What Is an IBAN?
An IBAN (International Bank Account Number) is a standardised format for identifying a bank account across international borders. Originally developed in Europe, IBANs are now used in over 80 countries and are essential for making cross-border payments — particularly within the SEPA (Single Euro Payments Area) zone.
The IBAN system was created to reduce errors in international transfers and speed up processing times. Before IBANs, each country had its own account number format, leading to frequent mistakes and failed transactions.
The Structure of an IBAN
Every IBAN follows the same logical structure, regardless of country:
- Country Code (2 letters) — ISO 3166-1 alpha-2 code (e.g., GB for United Kingdom, DE for Germany)
- Check Digits (2 numbers) — used to validate the IBAN and detect errors
- BBAN (Basic Bank Account Number) — the domestic account identifier, which varies in length and format by country
A typical IBAN looks like this: GB29 NWBK 6016 1331 9268 19
Breaking that down: GB = United Kingdom, 29 = check digits, followed by the bank sort code and account number encoded in the BBAN.
IBAN Length by Country
One important thing to know is that IBAN length is not the same in every country. Here are some examples:
| Country | Code | IBAN Length | Example Format |
|---|---|---|---|
| United Kingdom | GB | 22 characters | GBkk BBBB SSSS SSCC CCCC CC |
| Germany | DE | 22 characters | DEkk BBBB BBBB CCCC CCCC CC |
| France | FR | 27 characters | FRkk BBBB BGGG GGCC CCCC CCCC CKK |
| Netherlands | NL | 18 characters | NLkk BBBB CCCC CCCC CC |
| Saudi Arabia | SA | 24 characters | SAkk BBCC CCCC CCCC CCCC CCCC |
How Check Digits Work
The two check digits in positions 3 and 4 are calculated using a MOD-97 algorithm. This mathematical check allows banks and payment systems to instantly verify whether an IBAN is valid before processing a transaction. If the check digits don't match, the IBAN is rejected — helping prevent costly errors.
You don't need to calculate check digits yourself; most online banking platforms and IBAN validators do this automatically.
Printed vs Electronic Format
IBANs are often written in two formats:
- Paper format — grouped in sets of 4 characters for readability: GB29 NWBK 6016 1331 9268 19
- Electronic format — no spaces, all uppercase: GB29NWBK60161331926819
When entering an IBAN into a banking system, always use the electronic format without spaces.
Does the US Use IBANs?
No. The United States does not use IBAN. For US dollar transfers, the standard identifiers are a routing number (ABA number) and an account number. When sending money to the US from a country that uses IBANs, you'll use the US bank's routing number and account number instead.
How to Validate an IBAN
Before sending funds, it's worth validating the IBAN you've been given. You can do this by:
- Using a free online IBAN validator
- Checking the length matches the expected length for the country
- Confirming the country code and check digits look correct
A quick validation step can save you the headache of a rejected or delayed transfer.