In plain words
Think of an international postal address. Every country writes addresses differently, so the post office agrees on one rule: put the country first, then the local address in that country’s own format. An IBAN does the same for bank accounts.
An International Bank Account Number (IBAN) starts with a two-letter country code, such as GB for the UK, AE for the United Arab Emirates or SA for Saudi Arabia. Next come two check digits, which let any bank spot a typo before money moves. The rest is the account number in the format that country already uses, called the Basic Bank Account Number (BBAN). The whole thing can be up to 34 characters long, and each country has its own fixed length. 1
IBANs are defined in an international standard, ISO 13616. SWIFT keeps the official registry of which countries use them and what each country’s format looks like.
How it works
How an IBAN is built and checked
Using the UK example from the SWIFT registry: GB29 NWBK 6016 1331 9268 19.
-
1
Country code: GB
Two letters from the ISO country list. They also tell a bank how long the rest should be.
-
2
Check digits: 29
Calculated from the rest of the IBAN. If one character is mistyped or two are swapped, the check almost always fails.
-
3
Bank and branch: NWBK 601613
In the UK, four letters for the bank, then the six-digit sort code.
-
4
Account number: 31926819
The same eight-digit account number used for UK payments.
How the check digits work
The check is simple arithmetic. Move the first four characters to the end, turn each letter into a number (A is 10, B is 11 and so on up to Z, which is 35), and divide the resulting long number by 97. For a valid IBAN, the remainder is always 1. Software does this in a fraction of a second, which is why a good app can tell a customer “this IBAN looks wrong” before they press send.
A valid check does not mean the account exists or belongs to the person named. It only means the number is well formed. Name checks such as Confirmation of Payee in the UK and Verification of Payee in the EU cover that part.
IBAN formats by country
Each country fixes its own length and layout. Some examples from the SWIFT IBAN registry: 1
| Country | Length | What follows the country code and check digits |
|---|---|---|
| United Kingdom (GB) | 22 | 4-letter bank code, 6-digit sort code, 8-digit account number |
| Germany (DE) | 22 | 8-digit bank code, 10-digit account number |
| France (FR) | 27 | Bank code, branch code, account number and a national check key |
| Netherlands (NL) | 18 | 4-letter bank code, 10-digit account number |
| United Arab Emirates (AE) | 23 | 3-digit bank code, 16-digit account number |
| Saudi Arabia (SA) | 24 | 2-digit bank code, 18-character account number |
On paper and in apps, IBANs are usually shown in groups of four characters to make them easier to read. In payment files they are sent without spaces.
IBAN vs sort code, account number and BIC
These numbers are often asked for together, which makes them easy to confuse. They answer different questions.
| Identifier | What it identifies | Where it is used |
|---|---|---|
| IBAN | One account, anywhere that uses IBANs | SEPA transfers, international payments, and domestic payments in many countries |
| Sort code and account number | One UK account | UK payments such as Faster Payments and Bacs. Both are already inside a UK IBAN |
| BIC (SWIFT code) | A bank, not an account. 8 or 11 characters | International transfers, especially through SWIFT. Not needed for SEPA euro transfers |
Where IBANs come from in a fintech product
Only a firm with access to a country’s banking system can create IBANs in that country. A new neobank or wallet usually gets them in one of three ways, and the choice shapes what customers see.
| Source | How it works | What to check |
|---|---|---|
| Your own licence and access | You hold accounts in your own name at the payment system or a settlement bank, and issue IBANs from your own range | Needs a licence and direct or sponsored scheme access, which takes time |
| A partner’s dedicated IBANs | A bank, EMI or BaaS partner opens a real account per customer | The IBAN belongs to the partner, so it usually changes if you change partner |
| Virtual IBANs | Each customer gets a unique number that routes into one shared master account | Country code, how other banks treat it, and how you reconcile each payment |
IBANs in the UK, EU and Gulf
- United Kingdom. Most UK bank accounts have an IBAN, but people rarely use it at home. Domestic payments run on sort code and account number. The IBAN matters for money coming in from abroad.
- European Union. IBANs are the everyday account number. Under the SEPA Regulation, euro transfers and direct debits across SEPA are made with the IBAN alone, without a BIC. 2
- Gulf. The UAE, Saudi Arabia and several other Gulf countries use IBANs for domestic transfers as well as international ones, so customers expect to see their IBAN in the app from the first day.
Example: getting paid from Germany
Leila is a UK designer. A client in Berlin wants to pay her invoice in euros.
- Her details. Leila’s account offers a euro balance with its own IBAN. She puts it on her invoice.
- The client pays. The client types the IBAN into their banking app. The app runs the check-digit test and, for a euro transfer, checks the name against the account.
- Arrival. The money arrives in Leila’s euro balance, ready to keep or convert to pounds.
- A typo avoided. When the client first typed one digit wrong, the check failed at once and the app asked them to fix it before sending.
Common misconceptions
“An IBAN shows which country my money is in.”
It shows the country of the bank that issued the number. With a virtual IBAN, the money may be held elsewhere, in a master account.
“A valid IBAN means the payment will reach the right person.”
The check digits only catch typos. They do not confirm who owns the account. Name checks do that.
“Every country uses IBANs.”
Many do, but not all. The United States, for example, uses routing and account numbers instead.
FAQ
What is an IBAN number?
An International Bank Account Number: a standard format for account numbers that starts with a two-letter country code and two check digits, followed by the bank and account details used in that country. It can be up to 34 characters long.
How many digits is a UK IBAN?
A UK IBAN has 22 characters: GB, two check digits, a four-letter bank code, the six-digit sort code and the eight-digit account number.
What is the difference between an IBAN and a BIC?
The IBAN identifies one account. The BIC, also called a SWIFT code, identifies the bank. For euro transfers within SEPA the IBAN alone is enough, while many international transfers outside SEPA still ask for both.
Do I need an IBAN for a UK payment?
Not for a payment between two UK accounts in pounds. UK transfers use the sort code and account number. You need an IBAN to receive money from abroad, for example a euro transfer from Europe.
Is it safe to give someone my IBAN?
Generally yes. An IBAN lets someone send money to you, and it is printed on invoices for that reason. Treat it like your account number, though, because it can be misused in some direct debit or impersonation scams.
Does the USA use IBANs?
No. The United States uses routing numbers and account numbers instead. To receive money from the US, you give the sender your account details and, usually, your bank's BIC.
Related terms
Sources
-
1
S
SWIFT IBAN: International Bank Account Number and the IBAN Registry
https://www.swift.com/standards/data-standards/iban-international-bank-account-number -
2
EL
EUR-Lex Regulation (EU) No 260/2012 establishing requirements for credit transfers and direct debits in euro (SEPA)
https://eur-lex.europa.eu/eli/reg/2012/260/oj
