What an IBAN Is

IBAN stands for International Bank Account Number. It is an international standard (ISO 13616) that writes an account number in a fixed format so payments can be checked before they are sent. Every IBAN has the same three parts:

• A two-letter country code, such as GB for the United Kingdom or DE for Germany.
• Two check digits, calculated from the rest of the IBAN to catch typing mistakes.
• The BBAN (basic bank account number), which holds the bank identifier and the account number in the format each country uses. Its length and mix of letters and digits differ by country.

IBANs range from 15 characters (Norway) to 33 characters (Russia) across the registry.

How an IBAN Is Validated

1. Length. Each country has one fixed IBAN length.
2. Format. Each position must be a digit, a letter, or either, as the country's format requires.
3. Check digits (MOD 97). Move the first four characters to the end, replace each letter with a number (A is 10, B is 11, up to Z at 35), and divide the resulting number by 97. A valid IBAN leaves a remainder of 1.

Open "Show the working" in a result to see each step for your IBAN. The MOD 97 check catches every single-digit typo and almost all swapped digits, but it cannot tell whether the account is real.

How the Builder Works

Choose a country and the builder shows one box for each part of that country's format, such as the sort code and account number for the United Kingdom. Once every box is filled in, it works out the two check digits and puts the IBAN together. It labels the parts for well-known countries and shows the format for the rest.

• It calculates the IBAN check digits only. It cannot confirm that the bank identifier or account number is real.
• Several countries build their own national check digits into the account number, for example France, Spain, Italy and Belgium. Enter these as they appear in your domestic account details. The builder does not check them.
• For a UK IBAN, the four-letter bank identifier is not the sort code. It comes from the bank, so take it from your bank's documents or ask the bank for your IBAN.

IBAN Length and Format by Country

The table shows every country in the registry data we use, with the total length of its IBAN and the format of the part after the check digits. "Digits" means 0 to 9, "letters" means A to Z, and "letters or digits" means either.

Countries That Do Not Use IBAN

Many countries are not in the registry, including the United States, Canada, Australia, India, Japan, China, South Africa, Ghana, Kenya and Nigeria. They identify accounts in other ways. Nigerian accounts use a 10-digit NUBAN (see our NUBAN validator), and international payers usually need the account number, the bank name and the bank's SWIFT/BIC code, which you can find with our Nigeria SWIFT code finder.

For other systems, see our US ABA routing number checker, Canadian transit number lookup, Indian IFSC checker and Australian BSB checker.

The Data This Tool Uses

The country formats come from the SWIFT IBAN Registry, which is the official ISO 13616 registry. We used the registry's 89-country data as published in open-source libraries (python-stdnum's data file, generated from registry release 101, cross-checked against php-iban). We could not download the file from swift.com directly, so a newer release may add or change a country. The official registry is at swift.com. We tested the tool against the registry's example IBAN for every country, and all 89 validate. We last checked on 18 September 2026.

Frequently Asked Questions