An example of how a German IBAN is calculated using an account number and bank code:
For other countries, the check digits are calculated using the same method. However, the bank codes and account numbers might be mapped to different places in the IBAN. Also, the length of the IBAN differs between countries, but it is always the same within one country.
The BIC is usually looked up in a country-specific directory. For instance, German BICs are found in the quarterly-updated directory published by the German Bundesbank.