ISO 6346 defines how a container is uniquely marked. The code consists of four letters (owner prefix plus category identifier "U" for freight containers), a six-digit serial number and a boxed check digit, which makes it possible to detect transposed digits. Example: MSCU 123456 7.
Below it is the size and type code (e.g. "45G1" for a 40 ft High Cube standard container). The shipping line or leasing company can be identified via the owner prefix and the BIC register. When buying a used container, the number is important for clearly identifying the specific container in the quote and invoice.
Also: ISO containers explained simply.
Last updated: 8 September 2026 · Editor: Coin Container Team, Hamburg