ISO 6346 · Free browser tool

Container number checker

Validate a container number or calculate its missing check digit. Decode the owner code, equipment category and serial number without a sign-up.

Enter 11 characters to validate, or the first 10 to calculate the final digit. Spaces and hyphens are accepted.

Your format and check-digit result will appear here.

This check runs in your browser. The tool does not send or store the entered number.

How a container number is structured

An ISO 6346 identifier combines three owner-code letters, one equipment-category letter, six serial digits and a final check digit. The check digit helps detect entry and transmission errors.

The calculation weights the first 10 characters by successive powers of two and takes the remainder modulo 11; a remainder of 10 becomes 0. A matching digit does not guarantee that every other character was entered correctly.

BIC identification reference ↗Track a shipment →Browse carrier SCAC codes →

Container number questions

What does a valid container check digit prove?

It confirms that the identifier has the expected format and that its final digit matches the ISO 6346 calculation. It does not verify owner registration, a physical container, an active shipment or tracking availability.

Can I calculate a missing check digit?

Yes. Enter the first 10 characters: three owner-code letters, one equipment-category letter and six serial digits. The checker calculates the eleventh character. Confirm the complete identifier against the equipment marking or shipping document before use.

What do U, J and Z mean?

U identifies freight containers, J identifies detachable freight-container-related equipment, and Z identifies trailers and chassis. These are equipment categories, not carrier SCAC codes.

Does an owner prefix identify the carrier carrying my shipment?

Not necessarily. Equipment can belong to a leasing company or another owner. The three-letter owner code and equipment category do not establish which shipping line is currently carrying it. This tool does not look up owners or carriers.