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Ireland IBAN Validator

Validates an Irish IBAN: the mod-97 checksum, the 22-character length and the structure, with the bank code identified.

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In short An Irish IBAN is exactly 22 characters: IE, two check digits, then 4 letters, then 6 digits, then 8 digits — so the 4 characters after the check digits are the bank code — AIBK in the example — the next 6 are the six-digit sort code, 931152, and the remaining 8 are the account, 12345678. Ireland uses the same shape as the UK — four letters, a six-digit sort code, eight digits of account — because the two banking systems grew up together. The sort code is called the NSC in Ireland. The checksum is ISO 7064 MOD-97-10: move the first four characters to the end, turn each letter into its position in the alphabet plus nine, and read the result as one long number, which must leave remainder 1 when divided by 97. That catches every single-character mistake and almost every swap of two neighbouring characters, which is what it was designed for and why an IBAN is worth checking before you pay rather than after. What it cannot do is tell you the account exists, is open, or belongs to the person you think — a random string of the right shape passes about once in 97 tries, and no amount of arithmetic reaches into a bank. This page runs entirely in your browser, so the number you type is not sent anywhere.

How to use the Ireland IBAN Validator

  1. Paste the Irish IBAN — spaces and dashes are fine.
  2. Read the three checks: mod-97, length and structure.
  3. If it fails, the page says which check failed and what that usually means.

About the Ireland IBAN Validator

Checks an Irish IBAN three ways — checksum, length and structure — and says which of the three failed when one does, because they mean different things.

What people use it for

  • Checking an Irish IBAN before sending money to it.
  • Finding the bank code inside an IBAN you have been given.
  • Confirming an Irish number was typed or pasted correctly.

Details

Length22 characters, always
Structure4!a6!n8!n after the check digits
In wordsIE, 2 check digits, then 4 letters, then 6 digits, then 8 digits
Bank code4 characters — AIBK in the example
ExampleIE29 AIBK 9311 5212 3456 78
Check digitsAlways between 02 and 98. 00, 01 and 99 cannot occur
PrivacyThe arithmetic runs in your browser. Nothing you type is sent anywhere

The maths behind it

This tool uses ISO 7064 MOD-97-10 — move the first four characters to the end, replace each letter with its position plus nine, and a valid IBAN leaves remainder 1 on division by 97. On top of that, Irish IBANs are exactly 22 characters and follow 4!a6!n8!n. Every intermediate value is shown on screen, so the result can be checked by hand.

Three checks, reported separately on purpose. A length error means a character is missing or extra, a structure error means a letter sits where a digit belongs, and a checksum failure with both of those right means a genuine typo inside the number — most often two neighbouring characters swapped.

Where this tool stops

It checks arithmetic and shape. It cannot tell you the account exists or who it belongs to, it does not look the bank up, and it does not verify any national check digits Ireland may use inside its own account number — those are separate rules, computed differently, and passing mod-97 says nothing about them.

Frequently asked questions

How many characters is an Irish IBAN?
Exactly 22, with no exceptions. After the two check digits the structure is 4!a6!n8!n — 4 letters, then 6 digits, then 8 digits. A number of any other length is not an Irish IBAN, whatever else about it looks right.
Is an Irish IBAN the same format as a British one?
Structurally yes: 4!a6!n8!n and twenty-two characters in both. The difference is the country code, and that is enough to change the check digits, so the two are never interchangeable.
Where is the bank code in an Irish IBAN?
The 4 characters after the check digits are the bank code — AIBK in the example — the next 6 are the six-digit sort code, 931152, and the remaining 8 are the account, 12345678.
Does a valid checksum mean the account exists?
No, and this is the thing worth taking away. Mod-97 proves the number is internally consistent — that it was probably typed correctly. It says nothing about whether the account is open, or whose it is. A random string of the right length passes about once in every 97 attempts. Only the bank can confirm the rest.
Is it safe to paste an IBAN here?
The checking happens in your browser and the number is never sent to a server — there is no request to make one. An IBAN is not a secret the way a card number is, since it is printed on every invoice you send, but it is still yours, and it does not leave your machine here.
Is there a limit on how often I can use the Ireland IBAN Validator?
Free, unlimited, and no email address required. You can use it a hundred times a day and nothing changes.
Does anything I enter leave my computer?
No. The Ireland IBAN Validator runs entirely in your browser using JavaScript. Your input never reaches inputtesthub.com or any third party — open your browser's Network tab while you use it and you will see no request go out.
How is the result calculated?
It uses ISO 7064 MOD-97-10 — move the first four characters to the end, replace each letter with its position plus nine, and a valid IBAN leaves remainder 1 on division by 97. On top of that, Irish IBANs are exactly 22 characters and follow 4!a6!n8!n. The full working is printed under the result, so you can follow every step rather than trusting a black box.
What is the Ireland IBAN Validator used for?
The jobs it is built for: checking an Irish IBAN before sending money to it. Finding the bank code inside an IBAN you have been given. Confirming an Irish number was typed or pasted correctly. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Is there anything the Ireland IBAN Validator cannot do?
It checks arithmetic and shape. It cannot tell you the account exists or who it belongs to, it does not look the bank up, and it does not verify any national check digits Ireland may use inside its own account number — those are separate rules, computed differently, and passing mod-97 says nothing about them. Knowing where a tool stops being trustworthy matters more than the cases where it works.
What figures does the Ireland IBAN Validator work from?
Length is 22 characters, always. Structure is 4!a6!n8!n after the check digits. In words is IE, 2 check digits, then 4 letters, then 6 digits, then 8 digits. These are printed on the page itself, so you do not have to take them on trust.
Will this work on a tablet?
Yes. The page is responsive and the page works in Chrome, Safari, Firefox, Edge and Samsung Internet on both Android and iOS. There is no app to install and nothing to sign into.

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