IBAN Validator
Validate an international bank account number (IBAN): check the country code, length, and ISO 7064 MOD-97 checksum, and see it neatly formatted. Runs entirely in your browser.
Spaces are ignored. Validation covers country code, length, and the MOD-97 checksum.
- Country code
- GB
- Length check
- OK ✓
- MOD-97 checksum
- valid ✓
- Formatted
- GB82 WEST 1234 5698 7654 32
A valid IBAN is correctly structured and passes its checksum — it does not guarantee the account exists or is open. That can only be confirmed by the bank.
About this tool
An IBAN (International Bank Account Number) encodes a country, a checksum, and the domestic account details in a single standardized string defined by ISO 13616. This validator runs the three checks that prove an IBAN is well-formed: the two-letter country code must be recognized, the total length must match what that country's standard specifies (a German IBAN is always 22 characters, a French one 27, and so on), and the ISO 7064 MOD-97-10 checksum must pass. The checksum step moves the first four characters to the end, converts each letter to a two-digit number (A=10 through Z=35), and confirms the resulting integer leaves a remainder of 1 when divided by 97 — the same calculation banks use to catch transcription errors. All of this is pure arithmetic done in your browser with BigInt, so it is exact and works offline. As with any account identifier, a valid IBAN proves correct structure, not that the account actually exists.
How to use it
- Paste an IBAN (spaces are fine).
- Confirm the country code is recognized and the length is correct.
- Check that the MOD-97 checksum is valid.
- Use the neatly grouped 'Formatted' output when you need to display it.
Frequently asked questions
- What does the MOD-97 checksum actually catch?
- It reliably detects all single-digit errors and almost all transpositions and other common typing mistakes. That is why entering an IBAN with one wrong character almost always fails validation — exactly the protection it is designed to give.
- Does a valid IBAN mean the account exists?
- No. Validation confirms the IBAN is correctly structured and self-consistent. Whether the account is real, open, and able to receive funds can only be confirmed by the receiving bank, typically during a payment or an account-verification service.
- Why do IBANs have different lengths?
- Each country defines its own IBAN length and internal layout under ISO 13616, because the underlying national account-number formats differ. Norway uses 15 characters, Germany 22, France 27, Malta 31. The validator checks the length against the country code.
- How are the letters in an IBAN handled?
- For the checksum, letters are converted to numbers: A becomes 10, B becomes 11, up to Z which becomes 35. This lets the entire IBAN, including letters in the bank or branch code, be treated as one large integer for the MOD-97 calculation.
- Which countries are supported?
- The validator includes the length rules for the IBAN-registry countries across Europe, the Middle East, and beyond (60+ countries). If a country code is not recognized, it tells you rather than guessing.
- Is my IBAN sent anywhere?
- No. The check is pure in-browser BigInt math with no network request, so the account number you test is never transmitted or stored.