🏦IBAN Validator

IBAN validator — check a bank account number online

Our free IBAN validator instantly checks a bank account number using the mod-97 algorithm in accordance with ISO 13616. Simply paste or type the number — spaces are ignored automatically. The tool identifies the country from the two-letter prefix (e.g. PL, DE, GB), verifies the number length for dozens of countries, and shows whether the check digit is valid in a fraction of a second.

If you want to check an account number before sending an international transfer or verify a counterpart's details, this IBAN validator will save you costly mistakes. Bear in mind, however, that a valid check digit does not guarantee the account is active — it only confirms that the number is mathematically consistent.

Full privacy — local processing

Verification takes place entirely in your browser — not a single character of the entered account number is sent to any server. You can use the validator even offline, and your banking data stays on your device alone.

Frequently asked questions

What is IBAN and what is it used for?

IBAN (International Bank Account Number) is an international bank account number format defined in the ISO 13616 standard. It uniquely identifies a bank account in any participating country, which is required for international SEPA and SWIFT transfers.

How does IBAN validation with the mod-97 algorithm work?

The validator moves the first four characters of the IBAN (country code and check digits) to the end of the number, converts letters to two-digit numbers (A=10, B=11, …, Z=35), then calculates the remainder when the resulting large number is divided by 97. A result of 1 means the check digit is valid. The algorithm is defined in the ISO 7064 standard.

How many digits does a Polish IBAN have?

A Polish IBAN has exactly 28 characters: the prefix PL (2 letters), two check digits, and a 26-digit domestic account number (NRB). Example format: PL61 1090 1014 0000 0712 1981 2874.

Does IBAN validation guarantee that the account exists?

No. Verification using the mod-97 algorithm only checks the mathematical validity of the check digit and the number's length. Even if an IBAN passes validation, it does not mean the account is active or belongs to a specific person. Confirming that an account exists requires contacting the bank or using SEPA Instant Credit Transfer services.

Is my data sent to a server?

No. All IBAN verification is performed locally in your browser — not a single character of the entered number reaches any server. You can validate an account number even without an internet connection.