IBAN validator & calculator
Instantly check whether an IBAN is correct, or work out the two check digits of a Spanish IBAN from the account's 20 digits. Everything is verified in your browser, without sending the number to any server.
You can type it with or without spaces. Works with IBANs from any country.
How an IBAN is validated
An IBAN includes two check digits after the country code that make it possible to detect typing errors. The check is the mod-97 algorithm: the first four characters are moved to the end, the letters are replaced by numbers (A=10, B=11…) and the resulting number must give a remainder of 1 when divided by 97.
A Spanish IBAN has 24 characters: "ES", two check digits and the 20 digits of the traditional account number (bank, branch, internal check digits and account number). This tool validates the mathematical structure of the IBAN, but it does not check whether the account actually exists at the bank.