About this calculator
Every sea container has a unique number under ISO 6346, for example MSKU 123456 5. The first three letters are the owner code registered with the Bureau International des Containers (BIC), and the fourth letter is the equipment category: U for freight containers, J for detachable equipment (e.g. a clip-on genset) and Z for trailers and chassis. The next six digits are the serial number and the last digit is the check digit that catches typing errors.
This tool matches the prefix you type against the list of shipping lines and BIC prefixes curated on Stowage.id. One line usually owns many prefixes, from acquisitions or particular container series, and many containers are owned by leasing companies and rented to carriers, so the prefix owner is not always the operator moving your box. When you type a full number, the check digit is validated too, so you know the number on your documents is right before you track it or prepare the VGM.
Use it when you receive an empty container at the depot, when you match numbers on the B/L and packing list, or to find the right tracking site. For official and complete data, the container owner register is maintained by BIC through its BIC Code service; the list on Stowage.id may not include every prefix.
Worked example
Example list: Maersk (MAEU, MSKU, MRKU), MSC (MSCU, MEDU) and a lessor with the three-letter prefix MSK.
- Type MSKU 123456 5 → owner code MSK, category U (freight container). Exact match: Maersk (MSKU); the lessor's three-letter prefix (MSK) also matches and is listed after it.
- Type MSKJ → MSKU does not match because category J differs; only the three-letter MSK prefix matches.
- Type ME → prefix suggestion MEDU (MSC).
The owner data on this page comes from the Stowage.id shipping line list, which is updated regularly.
How to use it
Type a prefix or number
Enter the first 3–4 letters (e.g. MSKU) or the full container number from the door or your documents.
See the owner
Read the shipping line that owns the prefix, the U/J/Z category and a link to its site when available.
Check the check digit
For a full number, make sure the check digit is valid; if not, recheck the letters and digits on the document.