The check digit is a single-digit verification value used to catch typing errors in a container number. It is derived mathematically from the first 10 characters of the number; if even a single character is mistyped, the verification fails.
From A=10 to Z=38; multiples of 11 (11, 22, 33) are skipped — so no letter value creates ambiguity in mod 11.
Each character is multiplied by a weight based on its position: 2⁰, 2¹, 2²… 2⁹ (from 1 to 512).
The sum of the products is divided by 11; the remainder is the check digit.
If the remainder is 10, the check digit is written as 0. Since this shares the same digit as a remainder of 0, it is recommended in practice to avoid such serial numbers.
MSCU 654321 0
Owner code (3 letters registered with BIC) · category (U: freight container, J: detachable equipment, Z: trailer/chassis) · 6-digit serial number · check digit.
First check the number against the plate letter by letter — the most common cause is a typing error (such as mixing up 0/O or 1/I). If the number on the plate is the same and verification still fails, a professional inspection of the CSC plate and the container’s identification is recommended.
The mathematical verification still works; however, for international transport the owner code must be registered with BIC (Bureau International des Containers). This tool only verifies the check digit; it does not look up BIC registration.
It is completely free, and the calculation runs on your device, inside your browser — the number you enter is never sent to any server and is not stored.
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