Support Guide
A practical breakdown of country checks, fixed lengths, and the MOD-97 checksum used in IBAN validation.
You do not need to leave this guide to run a structural check. Use the same validator here, then continue reading if you need more context.
The validator first reads the country code and matches it to a country-specific IBAN rule. Each supported country has a fixed length, so an IBAN with the wrong number of characters fails immediately.
This stage catches common errors such as using the wrong country code, dropping characters, or pasting a domestic account number into an IBAN field.
After the basic format passes, the IBAN is rearranged and letters are converted into numbers. The resulting number string is tested with the MOD-97 formula.
A structurally valid IBAN produces a remainder of 1. That is why checksum validation is useful for detecting single-digit mistakes and many transposed digits.
A valid checksum does not prove that the account is open, funded, owned by the intended recipient, or able to receive payments. It only shows that the format is internally consistent.
For real money movement, the recipient, bank, or payment provider still has to confirm the banking relationship.
No. Format validation is an offline structural check.
Because payment success also depends on the real account status, recipient match rules, and bank-side controls.
This tool checks format only. It validates structure and checksum, but does not confirm that a bank account exists, is active, belongs to a person, or can receive payments. It does not perform financial, identity, or bank verification.
Use the main validator when you need a fast structural check. Use support guides when you need deeper context, implementation detail, or troubleshooting help.
Open IBANWhat Is an IBAN?
Understand what an IBAN is, what each part means, and when people need one for real payments.
IBAN Format by Country
Compare IBAN lengths, example structures, and country-specific differences across major IBAN markets.
IBAN vs SWIFT/BIC
See the difference between IBAN and SWIFT/BIC, what each identifier is for, and when transfers need both.
IBAN vs Card Number
Understand why IBAN and card numbers belong to different payment systems and should never be used interchangeably.
Common IBAN Errors
See the most frequent reasons an IBAN fails validation and how to prevent bad banking data from entering your workflow.