Question 1

What does mod-97 mean?

Accepted Answer

The IBAN check uses ISO 7064 mod 97-10: rearrange the IBAN (move first 4 chars to the end), replace letters with two-digit numbers (A=10, B=11, ..., Z=35), interpret as a huge integer, divide by 97. A valid IBAN gives remainder 1. The check digits (positions 3-4 of the IBAN) are computed at issuance to make this work out. A single-character typo almost always produces a wrong remainder.

Question 2

Why does length matter, isn't checksum enough?

Accepted Answer

Checksum catches most typos but length validation catches different errors: missing/extra characters that happen to checksum correctly. Each country has a fixed IBAN length (Germany: 22, UK: 22, France: 27, Cyprus: 28, Norway: 15, etc.). The country code is the first 2 letters; the validator looks up that country's expected length and rejects anything different. Both checks together catch ~99% of typos.

Question 3

Can a checksum-valid IBAN still be wrong?

Accepted Answer

Yes. The checksum verifies *format* (no typo), not *existence*, there might be no account at that bank with that number. The only true verification is sending a small amount and waiting for it to arrive (or be rejected). Some payment processors offer name-matching ("Confirmation of Payee" in the UK) which compares the IBAN's name to the one you typed, this catches a different class of errors (right IBAN, wrong person).

Question 4

Why does Italy's IBAN look so long?

Accepted Answer

27 characters: country code (2) + check digits (2) + national check character (1) + ABI code (5) + CAB code (5) + account number (12). Italy's national-level structure was preserved when joining IBAN, they had their own check char before. Other countries have their own quirks: Saudi Arabia's IBAN is 24 chars; UAE's is 23. The country-specific format is encoded in the validator's tables.

Question 5

Do all countries use IBAN?

Accepted Answer

No. SEPA countries (EU + a few neighbors) use IBAN as their primary domestic format too. Many non-SEPA countries adopted IBAN voluntarily (Saudi Arabia, UAE, Turkey, etc.) for international transfers. The US, Canada, Australia, Japan, China don't use IBAN domestically, for transfers to those countries you typically use SWIFT/BIC plus account number, not IBAN.

Question 6

What's the difference between IBAN and SWIFT/BIC?

Accepted Answer

IBAN identifies the account uniquely worldwide. SWIFT/BIC (Bank Identifier Code) identifies the bank, same as routing number conceptually. For an international wire you typically need both: BIC to route to the bank, IBAN to specify the account. SEPA payments within Europe use just IBAN (the bank can be derived). Outside SEPA, both are often required.

Question 7

What does an IBAN reveal about the account?

Accepted Answer

Country, the issuing bank (encoded in the bank code section of the BBAN), the branch in some countries, and the account number. Not: account holder name, balance, transaction history. Sharing an IBAN to receive payment is roughly as sensitive as sharing a postal address, the recipient knows where to send things but can't make withdrawals (which require additional authentication). Standard practice.

Question 8

Is the IBAN sent anywhere?

Accepted Answer

No. The mod-97 check is pure arithmetic in JavaScript. Length and country lookup use a local table. Nothing leaves the page. Useful when validating IBANs that are real (someone's actual account), since you don't want them in remote logs.

Question 9

What standards does IBAN Validator validate against?

Accepted Answer

IBAN Validator checks compliance with ISO 13616 (IBAN), IBAN Registry.

Question 10

What are the limitations of IBAN Validator?

Accepted Answer

Validates format and check digits only, does not verify account existence Does not support all country-specific formats Does not check BBAN structure rules

Country	Code	Standard Length	Verification Status
Norway	`NO`	15 Characters	Supported
Netherlands	`NL`	18 Characters	Supported
Germany	`DE`	22 Characters	Supported
France	`FR`	27 Characters	Supported
Cyprus	`CY`	28 Characters	Supported

IBAN Validator

What is IBAN Validator?

Frequently Asked Questions

Technical Deep Dive

IBAN Validator

Real-Time Feedback

Edge-Case Coverage

Actionable Output

01 Length Standards by Territory

02 Validation Logic Workflow

Runs 100% in your browser

You Might Also Need

API Response Diff

Email Address Validator

GraphQL Playground

gRPC Web Tester