IBAN Validator
Validate an IBAN with the official mod-97 checksum, verify the country specific length and format, and split it into bank code, branch code and account number.
Last reviewed by the Radiatus Cloud team
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An IBAN is self checking
The International Bank Account Number was designed so that a typo can be caught before a payment is submitted rather than after it has been sent to the wrong bank. Two check digits sit in positions three and four, computed with a mod-97 operation over the rest of the number. Any single character error, and the overwhelming majority of transposed pairs, changes the remainder and fails validation. Checking an IBAN before submitting a transfer costs nothing and avoids a recall process that can take weeks.
Length is country specific
The checksum alone is not enough. Every country registered with SWIFT declares a fixed IBAN length and an internal structure, so a Norwegian IBAN is fifteen characters and a Maltese one is thirty one. A number that passes mod-97 but has the wrong length for its country prefix is invalid, and this is the most common failure for a hand typed account number where a digit was dropped. The validator checks the declared length for the two letter country code before it checks the arithmetic.
What validation does and does not prove
A valid IBAN is structurally correct. It does not prove the account exists, that it is open, or that it belongs to the person you intend to pay. Only the receiving bank can confirm that. Validation catches typing errors, which is the class of problem it was designed for, and nothing beyond that.
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Frequently Asked Questions
How does the mod-97 check work?
The first four characters are moved to the end, each letter is replaced by a number where A is 10 through Z is 35, and the resulting large integer is divided by 97. A valid IBAN leaves a remainder of exactly 1. The tool shows the remainder it computed.
Does a valid IBAN mean the account exists?
No. It means the number is well formed and free of typing errors. Whether the account is open and belongs to the intended recipient can only be confirmed by the bank, usually through a confirmation of payee service.
Why does my IBAN fail on length?
Each country has a fixed IBAN length registered with SWIFT. A missing or extra character fails that check before the checksum is even considered. The tool shows the expected length for the country code you entered.
Should I store IBANs with spaces?
Store them without spaces, in upper case. Spaces in groups of four are a display convention for printing and reading aloud; systems that compare IBANs should compare the compact form.
Is my IBAN sent anywhere?
No. The arithmetic runs in your browser and nothing is transmitted. That matters for a bank account number, which is exactly the kind of value that should not be pasted into a remote service.
Privacy & Security
Everything runs in your browser; nothing is uploaded.
How to Use
Paste an IBAN to check its checksum, length and national structure.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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