IBAN Format Checker

Paste any IBAN to see its country, expected length, BBAN structure, and whether the check digits are valid. Covers all 84 IBAN countries.

What Does IBAN Format Checking Actually Verify?

An IBAN format check validates three independent properties:

• Length: Every country has a fixed IBAN length defined by ISO 13616. Germany uses 22 characters, the UK 22, France 27, and so on. A wrong-length IBAN cannot be valid regardless of the other digits.
• BBAN structure: The Basic Bank Account Number (BBAN) portion follows country-specific rules — certain positions must be digits, others alphanumeric. For example, a German BBAN is 18 digits; a British BBAN starts with 4 letters (the bank identifier).
• MOD-97 check digits: Characters 3 and 4 of any IBAN are check digits computed by moving the country code to the end, converting letters to numbers, and calculating the remainder when dividing by 97. A valid IBAN must produce a remainder of exactly 1. This catches most transcription errors.

What This Checker Does Not Verify

Format validation confirms the IBAN could belong to a real account — it does not confirm that the account exists. Passing all three checks means:

• The country code is a recognised IBAN-issuing country
• The length matches the ISO 13616 specification
• The MOD-97 algorithm produces the correct remainder

For full account verification — including bank name, BIC code, and SEPA reachability — use the main IBAN checker.

Common IBAN Format Errors

• Wrong length: A German IBAN entered as 21 or 23 characters instead of 22
• Incorrect country code: "EU" or "XE" instead of a valid ISO 3166-1 code
• Transposed digits: The MOD-97 check catches most single transpositions
• Missing leading zeros: Account numbers must be zero-padded to their full field length
• Spaces included: Spaces are for readability only and are stripped before validation

Last updated: June 2026