Shipment Tracking Guide
Shipping Container Number Format
Understand ISO 6346 container owner codes, equipment category identifiers, serial numbers, check digits, and carrier-prefix limitations.
A standard ISO container identification number contains four letters followed by seven digits. The format identifies registered equipment, but it does not always identify the shipping line currently transporting it.
Example: MAEU1234567. The first four characters form the owner and equipment code; the final seven characters contain the serial and check digit.
MAE: registered owner code.
U: freight container equipment category.
123456: equipment serial number.
7: check digit used to detect transcription errors.
Leased, exchanged, or partner equipment can move under a different shipping line. Use booking or bill of lading information when prefix ownership and operating carrier differ.
The check digit can validate the number structure, but it cannot prove the current carrier or shipment status.
Remove spaces before validation.
Confirm letters and digits carefully.
Use the operating carrier when known.
Try the bill of lading reference if container lookup is unavailable.
What this reference explains
Shipping Container Number Format is presented as an operational reference for freight teams, importers, exporters, and anyone interpreting shipping documents or tracking events.
How to apply the information
Use the definitions and examples together with the shipment contract, carrier instructions, and destination requirements. Keep the relevant reference attached to the shipment when it affects documents or operational follow-up.
Important verification step
Requirements and commercial practices can differ by country, carrier, commodity, and contract. Verify current legal, customs, airline, shipping-line, and handling requirements before acting.
Frequently asked questions
Why does the prefix show a different company from my carrier?
The prefix identifies registered equipment ownership. Containers can be leased or transported by another shipping line.
What does the fourth letter U mean?
U is the ISO equipment category identifier commonly used for freight containers.