The International Bank Account Number (IBAN) was created to make cross-border payments faster and reduce errors. Instead of every country writing account numbers differently, an IBAN wraps the national account details in a standard frame, with a country code at the front and two check digits that let banks detect typos before money is sent. It is defined in the ISO 13616 standard, and SWIFT maintains the official registry of national formats. Our IBAN validator checks the length, structure and check digits of any IBAN instantly.
Structure of an IBAN
Every IBAN has the same three parts:
| Part | Length | Example (UK) |
|---|---|---|
| Country code (ISO 3166) | 2 letters | GB |
| Check digits | 2 digits | 29 |
| BBAN (Basic Bank Account Number) | up to 30 characters, fixed per country | NWBK 6016 1331 9268 19 |
The BBAN contains the national bank and account identifiers. In the UK it is a four-letter bank code (from the BIC), the six-digit sort code and the eight-digit account number.
IBANs are written electronically without spaces, and on paper in groups of four for readability: GB29 NWBK 6016 1331 9268 19.
IBAN length by country
The length is fixed for each country, which is the first thing a validator checks.
| Country | Length | Example format |
|---|---|---|
| Norway | 15 | NO93 8601 1117 947 |
| Belgium | 16 | BE68 5390 0754 7034 |
| Netherlands | 18 | NL91 ABNA 0417 1643 00 |
| United Kingdom | 22 | GB29 NWBK 6016 1331 9268 19 |
| Ireland | 22 | IE29 AIBK 9311 5212 3456 78 |
| Germany | 22 | DE89 3704 0044 0532 0130 00 |
| United Arab Emirates | 23 | AE07 0331 2345 6789 0123 456 |
| Spain | 24 | ES91 2100 0418 4502 0005 1332 |
| Saudi Arabia | 24 | SA03 8000 0000 6080 1016 7519 |
| Türkiye | 26 | TR33 0006 1005 1978 6457 8413 26 |
| France | 27 | FR14 2004 1010 0505 0001 3M02 606 |
| Italy | 27 | IT60 X054 2811 1010 0000 0123 456 |
These examples follow the published sample formats and are not real accounts. Around 90 countries and territories use IBAN, including all of the EU and EEA, the UK, Switzerland, much of the Middle East and parts of Africa and Latin America.
Countries that don’t use IBAN
Several major economies do not use IBAN for domestic accounts:
- United States: a nine-digit ABA routing number identifies the bank, plus a separate account number. International wires need the bank’s SWIFT/BIC code.
- Canada: transit number, institution number and account number.
- Australia: a six-digit BSB plus account number.
- China, India, Japan: national account formats with SWIFT for international payments (India uses the IFSC code domestically).
- Russia: a 20-digit account number plus the bank’s 9-digit BIK code; no IBAN.
If you send money from Europe to these countries, your bank will ask for the account number and SWIFT/BIC instead.
How the check digits work (mod 97)
The two check digits make an IBAN self-validating. The algorithm, from ISO 7064, is:
- Move the first four characters (country code and check digits) to the end.
- Replace each letter with two digits: A = 10, B = 11, … Z = 35.
- Treat the result as a large integer and divide by 97.
- If the remainder is 1, the IBAN is valid.
Example with GB29 NWBK 6016 1331 9268 19:
- Rearranged:
NWBK60161331926819GB29 - Letters replaced: N = 23, W = 32, B = 11, K = 20, G = 16, B = 11
- Number:
2332112060161331926819161129 - 2332112060161331926819161129 mod 97 = 1 → valid
This catches all single-character errors and almost all swapped adjacent characters. It does not prove that the account exists or belongs to the person you think; it only proves the number is well formed.
IBAN vs SWIFT/BIC
| IBAN | SWIFT/BIC | |
|---|---|---|
| Identifies | A specific account | A bank (and optionally a branch) |
| Length | 15–34 characters | 8 or 11 characters |
| Example | GB29 NWBK 6016 1331 9268 19 | NWBKGB2L |
| Needed for | SEPA and most international payments to IBAN countries | Many international wires, especially outside SEPA |
Within the SEPA zone (EU, EEA, UK, Switzerland and a few others), euro payments need only the IBAN. Banks must not require a BIC for SEPA payments.
Safety tips
- Check the name. UK banks run Confirmation of Payee, which checks that the name matches the account before you pay. The EU has introduced a similar Verification of Payee service for euro transfers. Take any “no match” warning seriously.
- Beware of changed bank details. Invoice-redirection fraud often arrives as an email saying a supplier’s IBAN has changed. Always confirm by phone using a number you already have.
- Don’t trust a valid checksum alone. A fraudster’s IBAN is just as valid as a real supplier’s.
- Share your IBAN sensibly. It is meant to be given out for receiving payments, but keep an eye on unexpected direct debits.
Common mistakes
- Confusing the letter O with zero, or I with 1 (IBANs use capital letters; validators catch most of these).
- Copying an IBAN with a missing group of digits.
- Using an IBAN for a US or Australian account, which do not have one.
- Entering a domestic account number in the IBAN field.
Checklist
- Check the country code and the length for that country.
- Validate the mod-97 check digits with a validator.
- Add the SWIFT/BIC when your bank asks for it.
- Confirm the account holder name (Confirmation or Verification of Payee).
- Verify any change of bank details by phone.
Paying in another currency? Our exchange rates guide explains how to avoid hidden conversion costs.