IBAN Validator
Check if an IBAN passes the mod-97 checksum.
Assumptions used in this calculation
- Format check only: This only checks the checksum format, it does not verify the account exists or is active.
About this calculator
International bank transfers fail or bounce back surprisingly often because of a single mistyped character in a long IBAN, and catching that error before submitting a payment saves time and, in some cases, transfer fees. This validator takes an IBAN, rearranges it by moving the first four characters to the end, converts each letter to its corresponding two-digit number per ISO 7064, and checks whether the resulting large number is congruent to 1 modulo 97, while also reading the leading two letters to identify the issuing country. Performing a mod-97 calculation on a 30+ digit number by hand is impractical without long division software, and getting the letter-to-number conversion or rearrangement wrong invalidates the whole check. The calculator runs this instantly, giving a clear valid/invalid result so you can catch a typo before it delays or fails a wire transfer.
Worked example
GB29 NWBK 6016 1331 9268 19
Result: Valid IBAN
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