Container number check (ISO 6346)
Enter the container number from the bill of lading, booking or declaration and see at once whether the check digit is right, who owns the container and what its size and type code means. Everything is calculated in your browser.
Common size and type codes
| Code | Meaning |
|---|---|
| 22G1 | 20′ general purpose, standard height |
| 42G1 | 40′ general purpose, standard height |
| 45G1 | 40′ High Cube general purpose |
| 22R1 | 20′ reefer |
| 45R1 | 40′ High Cube reefer |
| 22U1 | 20′ open top |
| 42P1 | 40′ flat rack |
| 22T1 | 20′ tank container |
| L5G1 | 45′ High Cube general purpose |
How the check digit is calculated
Each of the first ten characters is converted to a number: digits keep their value, letters get values from 10 (A) to 38 (Z), skipping 11, 22 and 33. Each value is multiplied by 2 raised to the power of its position (1, 2, 4, 8 … 512), the products are added up, and the remainder of dividing the sum by 11 gives the check digit (a remainder of 10 counts as 0).
This is why a single wrong or swapped character almost always produces a different check digit — and why the check catches most typos in bills of lading, customs declarations and collection orders.
We move groupage from Europe in containers through our warehouse in Rotterdam, and full containers (FCL 20′ and 40′) directly from the port.
Sea freight services
Frequently asked questions
How is a container number structured?
Under ISO 6346 the number has 11 characters: three letters for the owner code (registered with the Bureau International des Containers, BIC), a fourth letter for the category (U for freight containers), a six-digit serial number and a final check digit. For example, CSQU 305438 3.
What is the check digit and why check it?
The check digit is calculated from the first ten characters using the ISO 6346 formula. If one digit is wrong or two are swapped, the check digit no longer matches. A wrong container number in the bill of lading, declaration or collection order is a common cause of port delays and discrepancies during customs clearance.
How can I find the owner of a container?
The first three letters are the owner code. We show the owner for the largest lines (MSC, Maersk, CMA CGM, Hapag-Lloyd, COSCO, Evergreen, ONE and others) and leasing companies. The full register is kept by BIC (bic-code.org). Note that a container owned by a leasing company can be used by any line.
What does a size and type code such as 45G1 mean?
It is the ISO code printed on the container next to the number. The first character is the length (2 – 20 ft, 4 – 40 ft, L – 45 ft), the second the height (2 – standard 8′6″, 5 – High Cube 9′6″), the letter the type (G – general purpose, R – reefer, U – open top, P – flat rack, T – tank). 45G1 is a 40 ft High Cube general-purpose container.
Can I track a container by its number?
Tracking is provided by the line that issued the bill of lading: enter the number on its website. If the container carries our cargo (LCL groupage or FCL via Rotterdam), its status is available in our tracking by the shipment code.
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