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IBAN Number

Tool to check IBAN numbers. The IBAN (International Bank Account Number) algorithm allows checking if an IBAN number is correct.

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IBAN Number -

Tag(s) : Checksum

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# IBAN Number

## IBAN number checker

Tool to check IBAN numbers. The IBAN (International Bank Account Number) algorithm allows checking if an IBAN number is correct.

### What is an IBAN?

An IBAN (International Bank Account Number) is composed of 14 to 34 characters.

It starts by 2 letters indicating the country code of the bank account, then the checksum control key (between 02 and 98) and from 10 to 30 characters depending on countries that usually identify the bank and the account number.

### How to verify an IBAN number? (Validity check)

The algorithm checks the country code first among countries accepting IBAN (ISO-13616 norm).

Example: FR for France

The algorithm starts by moving the 4 first characters (country code and checksum key) at the end of the IBAN and set the key to 00.

Example: An invented IBAN: BA51 1234 5678 90DE F123,
it becomes 1234 5678 90DE F123 BA00

Replace each letter in the IBAN by its rank in the alphabet + 9. So A=10, B=11, C=12, etc. Z=35

Example: IBAN becomes 1234567890131415123111000

Calculate the value of this big number modulo 97 and subtract the result to 98 in order to get the control key.

Example: 1234567890131415123101100 mod 97 = 47 and 98-47 = 51. The checksum key is 51.

Check if the two 2 characters after the country code are 51, if yes the IBAN is valid.

Furthermore, you need to check if bank code and account number actually exist, and this is not possible using the algorithm only.

The corresponding regular expression (which is not sufficient) is : [A-Z]{2}[0-9]{2}[A-Z0-9 ]{10,35}

### A form is asking me more characters, what to do?

Sometimes it is asked to concatenate both IBAN and BIC codes (IBAN+BIC or BIC+IBAN).