About container number validator


As long as manual data entry has its place in the transport industry, there is room for a human error.

The last digit of a container number, the check digit, helps to check integrity of the container number and detect possible errors. This container number validator tool lets you quickly check container numbers for errors. Using this tool, only takes a quick moment.

To use our calculator, enter first 10 characters of the container number (4 letters and 6 digits) and press “submit”. The Check Digit that will appear below should be your 11th character.

If different from the last character of your container number, then container number is invalid

The formula to check if a container number is correct is called the ISO 6346 standard. The container number, also known as the container's serial number or ISO number, consists of four components:


  1. Prefix: The three-letter prefix represents the owner or operator of the container. It is registered and assigned by the Bureau International des Containers (BIC). Examples include MSC, CMA, MAE, and TGH.


  1. Category Identifier: The fourth character represents the category identifier, which specifies the type and size of the container. It can be a letter or a number.


  1. Serial Number: The six-digit serial number uniquely identifies the individual container within the owner's fleet.


  1. Check Digit: The last character is the check digit, which is calculated using a specific algorithm. It helps verify the accuracy of the container number and detect any errors.


To validate a container number using the check digit, follow these steps:


  1. Assign a numerical value to each letter in the container number according to their position in the English alphabet (A=10, B=12, C=13, and so on).


  1. Multiply each digit of the container number (excluding the check digit) by its assigned weight factor based on its position:

- For the first 10 digits (letters and numbers), use weights 1, 2, 4, 8, 16, 32, 64, 128, 256, 512.

- For the 11th digit, use a weight of 1.


  1. Sum the products obtained from step 2.


  1. Divide the sum by 11.


  1. The remainder of the division should be the same as the check digit. If the remainder is 10, the check digit should be represented as "0".


By applying this formula, you can verify the accuracy of a container number and ensure it follows the ISO 6346 standard.