IBAN calculator
Select the country, enter the domestic account number, and get the full IBAN with correctly computed check digits. Everything runs in your browser - what you type is never sent to a server.
We'll ask for the details the way your bank shows them.
97 countries, one standard
The complete national account string for the selected country. Spaces and dashes are fine - checked only in your browser.
From account number to IBAN
Every IBAN country defines a fixed national account format, which typically encodes the bank, sometimes a branch, and the account number itself. The IBAN simply wraps that national number with a country code and two check digits computed by the mod-97 algorithm. This calculator knows the registered format for each country, verifies your input against it, computes the check digits, and where the country defines a domestic check digit it validates that too before showing a result.
A typical example is Swiss: a domestic payment slip shows a clearing number (IID) and an account number, and the calculator combines them into the 21-character CH IBAN - zero-padding the clearing number and computing the check digits, the two steps most often botched by hand. Hungarian numbers work the same way: the 16-digit GIRO form is first extended with eight trailing zeros to 24 digits. For Hungarian accounts, the calculator recognises the bank - its name and BIC - from the account number and validates the national GIRO check digits as you type.
The output is only as good as the input: the algorithm cannot detect that you typed a wrong but structurally plausible account number. Compare the result with your bank document, and rely on your bank's Verification of Payee check before paying.
Frequently asked questions
How are the two check digits of an IBAN calculated?
The country code and "00" are appended to the domestic account number, letters are replaced by numbers (A=10 ... Z=35), and the remainder of the whole number divided by 97 is subtracted from 98. The result, padded to two digits, becomes positions 3-4 of the IBAN.
Can I convert a 16-digit Hungarian account number?
Yes. A 16-digit (8+8) Hungarian account number is extended to 24 digits by appending eight zeros, per the GIRO rule, and the HU IBAN is computed from that 24-digit form.
Is the calculated IBAN guaranteed to be my real IBAN?
It is the correct IBAN for the account number you typed, computed by the standard algorithm. If the account number itself was mistyped, the IBAN will be equally wrong, so always double-check the input against your bank statement, and confirm the payee through your bank before transferring.