How is a container number built up?
The number has four parts:
- Owner code. Three capital letters that identify the owner or the principal operator, such as BIC in the example.
- Equipment category identifier. One capital letter. U stands for a container. J stands for detachable equipment belonging to a container. Z stands for trailers and chassis. For ordinary containers it is therefore a U.
- Serial number. Six digits. The owner decides which digits to use.
- Check digit. One digit, often written in a box. It helps to see whether the number has been copied or read correctly.
The owner code and the category letter are often mentioned together. BICU is then the owner's "BIC code".
Who issues owner codes?
The Bureau International des Containers (BIC) keeps the international register of owner codes. BIC has published this register since 1970. The owner code is therefore unique: no two owners have the same code. If you see a code on a container that you do not know, you can look up the owner in the BIC register.
How do you calculate the check digit?
The check digit follows from the first ten characters. The calculation works like this:
- Give each character a value. Digits keep their own value. Letters start at A = 10 and count up. Multiples of 11 (11, 22 and 33) are skipped. So A = 10, B = 12, C = 13, and so on up to Z = 38.
- Multiply the value of each character by a weight. The first character gets 2 to the power of 0 (that is 1), the second 2 to the power of 1 (that is 2), the third 4, the fourth 8, and so on up to 512 for the tenth character.
- Add up all the results.
- Divide the sum by 11 and take the remainder.
- If the remainder is 10, the check digit is 0. Otherwise the remainder is the check digit.
An example
Take BICU 123456. This is the example that BIC itself uses.
| Character | Value | Weight | Result |
|---|---|---|---|
| B | 12 | 1 | 12 |
| I | 19 | 2 | 38 |
| C | 13 | 4 | 52 |
| U | 32 | 8 | 256 |
| 1 | 1 | 16 | 16 |
| 2 | 2 | 32 | 64 |
| 3 | 3 | 64 | 192 |
| 4 | 4 | 128 | 512 |
| 5 | 5 | 256 | 1280 |
| 6 | 6 | 512 | 3072 |
The sum is 5494. Divide by 11: 11 × 499 = 5489, the remainder is 5. The check digit is therefore 5 and the full number is BICU 123456 5.
If the owner code changes, for example when a container gets a new owner and is marked again, the check digit changes too. The digit depends on both the code and the serial number.
The size & type code
Besides the number, a container also shows the size & type code, such as 22G1 or 45G1. That code is in the same standard (ISO 6346); the tables are published by BIC. The first character gives the length, the second the height (and sometimes the width), and the last two characters give the container type and its version. For 22G1 the length is 20 feet, the height 8 feet 6 inches (2591 mm) and the type general purpose (G1). For 45G1 the length is 40 feet and the height 9 feet 6 inches (2896 mm), a "high cube", also of the general purpose type.
What do we do with this?
We supply BIC codes and size & type codes as stickers for containers. For the container sets, our form calculates the check digit for you as soon as you fill in the owner code and the serial number. For the separate BIC codes and size & type codes you fill in the code you need yourself; there we do not check the digit automatically. If your code is not listed, state it in your request.
Frequently asked questions
What does the letter U in a container number mean?
U is the equipment category identifier and stands for a container. J stands for detachable equipment belonging to a container, Z for trailers and chassis.
Must the check digit be in a box?
The check digit is usually written in a box, so that it stands out clearly from the serial number. Our form for container sets puts it in a box.
Who decides my owner code?
BIC keeps the register of owner codes. A code you make up yourself may already belong to someone else.
Questions about this text? Email info@kuyper-graveertechniek.com or call 010 216 2344.
