What is FCL (full container load)?
The shipper collects an empty container from the carrier's depot, loads and seals it at its own premises or a warehouse, and has it trucked to the terminal before the cargo cut-off, with the verified gross mass declared. The sealed box travels unopened to destination, where the consignee collects it and returns the empty. The common sizes are 20-foot, 40-foot and 40-foot high cube.
FCL means exclusive use, not that the box is physically full. With LCL, by contrast, the shipper shares a container and pays by volume or weight. As a rough guide, LCL usually makes sense below about 13–15 m³; above that, a 20-foot container is often cheaper and faster, because there is no consolidation at origin or unpacking at destination.
Choose the container by whichever limit binds first. A 20-foot box offers about 33.2 m³ inside, a 40-foot 67.7 m³ and a 40-foot high cube 76.4 m³, but heavy cargo reaches the weight limit long before the space runs out, and road weight rules at either end can be stricter than the container's own maximum. FCL shipments also incur demurrage and detention once free time is exceeded.