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IBAN Validator

Check whether an IBAN (International Bank Account Number) is valid — instantly, in your browser, free of charge.

How the check works

Every IBAN ends with a built-in checksum based on the MOD-97 algorithm defined in ISO 7064. To verify it, the first four characters (country code and check digits) are moved to the end of the IBAN, and every letter is replaced with a number (A=10, B=11, ... Z=35).

The resulting long number is then divided by 97. If the remainder is exactly 1, the checksum is correct and the IBAN is structurally valid. This catches almost all typos, such as swapped or mistyped digits — without needing to contact a bank.

Frequently asked questions

Does a valid IBAN mean the account exists?
No. This check only verifies the IBAN's checksum and format. It confirms the number is well-formed, not that the account is open or belongs to a specific person.
Is my IBAN sent to a server?
No. The check runs entirely in your browser — nothing is transmitted or stored.
Why does the country code matter?
The first two letters identify the country that issued the account, which also determines the IBAN's expected length and structure.
What does the checksum actually protect against?
It reliably detects common input mistakes like transposed or mistyped digits, so most typos are caught immediately instead of causing a failed transfer.
How many digits does an IBAN have?
It depends on the country. An IBAN can be between 15 and 34 characters long, and each country has its own fixed length. A German IBAN, for example, always has exactly 22 characters, while an Austrian one has 20.
How is an IBAN structured?
Every IBAN starts with a two-letter country code, followed by two check digits, and then the country-specific part (the BBAN). In Germany the BBAN is the 8-digit bank code (Bankleitzahl) followed by the 10-digit account number.
Where are the account number and bank code inside the IBAN?
In a German IBAN, after the four-character prefix (country code plus check digits), the next 8 digits are the bank code (Bankleitzahl) and the final 10 digits are the account number. This tool extracts the bank code automatically and, for German and Austrian IBANs, also shows the bank name and location.
Why does an IBAN contain letters?
The first two characters are always letters — the country code, such as DE or AT. Some countries also include letters in their account identifier. For the checksum, every letter is converted to a number (A=10, B=11, … Z=35) using the MOD-97 algorithm.

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