IBAN Checker

What an IBAN is

An IBAN (International Bank Account Number) is the number that identifies one bank account so that money can be sent to it from anywhere in Europe, and from many countries outside it. Since the old Irish payment systems were replaced by SEPA in 2014, it’s also what you use for an ordinary transfer between two Irish accounts.

Every IBAN has the same three parts:

• a country code, two letters: IE for Ireland
• two check digits, worked out from everything else in the IBAN
• the account details in that country’s own format, which in Ireland means the bank code, the sort code and the account number

IBANs are printed in groups of four to make them easier to read out and type, but the spaces aren’t part of the number. This checker ignores them, along with dashes and lower case, so you can paste one straight from an email or an invoice.

How an Irish IBAN is made up

An Irish IBAN is always 22 characters. Here is the example from the official IBAN register, which belongs to no real account:

IE29 AIBK 9311 5212 3456 78

So if you know someone’s sort code and account number, they are sitting inside their IBAN, and the checker shows them both.

Irish bank codes

These are the bank codes the checker recognises. Each one has been checked against the bank’s own published details or an official source, as of 3 October 2026. Many credit unions and smaller providers have codes of their own, so an IBAN with a code that isn’t listed can still be perfectly valid: the checker will say so and tell you it doesn’t know the bank.

Ulster Bank, KBC and Danske Bank (once National Irish Bank) have all left. Their IBANs still pass the check, because the check only looks at the numbers, but the accounts behind them have closed or moved. Ulster Bank closed its current and deposit accounts in 2022 and 2023. KBC’s deposit accounts moved to Bank of Ireland in February 2023 and got new IBANs. So if someone gives you an IBAN with one of those codes, ask them for their new one before you send anything.

How the IBAN check works

The check digits are what make it possible to check an IBAN without asking the bank. The method is set out in the international standard for IBANs, ISO 13616, and uses a calculation called MOD 97-10 from another standard, ISO 7064. You can do it by hand in four steps.

1. Take out the spaces and move the first four characters to the end:

   AIBK93115212345678IE29

2. Turn every letter into a number: A is 10, B is 11 and so on, up to Z at 35:

   1018112093115212345678181429

3. Divide that very long number by 97 and keep the remainder.
4. If the remainder is 1, the IBAN is valid. For the example it is 1.

The number is far too long for a calculator or a spreadsheet, which round it off, so software does the division a few digits at a time. That’s what this checker does, in your browser.

The checker also makes sure the IBAN has the right length for its country. Irish IBANs are 22 characters, German ones 22, French ones 27 and Norwegian ones only 15. It knows the length for all 89 countries in the SWIFT IBAN Registry.

What the check can and can’t tell you

The check catches almost every typo: a wrong character, or two characters swapped round. A random mistake has about a 1 in 97 chance of getting through, and the length check catches most of the rest. When an IBAN fails, the checker says why: the wrong length, check digits that don’t match, a letter where a number should be, or a country that doesn’t use IBANs.

What it can’t tell you is whether the account exists, whether it’s still open, or whose name is on it. A valid IBAN only means the number is well formed. Your bank can tell you more: since 9 October 2025, banks in the euro area have to check the name you enter against the name on the account before you send a transfer, and warn you if they don’t match.

IBAN and BIC: what’s the difference?

The IBAN identifies an account. The BIC (Bank Identifier Code, also called a SWIFT code) identifies a bank. A BIC is 8 or 11 characters: the same four letters as the bank code, the country code, two characters for the location, and sometimes three more for a branch. AIB’s BIC, for example, is AIBKIE2D.

For a payment in euro within the SEPA area, which covers the EU and several other European countries, the UK and Switzerland among them, the IBAN is all you need: a bank can’t insist on the BIC as well. You may still be asked for one when money is coming from outside SEPA, from the US say.

The checker shows the BIC that usually goes with an Irish bank code. Some banks have more than one, so if the bank gives you a different one, use the bank’s.

Is it safe to give out your IBAN?

Mostly, yes. Your IBAN is meant to be shared: it’s how people pay you, and it goes on every invoice and payslip form. On its own, it can’t be used to take money out of your account by card or online banking.

The one thing to watch is direct debits. A business needs your IBAN to set one up, and it’s possible for someone to set up a direct debit using an IBAN that isn’t theirs. The rules are on your side: you can get your money back for any direct debit within 8 weeks with no questions asked, and up to 13 months if you never agreed to it. So keep an eye on your statements, and tell your bank straight away about any direct debit you don’t recognise.

It’s also worth knowing that any company in the EU that takes payments by direct debit or bank transfer has to accept an IBAN from any EU country. If a business won’t take your IBAN because it doesn’t start with IE, that isn’t allowed.

Your IBAN stays on your device

The best-known IBAN sites send what you type to their own servers to be checked. This one doesn’t: the check runs entirely in your browser, and once the page has loaded it makes no requests at all. Nothing is stored, logged or sent anywhere, so you can check your own IBAN, or a customer’s, without handing it to a website. If you want to see for yourself, open your browser’s developer tools, go to the Network tab and check an IBAN: nothing appears.