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Bulgaria IBAN Validator

Validates a Bulgarian IBAN: the mod-97 checksum, the 22-character length and the structure, with the BIC bank code identified.

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In short A Bulgarian IBAN is exactly 22 characters: BG, two check digits, then 4 letters, then 4 digits, then 2 digits, then 8 letters or digits — so the 4 characters after the check digits are the BIC bank code — BNBG in the example — the next 4 are the four-digit branch, 9661, and the remaining 10 are the account, 1020345678. Bulgaria puts four letters of the bank’s BIC first and a four-digit branch number after it, so a Bulgarian IBAN identifies the branch as well as the bank before the account number starts. 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 Bulgaria IBAN Validator

  1. Paste the Bulgarian 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 Bulgaria IBAN Validator

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

Details

Length22 characters, always
Structure4!a4!n2!n8!c after the check digits
In wordsBG, 2 check digits, then 4 letters, then 4 digits, then 2 digits, then 8 letters or digits
BIC bank code4 characters — BNBG in the example
ExampleBG80 BNBG 9661 1020 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, Bulgarian IBANs are exactly 22 characters and follow 4!a4!n2!n8!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 Bulgaria 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 Bulgarian IBAN?
Exactly 22, with no exceptions. After the two check digits the structure is 4!a4!n2!n8!c — 4 letters, then 4 digits, then 2 digits, then 8 letters or digits. A number of any other length is not a Bulgarian IBAN, whatever else about it looks right.
What are the four letters in a Bulgarian IBAN?
The first four characters of the bank’s BIC. They are letters by definition in the registry structure, which is why this page can separate them from the branch and account with certainty.
Where is the bank code in a Bulgarian IBAN?
The 4 characters after the check digits are the BIC bank code — BNBG in the example — the next 4 are the four-digit branch, 9661, and the remaining 10 are the account, 1020345678.
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 Bulgaria 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.
Can you see what I put into this page?
No. The Bulgaria IBAN Validator runs entirely in your browser using JavaScript. Because the work happens locally, the page also keeps working if your connection drops, and closing the tab is all it takes to discard everything.
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, Bulgarian IBANs are exactly 22 characters and follow 4!a4!n2!n8!c. The full working is printed under the result, so you can follow every step rather than trusting a black box.
When would I actually need the Bulgaria IBAN Validator?
In practice it gets used for three things: checking a Bulgarian IBAN before sending money to it. Finding the BIC bank code inside an IBAN you have been given. Confirming a Bulgarian 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 Bulgaria 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 Bulgaria 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 22 characters, always. Structure is 4!a4!n2!n8!c after the check digits. In words is BG, 2 check digits, then 4 letters, then 4 digits, then 2 digits, then 8 letters or digits. These are printed on the page itself, so you do not have to take them on trust.
Does the Bulgaria 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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