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Austria IBAN Validator

Validates an Austrian IBAN: the mod-97 checksum, the 20-character length and the structure, with the Bankleitzahl, or BLZ identified.

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In short An Austrian IBAN is exactly 20 characters: AT, two check digits, then 5 digits, then 11 digits — so the 5 characters after the check digits are the Bankleitzahl, or BLZ — 19043 in the example — and the remaining 11 are the account number, 00234573201. Austria uses a five-digit Bankleitzahl where Germany uses eight, which is the single most common confusion between the two — they share a word and not a format. The account number that follows is eleven digits. 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 Austria IBAN Validator

  1. Paste the Austrian 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 Austria IBAN Validator

Checks an Austrian 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 Austrian IBAN before sending money to it.
  • Finding the Bankleitzahl, or BLZ inside an IBAN you have been given.
  • Confirming an Austrian number was typed or pasted correctly.

Details

Length20 characters, always
Structure5!n11!n after the check digits
In wordsAT, 2 check digits, then 5 digits, then 11 digits
Bankleitzahl, or BLZ5 characters — 19043 in the example
ExampleAT61 1904 3002 3457 3201
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, Austrian IBANs are exactly 20 characters and follow 5!n11!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 Austria 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 Austrian IBAN?
Exactly 20, with no exceptions. After the two check digits the structure is 5!n11!n — 5 digits, then 11 digits. A number of any other length is not an Austrian IBAN, whatever else about it looks right.
Is an Austrian BLZ the same as a German one?
No, and assuming so is the usual mistake. Both are called a Bankleitzahl, but Austria’s is five digits and Germany’s is eight, and the IBANs are 20 and 22 characters respectively. A five-digit code will never identify a German bank.
Where is the bank code in an Austrian IBAN?
The 5 characters after the check digits are the Bankleitzahl, or BLZ — 19043 in the example — and the remaining 11 are the account number, 00234573201.
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.
Are there any usage caps on the Austria IBAN Validator?
No charge and no sign-up. There is no free tier to run out of because there is no paid tier — inputtesthub.com is funded by advertising rather than by metering the page.
Is my data uploaded anywhere?
No. The Austria 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.
Can I check the maths myself?
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, Austrian IBANs are exactly 20 characters and follow 5!n11!n. The full working is printed under the result, so you can follow every step rather than trusting a black box.
What is the Austria IBAN Validator used for?
In practice it gets used for three things: checking an Austrian IBAN before sending money to it. Finding the Bankleitzahl, or BLZ inside an IBAN you have been given. Confirming an Austrian number was typed or pasted correctly. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
When is the Austria IBAN Validator not the right tool?
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 Austria 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.
Which values should I know?
Length is 20 characters, always. Structure is 5!n11!n after the check digits. In words is AT, 2 check digits, then 5 digits, then 11 digits. These are printed on the page itself, so you do not have to take them on trust.
Does the Austria IBAN Validator work on a phone?
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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