Is this an optimal container packing algorithm?

No. It compares uniform axis-aligned grids for identical rectangular cartons. Depending on the mode, it tests one, two or six carton orientations, with one orientation used throughout each candidate. Mixed arrangements and irregular loading can produce other capacities. The chart and table expose the tested scope, so the result should be used as a reproducible grid estimate.

Where do the container presets come from?

They use Hapag-Lloyd’s example equipment specifications, inspected on October 14, 2026. The linked pages provide interior dimensions, door opening and payload examples, while explaining that actual containers vary by manufacturer. Every field remains editable. Confirm your assigned equipment and any lower applicable booking or transport weight allowance before using a preset as an operational loading input.

Does payload include the empty container?

The allowed cargo payload field excludes the container’s tare weight. It includes cartons and the entered reserve for dunnage or restraint materials. The calculator subtracts that reserve before dividing by packed carton weight. If your document gives maximum gross container mass, subtract the actual tare first and check any lower permitted cargo limit for the equipment and journey.

How are door openings checked?

For each tested orientation, the carton’s width and height must fit the entered clear door width and height. The model assumes individual cartons enter in their loading orientation. It does not test diagonal entry, turning inside, pallets or loading equipment. A passing size check is therefore one necessary geometric condition within the model, not a complete loading-access assessment.

What does volume utilization mean?

It is the outside volume of the allowed carton quantity divided by your entered usable interior volume. Weight limits can lower this percentage even when the geometric grid has more positions. It does not include the physical volume of dunnage or infer free access space. Reduce usable dimensions for space reservations and review the separate securement and handling plan.

Can I mix carton sizes or rotate only some cartons?

This implementation accepts one packed carton size and weight per calculation, with one uniform orientation in each candidate. It does not combine different products or partial regions with different rotations. Calculate separate scenarios to inspect their individual capacities, then use a planner that explicitly models the mixed shipment when you need a shared loading arrangement and practical restraint plan.

Container Loading Calculator | Complete Calculators

What does this container loading calculator show?

A container loading calculator estimates the number of identical cartons that fit inside an entered rectangular cargo space. This tool compares the carton orientations you permit, checks individual carton entry against the door opening, and caps quantity by usable interior dimensions, permitted stacking layers and available payload after dunnage. It also estimates containers needed for an order.

Container names describe an equipment family, not a guarantee of one exact interior measurement or load allowance. The selectable 20-foot standard, 40-foot standard and high-cube starting values come from Hapag-Lloyd example equipment pages. Their dimensions and payload remain editable. Use the specification for your assigned container and reduce the space or weight allowance when the actual operation requires it.

The model separates physical room from mass capacity. A light carton may run out of positions first, while a heavy carton may reach the payload limit with unused interior space. The comparison table lists both the geometric count and allowed count for each tested orientation. The volume percentage describes carton outside volume relative to the usable interior you entered, rather than a measure of actual securement quality.

Door access is another independent condition. A carton that fits inside may be too wide or tall to pass through the door in its selected loading orientation. This tool excludes that orientation. It assumes cartons enter individually in the same orientation used inside, without diagonal movement or turning after entry. Fully built pallets, forklifts and other loading equipment need their own access assessment.

Every candidate is a uniform grid using one orientation throughout. Allowing six orientations can help inspect products that may be placed on different faces, but you must supply that permission. The calculator does not combine several carton types or orientations, optimize irregular spaces, or establish a complete loading and restraint procedure. Its useful output is an inspectable grid estimate with explicit assumptions.

Uniform grids for identical cartons only. Door checks assume each carton enters in its loading orientation. Mixed packing, aisles, restraint, floor loading and load stability are outside this estimate.

Method and calculation

The entered carton L, W and H are mapped onto the container’s length, width and height for each permitted orientation. Fixed mode tests only L × W × H. Upright mode also tests W × L × H. Six-orientation mode tests every assignment of the three carton dimensions to the three container axes. All cartons in a candidate use the same assignment.

Whole-carton counts along each interior axis are rounded down. The vertical count is additionally capped by your permitted layer specification. The door test requires the candidate carton’s width and height to fit within the clear opening; a failing candidate has zero allowed capacity even if its hypothetical interior grid has positions. No angled entry or interior reorientation is attempted.

Allowed payload excludes container tare but includes the dunnage reserve entered here. Subtract that reserve, divide by packed carton weight and round downward to find the mass-limited count. The lower geometric and mass counts determine candidate capacity. The highest feasible tested capacity is selected, then order quantity is divided across containers with a possible remainder. No global packing optimality is asserted.

Formula or lookup rule

Geometric cartons = floor(interior length / oriented carton length) × floor(interior width / oriented carton width) × min(floor(interior height / oriented carton height), permitted layers); weight capacity = floor((allowed payload − dunnage) / packed carton weight); allowed cartons = min(geometric cartons, weight capacity) for orientations passing the door check; containers = ceil(order quantity / allowed cartons).

Confirm the equipment: Select an example or enter custom usable interior dimensions, clear door opening and allowed cargo payload.
Measure packed cartons: Enter outside dimensions and packed weight for identical cartons.
Set loading constraints: Reserve dunnage weight, enter the permitted layer count and allow only product-compatible orientations.
Compare and record: Calculate capacities, inspect door exclusions and payload limits, then save the selected grid and shipment count.

Worked examples

An upright grid in a 20-foot example

Use the 590 × 235.2 × 239.5-centimeter interior example with 40 × 30 × 25-centimeter cartons and a five-layer cap. The L × W × H arrangement fits 14 along, seven across and five high, giving 490 geometric cartons. Rotating upright fits 19 along, five across and five high, giving 475. Both individual carton orientations fit the example door. With carton weight 11 kilograms, payload 28,130 kilograms and 100 kilograms reserved for dunnage, geometry limits capacity to 490 cartons. An order of 1000 needs three containers.

Payload leaves unused volume

Keep those dimensions but set the available cargo payload to 2000 kilograms, including a 100-kilogram dunnage reserve. The remaining 1900 kilograms hold only floor(1900 / 11) = 172 cartons. Both upright geometric grids have more positions, so the mass cap reduces each to 172. Cargo plus the reserve weighs 1992 kilograms at capacity. The volume result is based on those 172 cartons, not all 490 hypothetical positions. This unused geometric room does not justify exceeding an equipment, road or booking weight restriction.

A carton fits inside but not through the door

Consider a custom interior 600 centimeters long, 240 wide and 240 high, with a door 230 centimeters wide and 220 high. A fixed 100 × 235 × 100-centimeter carton has interior positions but exceeds the clear door width. Its allowed count is zero. If the product permits upright floor rotation, W × L × H gives a 100-centimeter width and 100-centimeter height at the door and can be tested as a feasible grid. This checks size only; actual loading access and maneuvering remain operational questions.

Practical applications

Estimate identical-carton capacity: Use measured finished cartons and confirmed equipment dimensions to calculate a reproducible count. The comparison records which orientation was tested and whether space, payload or carton stacking limits reduced its quantity.
Compare equipment examples: Start with the standard or high-cube example, then replace values with your assigned equipment. A taller interior may add a layer only if carton height, door entry and the permitted layer specification allow it.
Plan a repeated shipment: Enter a whole order quantity to estimate container count and the final remainder. The result assumes the same equipment and capacity for every container and reserves the entered dunnage mass per container.
Screen permitted product orientations: Compare two upright rotations or all six dimension assignments when packaging instructions allow them. The chart makes the capacity effect visible; it does not decide whether a product may be shipped on its side.
Check mass sensitivity: Run a heavier packed sample or a lower allowed payload separately. Keep the space dimensions unchanged so the comparison reveals when the governing constraint shifts from grid positions to available cargo mass.
Prepare a load-planning discussion: Export the selected grid, door checks and assumptions for a forwarder or loading team. The record provides inspectable inputs for a more complete loading plan with restraint, distribution, handling equipment and reserved physical space for the actual shipment.

Tips for useful results

Confirm the assigned container’s actual minimum usable dimensions, door opening and permitted payload. Equipment examples are starting specifications. Reserve physical space by reducing the usable interior inputs, and reserve packing and restraint mass with the dunnage field. Enter cargo payload without container tare; do not confuse it with the equipment’s maximum gross mass.

Use the most restrictive applicable equipment, booking or route mass allowance. A layer count must come from product and carton specifications rather than available headroom alone. Side orientations should be enabled only when packaging and contents permit them. An orientation passing the door-size check still needs a practical loading path; the model does not include forklifts, aisle space or turning maneuvers.

Related calculations

Dimensional Weight Calculator — Compare actual and dimensional package weight with an editable divisor, rounding rules and per-package shipment totals.
Pallet Calculator — Plan uniform carton layouts, weight-limited pallet capacity, shipment pallet counts and the final partial pallet with a layer diagram.
TI/HI Calculator — Find cartons per layer and complete layers per pallet using measured carton sizes, height limits and gross-weight constraints.
Packaging Cost Calculator — Estimate packaging cost per order and batch from boxes, protection, whole tape rolls, material allowance and packing labor.

Sources and references

Hapag-Lloyd: 20-foot Standard container example specifications. Live equipment page; publication date unspecified. Section: Inside dimensions, door opening and weight. Accessed 2026-10-14. Example equipment dimensions and payload; actual units vary by manufacturer. Confirm the assigned container and applicable transport limits.
Hapag-Lloyd: 40-foot Standard container example specifications. Live equipment page; publication date unspecified. Section: Inside dimensions, door opening and weight. Accessed 2026-10-14. Example equipment dimensions and payload; these are editable starting values, not a booking or loading approval.
Hapag-Lloyd: 40-foot Standard High Cube example specifications. Live equipment page; publication date unspecified. Section: Inside dimensions, door opening and weight. Accessed 2026-10-14. Example high-cube interior and door dimensions. Payload must be confirmed for the assigned equipment and route.
NIST: Guide to the SI, Appendix B.8. SP 811 online conversion table. Section: Inch, foot and avoirdupois pound entries. Accessed 2026-10-14. Supports length and mass conversions. Unit changes preserve measurements; they do not select a carrier tariff.

Container Loading Calculator