How the container planner calculates
The planner uses the container’s internal length, width and height and treats your cargo as identical rectangular units.
- Cartons: it tries each allowed orientation (only the upright ones if “keep upright” is ticked), finds the best floor pattern for that orientation — including mixed two-block patterns where some rows are turned 90° — and stacks as many layers as the internal height allows.
- Pallets: it finds the best floor pattern for the pallet footprint. Pallets are single-tier unless you tick double-stacking, in which case it stacks as many tiers as fit the height.
- Payload: it divides the container’s maximum payload by the weight of one unit. The final answer is the lower of the space and weight limits.
Worked example
Euro pallets (120 × 80 cm, 150 cm high, 500 kg each) in a 20ft dry container (589.8 × 235.2 cm inside): one row of pallets placed lengthwise (80 cm across the width) plus one row turned crosswise (120 cm across) uses 200 cm of the 235.2 cm width. Along the length that gives 7 + 4 = 11 pallets, totalling 5,500 kg — well within payload. In a 40ft the same pattern gives 25 in theory, but with only 3 cm to spare most loaders achieve 23–24, which is why the planner has a clearance field: enter 1 cm and the 40ft result becomes 23.
Loading reefers
Refrigerated containers have thicker insulated walls and a T-floor for air circulation, so they are smaller inside than dry boxes. Cargo must not be stacked above the red load line marked near the top of the side walls, and should not block the T-floor at the door end, or cold air cannot circulate. Treat reefer heights in this tool as the maximum and plan a little lower.
Practical tips
- Allow some clearance for loading by forklift and for bulging cartons. Space and weight results are theoretical maximums.
- Heavy cargo often “weighs out” before it “cubes out”, especially in 20ft containers. Check road limits too: some countries cap gross vehicle weight well below the container’s rating.
- Distribute weight evenly along the length and secure the load with dunnage, airbags or lashing.
Frequently asked questions
How many pallets fit in a 20ft container?
Typically 11 Euro pallets (1200 x 800 mm) or 9 standard pallets (1200 x 1000 mm or 48 x 40 in) on a single tier; the inside width is too narrow to fit two standard pallets side by side the long way. A 40ft holds about 23–25 Euro pallets or 20–21 standard pallets.
What are the internal dimensions of a 40ft high cube?
Typically about 12.03 m long, 2.35 m wide and 2.70 m high inside, for roughly 76 m³ of capacity. It is 30 cm taller than a standard 40ft container.
Why does my container weigh out before it fills up?
Dense cargo such as tiles, metal parts or liquids reaches the maximum payload before the space is used. The planner shows both limits so you can see which applies.
Are reefer containers smaller inside?
Yes. Insulation and the refrigeration unit reduce internal space. A 40ft high cube reefer has about 67–68 m³ versus about 76 m³ for a dry 40ft high cube, and cargo must stay below the red load line.
Does this tool handle mixed carton sizes?
Not yet; it plans one carton or pallet size at a time. For mixed loads, run each size separately to estimate the share of the container it needs.