HesapHanem

IBAN Validator

Is my IBAN valid?

How it is calculated

The validator runs three steps. First it removes spaces and converts letters to upper case. Then it reads the first two letters as the country code and compares the total length with the length listed for that country (for example 22 for the UK, 22 for Germany, 26 for Turkey); unknown countries are reported as unknown and fail. Finally it applies the mod 97 test: the first four characters are moved to the end, each letter is replaced by a number (A = 10 … Z = 35), and the long number must leave a remainder of exactly 1 when divided by 97. Only letters and digits are allowed, so hyphens or dots make the check fail. A pass means the IBAN is correctly formed, not that the account exists or belongs to the named person.

Worked example

Enter GB82 WEST 1234 5698 7654 32. After removing spaces the tool counts 22 characters, matching the 22 expected for country GB, so the length line reads 22 / 22. It then moves GB82 to the end, turns the letters into numbers and divides the resulting number by 97. The remainder is 1, so the status is Valid and the country shows GB.

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Common mistakes

  • Assuming a valid result proves the account exists or belongs to the payee; only the format and check digits are tested.
  • Typing the letter O instead of the digit 0 (or I instead of 1) when copying by hand.
  • Pasting an account number or BIC/SWIFT code instead of the full IBAN.
  • Leaving hyphens, dots or other symbols in the text; only letters and digits are accepted (spaces are fine).
  • Expecting a country that is not in the tool's list to pass; it shows an unknown country and fails.

About this calculator

This tool checks whether an IBAN (International Bank Account Number) is structurally valid by verifying its length against the issuing country's format and running the mod-97 checksum defined in the ISO 13616 standard — the same check-digit algorithm banks use internally to catch typos before a transfer is submitted.

It's used before sending or receiving an international wire transfer, since a single mistyped digit in an IBAN can send money to the wrong account or get a payment rejected outright. Freelancers invoicing foreign clients, accountants processing supplier payments, and anyone entering payroll or vendor bank details double-check the IBAN here first, because catching an error before submission is far easier than chasing down a failed or misdirected transfer afterward.

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Comments (1)

  • Editorial team

    A Valid status here means the length and the check digits are consistent. It does not prove the account exists, is open, or belongs to the person you intend to pay. Before the first large transfer to a new payee, confirm the account holder's name through an invoice or a phone call you place yourself. Spaces, as printed on statements, are fine. If a real IBAN from your country is reported as unknown, post its first two letters and its length.

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