Containers
Containers Overview

Containers Overview

Containers are the vessels you fill when creating a load plan. In LOP, a container is any enclosed space that holds cargo: a standard ISO shipping container, a truck trailer, a custom-dimensioned vessel, or even a warehouse pallet position. Before the optimizer can arrange your items, it needs to know the exact internal space available.

What Is a Container in LOP?

Every load plan is built around one or more containers. A container definition tells LOP:

  • The internal usable dimensions — the actual space available after structural framing (not the external footprint)
  • The maximum payload — the highest total cargo weight the vessel can legally carry
  • The door dimensions — width and height of the loading opening, used to confirm items can physically enter
  • Optional attributes such as tare weight, maximum floor load rating, and lashing point positions

LOP uses these parameters to enforce physical constraints during optimization. Items that exceed the door opening, push past the inner walls, or collectively exceed the max payload are flagged immediately — before the plan leaves the editor.

Types of Containers

ISO Shipping Containers

LOP includes a built-in library of standard ISO shipping containers with accurate internal dimensions sourced from international standards:

TypeCommon Name
20' GPStandard 20-foot General Purpose
40' GPStandard 40-foot General Purpose
40' HC40-foot High Cube
45' HC45-foot High Cube

These are the most widely used container types in international ocean freight. All dimensions in the library reflect internal (usable) space, not the outer steel shell.

Trucks and Road Trailers

LOP supports common truck and trailer formats used in road freight: North American dry vans (48'/53') and box trucks, European curtainsiders (standard and mega) and box trailers, the flatbed and open-deck family (flatbed, step deck, double drop / lowboy, removable gooseneck, EU platform), and specialized equipment including liquid tankers and the 25.25 m LHV / EuroCombi road train.

Air Cargo Unit Load Devices (ULDs)

Standard air freight ULD types are available in the container library for air shipment planning. ULDs have fixed certified dimensions and weight limits set by the IATA.

Sea Containers

Beyond the standard ISO dry boxes, the sea catalog also includes reefers, open-tops, flat racks, and ISO tank containers.

Specialized Equipment

The catalog covers vessels that don't pack like a plain box — liquid tankers (planned by fill, not stacking) and the two-body EuroCombi road train. If your equipment isn't in the catalog, see Custom Containers.

Multi-Container Plans

LOP supports adding multiple containers to a single plan. This is useful for large shipments that require more than one vessel, or when you want to compare how a shipment fills different container types.

When a plan contains multiple containers:

  • The optimizer distributes items across all containers automatically
  • Each container gets its own score for utilization, weight balance, and stability
  • A tab bar at the bottom of the editor shows all containers with their current Space Utilization
  • You can switch between containers to inspect each one independently in the 3D viewport

Multi-container optimization uses a Worst-Fit assignment strategy: items are sorted by volume (largest first) and each is placed into the container with the most remaining capacity that still fits it, spreading the load evenly across containers. After initial assignment, a cross-container rebalancing pass attempts to relocate any unplaced items into containers with remaining space.

Container Library

All 50 built-in container types are available to every LOP account without any configuration.

Open Container Library from the left sidebar to choose which types appear in the container picker when creating plans — select only the vessels your operations use to keep the picker list clean. See Container Preferences for details.

Next Steps

Quantity & GroupsStandard Containers