Check an IBAN before a transfer
Quickly verify MOD 97 checksum consistency before copying an IBAN into a payment instruction.
Finance & business
IBAN validator
Locally validate the general structure and MOD 97 checksum of an IBAN, or calculate check digits from a country code and BBAN.
You can enter the IBAN with or without spaces.
Enter the BBAN without the country code or check digits.
- Country
- Check digits
The check verifies the general structure and MOD 97 checksum. It does not confirm that the account exists, identify its owner, or validate every country-specific rule.
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How does this tool work?
An IBAN contains a country code, two check digits and a BBAN. This tool validates the checksum or calculates it locally without sending bank details to a server.
To validate an IBAN, the tool normalizes the input, moves the first four characters to the end, converts letters into numbers, and applies the MOD 97 checksum. To calculate check digits, it combines the BBAN with the country code and 00, computes the modulo 97 remainder, and derives the two check digits. This mathematical validation checks checksum consistency only; it does not confirm that the account exists or identify its owner.
How to use this tool
Choose an action
Validate an existing IBAN or calculate its two check digits.
Enter the data
Paste the IBAN, or provide the country code and BBAN.
Read the result
The tool shows the formatted IBAN and the MOD 97 result.
Use cases
Check manual data entry
Spot common typing errors when entering or copying an IBAN from a document or message.
Calculate check digits
Generate the two check digits from a country code and BBAN for testing or constructing an IBAN.
Tips and best practices
- Spaces and hyphens are ignored during validation.
- A valid checksum does not prove that the bank account exists.
- All data stays in your browser.
Frequently asked questions
Does a valid IBAN checksum prove the account exists?
No. The mathematical check validates the checksum only, not the existence or ownership of the account.
Are my bank details sent anywhere?
No. The calculation runs locally in your browser.
How does the MOD 97 check work?
The IBAN is rearranged, letters are converted to numbers, and the resulting sequence is reduced modulo 97. A valid IBAN is expected to leave a remainder of 1.
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