A container number is the unique identifier of a shipping container under the ISO 6346 standard: four letters followed by seven digits, for example MSCU1234567. The letters are the owner code plus a category letter, usually U; the final digit is a check digit that validates the whole number.
The number is stencilled on the door, sides, and roof, and stays with the box for life. The first three letters identify the registered owner (the prefix), the fourth letter the equipment category, and the six serial digits plus check digit complete it. Alongside the number, ISO 6346 also defines the size-and-type code you see near it, such as 22G1 or 45G1.
One container number appears in many systems at once: the carrier’s bookings, the terminal’s yard system, customs filings, and every tracking event. That ubiquity is what makes it the most reliable key for following a shipment.
Container number, bill of lading, and booking number are the three references carriers accept for tracking; the container number is the one that never changes hands mid-journey. Paste it into TrackingMCP to follow the box across carriers, or validate the number first if a typo is suspected.
A container number is the unique identifier of a shipping container under the ISO 6346 standard: four letters followed by seven digits, for example MSCU1234567. The letters are the owner code plus a category letter, usually U; the final digit is a check digit that validates the whole number.
ISO 6346 assigns category letters: U for freight containers, J for detachable equipment, Z for trailers and chassis. Since tracked boxes are freight containers, U dominates.
Not legitimately. Owner codes are registered internationally and serials are unique per owner. A duplicate in paperwork almost always means a typo, which the check digit will usually expose.
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More in Identifiers & codes: Container check digit · Container prefix (owner code) · Booking number · SCAC code · UN/LOCODE · IMO number · MMSI · TEU & FEU · Browse all 106 terms →