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Gibraltar IBAN Validator

Validates a Gibraltar IBAN: the mod-97 checksum, the 23-character length and the structure, with the BIC-derived bank code identified.

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In short A Gibraltar IBAN is exactly 23 characters: GI, two check digits, then 4 letters, then 15 letters or digits — so the 4 characters after the check digits are the BIC-derived bank code — NWBK in the example — and the remaining 15 are the account number, 000000007099453. Gibraltar’s BBAN is four letters of bank code and fifteen characters that may be letters or digits, so the account part is not necessarily numeric. 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 Gibraltar IBAN Validator

  1. Paste the Gibraltar 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 Gibraltar IBAN Validator

Checks a Gibraltar 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 a Gibraltar IBAN before sending money to it.
  • Finding the BIC-derived bank code inside an IBAN you have been given.
  • Confirming a Gibraltar number was typed or pasted correctly.

Details

Length23 characters, always
Structure4!a15!c after the check digits
In wordsGI, 2 check digits, then 4 letters, then 15 letters or digits
BIC-derived bank code4 characters — NWBK in the example
ExampleGI75 NWBK 0000 0000 7099 453
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, Gibraltar IBANs are exactly 23 characters and follow 4!a15!c. 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 Gibraltar 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 a Gibraltar IBAN?
Exactly 23, with no exceptions. After the two check digits the structure is 4!a15!c — 4 letters, then 15 letters or digits. A number of any other length is not a Gibraltar IBAN, whatever else about it looks right.
Is a Gibraltar IBAN a UK one?
No. Gibraltar has its own country code, GI, and its own twenty-three character format — one longer than the UK’s twenty-two, and a different structure. Putting GB in front of a Gibraltar account fails the checksum.
Where is the bank code in a Gibraltar IBAN?
The 4 characters after the check digits are the BIC-derived bank code — NWBK in the example — and the remaining 15 are the account number, 000000007099453.
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.
Do I need an account to use the Gibraltar IBAN Validator?
There is no cost and no cap. The Gibraltar IBAN Validator is not a demo of a paid product, so nothing is held back or watermarked.
Is what I paste into the Gibraltar IBAN Validator stored?
No. The Gibraltar 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.
What formula does the Gibraltar IBAN Validator use?
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, Gibraltar IBANs are exactly 23 characters and follow 4!a15!c. The full working is printed under the result, so you can follow every step rather than trusting a black box.
What do people use the Gibraltar IBAN Validator for most?
Typical uses: checking a Gibraltar IBAN before sending money to it. Finding the BIC-derived bank code inside an IBAN you have been given. Confirming a Gibraltar 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 Gibraltar 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 Gibraltar 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 Gibraltar IBAN Validator work from?
Length is 23 characters, always. Structure is 4!a15!c after the check digits. In words is GI, 2 check digits, then 4 letters, then 15 letters or 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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