IBAN Calculator & Validator

Build an IBAN from bank code and account number, or validate an IBAN — including BIC, bank name and check digit.

{{ __t('examples_label') }} {{ ex.label }}
{{ checkResult.valid ? __t('result_valid') : __t('result_invalid') }}
{{ checkResult.formatted }}
{{ __t('check_structure') }}
{{ __t('check_length') }}
{{ __t('check_mod97') }}
{{ __t('check_country_unknown') }}
{{ __t('meta_bank') }}
{{ checkResult.de.bankName || __t('meta_unknown') }}
{{ __t('meta_blz') }}
{{ checkResult.de.blz }}
{{ __t('meta_konto') }}
{{ checkResult.de.konto }}
{{ __t('check_account') }}
{{ __t('make_girocode') }}

{{ __t('privacy_note') }}

What does the IBAN calculator and validator do?

This tool builds the matching IBAN from a German bank code (Bankleitzahl) and account number, or validates an existing IBAN. For German IBANs it additionally resolves the BIC, bank name and city, and checks the account number's check digit.

Validation works for IBANs from more than 120 countries: format, length and the international modulo-97 checksum are checked. Bank name and BIC are resolved for German bank codes from the official Deutsche Bundesbank file.

How is an IBAN structured?

An IBAN (International Bank Account Number) is standardized by ISO 13616 and, in Germany, 22 characters long. It consists of several parts:

  • Country code — two letters, e.g. DE for Germany
  • Check digits — two digits, computed via modulo 97
  • Bank code — eight digits in Germany, identifying the bank
  • Account number — up to ten digits, left-padded with zeros

Build an IBAN from bank code and account number

A German IBAN is formed by concatenating the bank code and the account number padded to ten digits. From this the tool computes the two-digit check number using modulo 97 and prepends DE.

Note: for most banks this standard computation yields the correct IBAN. A few institutions use special Bundesbank IBAN rules that re-map the account or bank code. In those cases you should verify the computed IBAN against your bank statement.

Validating an IBAN — how does it work?

To validate, the IBAN is turned into a number per ISO 7064: the first four characters move to the end, letters are replaced by numbers, and the result must leave a remainder of 1 when divided by 97. If it does not, the IBAN contains a typo or transmission error.

For German IBANs the tool additionally checks the account number's check digit. The Deutsche Bundesbank defines about 150 calculation methods that differ per bank — the tool automatically applies the correct method for each bank code.

Find BIC and bank name for an IBAN

The BIC (Business Identifier Code, also called SWIFT code) identifies a bank internationally. For German IBANs the tool reads the BIC, bank name and city directly from the official Deutsche Bundesbank bank code file, which is updated quarterly.

Frequently asked questions

Can I find the BIC for every IBAN?
BIC and bank name are resolved here for German IBANs from the Bundesbank file. For IBANs from other countries the tool checks format, length and checksum, but cannot show a bank name because no official German data source exists for that.
Does a valid IBAN mean the account really exists?
No. Only structure, length and check digits are verified. Whether an account actually exists or belongs to a named holder cannot be derived from this — only the account-holding bank knows that.
Are my bank details stored?
No. The IBAN is sent to the CalcSI server only for the check, processed there, and not stored or shared with third parties.
What is the account check digit?
German account numbers contain a check digit that detects typos. Which calculation method applies depends on the bank. The tool applies the method the Bundesbank assigns to each bank code.
Can I create a GiroCode directly from the IBAN?
Yes. After a successful check or calculation, clicking Create GiroCode takes you straight to the QR code generator with the IBAN already prefilled — ideal for invoices and donations.

Related tools on CalcSI

Data source: official Deutsche Bundesbank bank code file. All information without warranty; for banks with special rules the computed IBAN may differ.