will actually go in. Measure the carton as it will be loaded.
- Dividing capacity by box volume and booking on that number. For 60 × 40 × 40 cm boxes in a 40ft High Cube, the division says 794 but a grid fits 600. Count whole boxes along each internal dimension instead.
- Forgetting the door opening. Doors are smaller than the interior (234 × 228 cm against 235 × 239 cm on a dry container in the calculator), so a large item that fits inside may not get through the door. Check the largest pieces against the door width and height.
- Ignoring payload. Cargo denser than about 849 kg/m³ in a 20ft dry or 375 kg/m³ in a 40ft High Cube reaches the weight limit before the space is full. At 1,000 kg/m³, a 40ft High Cube hits its payload when only 37.5% full.
- Skipping stacking rules. If some boxes are non-stackable or must be loaded on the floor, a plan that stacks everything overstates the count. Set these rules per item.
- Assuming a 40ft dry and a 40ft High Cube stack the same. A 40 cm box stacks five high in a dry container's 239 cm (39 cm left above) and six high in a High Cube's 270 cm (30 cm left above).
- Treating the result as the guaranteed maximum, or as the final stowage. The packing is a heuristic, and the calculator doesn't reserve room for dunnage, securing or bracing. Allow for them by leaving space above the cargo or entering custom container dimensions.
How do you calculate how many boxes fit in a container?
Start with the outer carton dimensions and work out how many boxes fit along the container's interior length, width and height, rounding each down to a whole box, then multiply the three. Try each orientation the box is allowed to take and keep the best. For a 60 × 40 × 40 cm box in a 40ft High Cube (1,203 × 235 × 270 cm inside), that gives 20 × 5 × 6 = 600 boxes. Dividing the container's capacity by the box volume only gives a ceiling (794 boxes in this case) that no real load reaches. For mixed box sizes, stacking rules, door limits and payload, a container loading calculator does the arithmetic for you.
How many boxes fit in a 40ft High Cube container?
It depends on the box size, not just the container's volume. A 40ft High Cube is rated at 76.3 m³ by Hapag-Lloyd and 76.2 m³ by ONE. With 60 × 40 × 40 cm boxes kept upright, 600 fit in a single grid, which is 57.6 m³ of cargo, or 75.5% of the rated 76.3 m³. Dividing 76.3 m³ by the 0.096 m³ box volume suggests 794, but the space left over along the length (3 cm), width (35 cm) and height (30 cm) is smaller than the box's shortest side, so no more boxes fit.
Why can't I fill 100% of the container?
Boxes come in whole units, and the container's interior is rarely an exact multiple of the box size. The gaps left at the end, side and top are usually too small for another box. For 60 × 40 × 40 cm boxes kept upright, a single grid fills 65.1% of a 20ft dry container's rated capacity, 70.9% of a 40ft dry, 75.5% of a 40ft High Cube and 73.6% of a 45ft High Cube. Rotation limits, non-stackable items, the door opening and the payload can lower the count further.
Why is the calculator's result lower than container volume divided by box volume?
Volume division assumes boxes can be cut to fill every gap. The calculator places whole boxes inside the real internal dimensions, so leftover gaps smaller than a box stay empty. It also follows the rotation setting, stacking rules (non-stackable, floor only, how many high a box may stack, maximum load on top), the door opening and the payload. The packing is a heuristic: it finds a good arrangement quickly but can't guarantee the best possible one, and if it runs out of its search budget the result is marked as approximate. For a single box type, the result is never lower than the best single-orientation grid.
What does the door check do?
It checks, item by item, whether each piece can get through the door opening in at least one of its allowed orientations. The door is smaller than the interior: on carrier specs for 20ft and 40ft dry containers the door opening is 2,340 mm wide against an interior width of 2,350–2,352 mm, and 2,280–2,292 mm high against 2,390–2,395 mm inside. The calculator uses 234 × 228 cm for dry containers and 234 × 257.7 cm for High Cubes. Items that can't pass are left out of the load plan and listed separately. The check doesn't restrict how items are placed once inside, and it's skipped for a custom container if you don't enter door dimensions.
Will the calculator warn me about weight limits?
Yes. If the total weight of the boxes goes over the container's payload (for example 28,620 kg for a 40ft High Cube), the calculator removes boxes from the top layers down and reports weight as what limits the load. Dense cargo reaches the weight limit before the space is full; light cargo runs out of space before reaching the weight limit. The crossover is payload ÷ capacity: about 849 kg/m³ for a 20ft dry, 425 kg/m³ for a 40ft dry, 375 kg/m³ for a 40ft High Cube and 322 kg/m³ for a 45ft High Cube. The calculator only checks the container's payload. Road and rail limits, such as the 80,000 lb gross vehicle weight on US Interstate highways, aren't included, so check them separately.
Should I enter the product dimensions or the carton dimensions?
Enter the outer carton dimensions: the size of the box as it will be loaded, including packaging, cushioning and the thickness of the corrugated board. Product dimensions understate the space each box takes, so the calculator would show more boxes fitting than will actually go in.
Can the calculator split a shipment across several containers?
Yes. In the default auto mode it considers all four standard sizes (20ft, 40ft, 40ft High Cube and 45ft High Cube), smallest first. It picks the smallest container that takes everything left at 95% utilization or less; if none does, it takes one above 95% that still fits everything. If nothing fits the whole remainder, it fills a container and moves on to the next. It plans up to 8 containers and shows anything left over. You can exclude sizes from auto mode, or choose a single container type and a number of containers yourself.
Floor loaded or palletized: how does the calculator handle pallets?
By default boxes are floor loaded, stacked directly on the container floor with no pallets. In single-container mode you can palletize the boxes first, using a standard pallet (48 × 40 in, 121.9 × 101.6 cm), a euro pallet (120 × 80 cm) or a custom pallet. The defaults are a maximum height of 180 cm including the pallet, a maximum load of 1,000 kg per pallet, no overhang and no double stacking (pallets stacked two high). The pallet's deck height (14.5 cm for the standard pallet, 14.4 cm for the euro pallet) and its weight (25 kg in the calculator) are added automatically, so they count toward the container's height and payload.
How is container utilization calculated?
Space utilization is the volume of the boxes loaded divided by the container's usable interior volume, worked out from its internal dimensions minus any space you leave above the cargo. Weight utilization is the loaded weight divided by the container's payload. Both are shown as whole percentages. For example, 100 boxes of 60 × 40 × 40 cm at 8 kg each fit in one 20ft dry container at 29% space utilization (9.6 m³ ÷ 33.137 m³).
Sources
All calculations run in your browser. Figures are based on published standards, carrier-published values and nominal dimensions, so check them against your carrier's own numbers before you book.
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