How to track a shipping container or bill of lading by number

Updated October 22, 2026

You paid the supplier, the goods left the factory, and now you want to know where the box is. Here is the short way to find out.

Two numbers, two jobs

You will usually have one or both of these:

Container number. Four letters followed by seven digits, like CSQU3054383. It identifies one physical steel box.
Bill of lading (B/L) number. The carrier's record of your shipment. Its format changes from carrier to carrier, and many start with the carrier's own short code.

Either one works on most carrier tracking pages. If you have both, the B/L is often the safer one, because one B/L can cover more than one container.

Reading a container number

The first three letters are the owner code, which tells you which company owns the container. The fourth letter marks the type of equipment, and for regular shipping containers it is U. The next six digits are a serial number. The last digit is a check digit.

The check digit catches typos. The method, as described in the ISO 6346 references: turn each of the first ten characters into a number (digits stay as they are, letters start at A=10 and skip 11, 22 and 33), multiply each by 2 raised to its position starting at zero, add them up, divide by 11, and the remainder is the check digit. A remainder of 10 counts as 0. For CSQU305438 the sum is 6185, the remainder is 3, and the full number is CSQU3054383.

You don't need to do this by hand. It just explains why a number with one wrong digit often gets rejected.

Find the carrier

The owner code usually points to the shipping line. For example, MSCU, MSDU, MSMU and MEDU are MSC prefixes in the BIC register, and CBHU and CSNU are COSCO. Codes like COSU or ONEY start bill of lading numbers, not container numbers. Not every prefix is obvious, and some carriers share codes across brands, so treat a prefix as a strong hint, not proof. If you're unsure, your booking confirmation or B/L names the carrier.

Big lines have their own tracking pages: Maersk, MSC, CMA CGM, COSCO, Hapag-Lloyd, ONE, Evergreen, HMM, Yang Ming and ZIM. Go to the carrier's own site rather than a random lookup page, so the status comes from the source.

Steps

Copy the number exactly from your documents. Remove spaces and dashes.
Match the first four characters to the carrier.
Open that carrier's tracking page.
Choose the right field: container, B/L or booking number.
Paste and search.

If it doesn't work

Wrong field. Many sites have separate tabs for container and B/L.
Too early. A new booking may not show events until the box is gated in at the port.
Typo. Check the last digit first.
Wrong carrier. Ask your supplier or forwarder which line is carrying it.
Still nothing. Send your forwarder the number and ask for the latest event.

What the status words mean

Expect events like gate-in, loaded on vessel, departed, transshipment, arrived, discharged and available for pickup. Dates are estimates until the event actually happens, so plan around the latest update, not the first date you were given.

Next step

Tracking tells you when the goods land. Shield helps on the money side for trade businesses: a business credit card for inventory spend, US business accounts, supplier and cross-border payments, and stablecoin settlement. There are no upfront or subscription fees. Owners can live outside the US, with a US company.