What is an IBAN?
An IBAN is the international bank account number format with a built-in checksum. Learn its structure and validate an IBAN free.
An IBAN (International Bank Account Number) is a standardized way to identify a bank account across borders. It starts with a two-letter country code and two check digits, followed by the country’s own account identifier — up to 34 characters total.
The structure
IBAN = country code (2 letters) + check digits (2) + BBAN (the national bank and account number, variable length per country). For example a German IBAN is 22 characters; a Ukrainian one is 29. The two check digits are computed with a mod-97 formula over the rearranged string.
The mod-97 checksum
To validate, move the first four characters to the end, convert letters to numbers (A=10 … Z=35), and take the whole thing mod 97. A valid IBAN yields 1. This catches almost all typos and transposed characters before a payment is ever attempted.
What it does not tell you
A structurally valid IBAN is not necessarily an open, active account. It only confirms the format and checksum are correct — useful to reject typos on a form instantly.
Try it now — free, no signup
Use the IBAN validator in your browser. Then, when you need it at scale with an API key and higher limits, grab the full Eveses API.