IBAN validator

How an IBAN is built

An International Bank Account Number has three parts: a two-letter country code, two check digits, and the domestic account number (BBAN), whose length and layout are fixed per country. A German IBAN has 22 characters, a British one 22, a Brazilian one 29. Banks in Europe, the Middle East, parts of Africa and Latin America use IBANs for cross-border and often domestic transfers.

The check digits make almost every typo detectable: change one character or swap two, and the checksum fails.

Worked example

GB82 WEST 1234 5698 7654 32: move GB82 to the end, turn the letters into numbers (G = 16, B = 11, W = 32, E = 14, S = 28, T = 29) and divide the resulting long number by 97. The remainder is 1, so the IBAN is valid. With GB83 instead, the remainder is 2 and validation fails.

Limits

A valid IBAN is well-formed, not necessarily an open account. Always confirm details with the recipient.

The page removes spaces, checks the general shape (two letters, two digits, then letters and digits), compares the length with the SWIFT IBAN Registry for that country, and verifies the check digits with ISO 7064 MOD 97-10: the first four characters are moved to the end, letters become two-digit numbers, and the remainder of division by 97 must be 1. It computes the remainder digit by digit, so no precision is lost. The country name is shown in your language. Nothing is sent anywhere.