- What is an IBAN?
- An IBAN (International Bank Account Number) is a standardized format for identifying bank accounts internationally. Defined by ISO 13616 and maintained by SWIFT, it contains a 2-letter country code (e.g. DE for Germany, GB for the United Kingdom), 2 check digits, and a country-specific domestic account number called the BBAN (Basic Bank Account Number). Over 80 countries use the IBAN system for cross-border payments, and it is mandatory for all SEPA transfers within the European Economic Area. If you need to validate a US bank number instead, try our routing number validator, or use our sort code validator for UK banks.
- How does IBAN validation work?
- IBAN validation uses the MOD-97 algorithm defined in ISO 7064. The process works in 4 steps: (1) move the first 4 characters (country code + check digits) to the end, (2) convert all letters to numbers where A=10, B=11, through Z=35, (3) compute the remainder when dividing the resulting number by 97, (4) if the remainder is exactly 1, the IBAN is valid. This algorithm catches over 99% of transcription errors, including single-character mistakes and transposed digits. BankCheck also validates the country-specific BBAN length and structure for each of the 40+ supported countries.
- How long is an IBAN?
- IBAN length varies by country and is always fixed for a given country. Examples: Norway has the shortest at 15 characters, Belgium is 16, the Netherlands and Denmark are 18, Austria and Luxembourg are 20, Germany and the United Kingdom are 22, Czech Republic, Spain, Sweden, and Romania are 24, Portugal, France, Italy, and Greece are 27. The length check is the first validation step — an IBAN with the wrong number of characters is immediately rejected.
- Where can I find my IBAN?
- Your IBAN is typically printed on your bank statement, shown in your online banking portal, or printed on your debit or credit card. You can also ask your bank directly or use your bank’s mobile app. In many European countries, your IBAN is derived directly from your existing domestic account number by prepending the country code and check digits. For example, a German IBAN combines ‘DE’ + 2 check digits + an 8-digit bank code (Bankleitzahl) + a 10-digit account number.