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.
Container number structure
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.
Owner prefix versus operating carrier
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.
Validation and tracking
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.
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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.