What is a container prefix?
Every container number follows ISO 6346. The first three letters are the owner code and the fourth letter is the equipment category: U for freight containers, J for detachable equipment and Z for trailers and chassis. In MSCU1234567, the prefix is MSCU.
Why the prefix matters
The prefix tells you whether a box belongs to a shipping line or a leasing company. For carrier-owned boxes you can go straight to the carrier's website to track it. Leased boxes can travel with any line, so check your bill of lading to see who is carrying your cargo.
Not in the list?
The tool covers commonly seen prefixes. The full register of owner codes is kept by the Bureau International des Containers (BIC), where you can search any prefix.