Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Check an IBAN's format and mod-97 checksum.
Enter an IBAN to check its format and mod-97 checksum.
An IBAN (International Bank Account Number) identifies a bank account for international transfers, with a built-in mod-97 checksum (per ISO 7064) that catches transcription errors. This tool checks an IBAN's format and validates that checksum.
Enter an IBAN (spaces are ignored). The result shows whether it's valid, and if so, its country code.
The first 4 characters (country code + 2 check digits) are moved to the end, letters are converted to numbers (A=10, B=11, ... Z=35), and the resulting large number is checked for remainder 1 when divided by 97 -- computed digit-by-digit here since the number is far too large for standard integer arithmetic.
For validating other financial or identification number formats, see the Credit Card Validator.
Take the widely used documentation example GB29 NWBK 6016 1331 9268 19. First the tool removes spaces and converts letters to upper case. Then it moves the first four characters (GB29) to the end, giving NWBK60161331926819GB29. Each letter is replaced by two digits: N becomes 23, W becomes 32, B becomes 11, K becomes 20, G becomes 16, and so on. The resulting long number is reduced modulo 97 one digit at a time, and a valid IBAN leaves a remainder of exactly 1. Change one digit in the account portion and the remainder will almost certainly differ, which is how the tool catches typos.
The tool strips regular whitespace, upper-cases the text, and then requires two letters, two digits, and one to thirty more letters or digits. Hyphens and other punctuation are not removed, so an IBAN typed with dashes will be rejected as a format error. Lower-case input is fine. The country code shown in a valid result is simply the first two letters.
A common use is checking an IBAN copied from an invoice or an email before setting up a supplier or a standing order. Transcription mistakes, such as swapped digits or the letter O typed in place of zero, are exactly what the mod-97 test detects. Another use is testing an input form: paste a known-valid example, then alter one character and confirm your form rejects it. When paying a new beneficiary, particularly for a large amount, also confirm the details by a separate channel such as a phone call to a known number, because invoice fraud usually involves a perfectly valid IBAN that simply belongs to the wrong person.
No -- the checksum only confirms the IBAN is internally consistent (not a typo); confirming an account actually exists requires the bank's own verification systems.
No -- IBAN is widely used across Europe and many other regions, but some countries (notably the US) use different national account-numbering systems instead of IBAN.
The first 2 letters are the ISO country code (e.g. GB for the United Kingdom, DE for Germany), followed by 2 check digits, then the country-specific bank/branch/account identifier.
No. Only whitespace is stripped. Remove any dashes or dots yourself, or the tool will report a format error.
No. It accepts any length from 5 to 34 characters that passes the checksum, so also compare the length with your country's official IBAN format.
Yes. The input is converted to upper case before checking.
It is the first two letters of the IBAN. The tool shows it as a convenience but does not verify it against a list of valid countries.
Reference: MDN Web Docs