IBAN Validator
ValidatorValidate IBAN (International Bank Account Number) codes. Checks the country-specific length and recomputes the ISO 7064 MOD 97-10 check digits. Runs entirely in your browser.
About this tool
About IBAN Validator
An IBAN (International Bank Account Number) is an internationally standardized code, defined by ISO 13616, used to identify individual bank accounts across borders for cross-border payments, SEPA transfers, and international wire instructions. It's made up of a 2-letter country code, 2 check digits, and a country-specific BBAN (Basic Bank Account Number). This validator confirms the country is recognized, the length matches that country's official IBAN length, and the check digits satisfy the ISO 7064 MOD 97-10 algorithm.
The validator strips whitespace, looks up the country from the first 2 letters against a table of 68+ known IBAN countries and their exact lengths, rearranges the IBAN to move the country code and check digits to the end, expands every letter to its two-digit value (A=10..Z=35), and confirms the resulting big integer is congruent to 1 modulo 97 — the defining property of a valid IBAN check digit.
Use this to verify an IBAN collected from a customer before initiating a SEPA or international wire transfer, to debug why an IBAN is being rejected by a payment gateway, or to sanity-check an IBAN pasted from an invoice, contract, or banking portal.
Instant, fully client-side validation with no data ever leaving your browser — your bank account number is never transmitted anywhere. Note this checks structural validity only — it does not confirm the account is open, active, or belongs to a specific person, which requires a bank-side lookup.
Key Features
- Recognizes 68+ IBAN countries with exact length validation
- Decodes the country, BBAN, and check digits
- Recomputes and compares the ISO 7064 MOD 97-10 check digits
- BigInt-based computation for exact precision on large numbers
- Verified against 4 real published IBAN worked examples
- 100% browser-based, no data ever transmitted
FAQ
IBAN Validator — Frequently Asked Questions
What is an IBAN and why does it have check digits?
An IBAN (International Bank Account Number) is a standardized code used to identify a specific bank account internationally. The 2 check digits, positions 3-4 of the IBAN, let banking systems catch typos and transposed digits before a payment is sent, using the ISO 7064 MOD 97-10 algorithm.
How is the IBAN check digit calculated?
Move the first 4 characters (country code + check digits) to the end of the string, expand every letter to its two-digit value (A=10 through Z=35), and confirm the resulting large number is congruent to 1 when divided by 97. To generate a check digit instead of validate one, the same process is run with '00' as a placeholder, and the check digits are set to 98 minus the remainder.
Why does my IBAN fail validation?
The most common cause is a single mistyped or transposed character, or an incorrect length for the stated country — each country has one fixed IBAN length. Also confirm there are no spaces (many printed IBANs are grouped in blocks of 4 for readability, which need to be stripped before validating).
Does a valid IBAN mean the bank account exists?
No. This validator only confirms the code is structurally correct — the right length for its country and a check digit that satisfies the mod-97 algorithm. It cannot confirm the account is open, active, or held by a specific person; that requires a live lookup against the issuing bank.
Which countries use IBANs?
IBANs are mandatory throughout the European Union and the wider SEPA zone, and are also used by many countries in the Middle East, and parts of the Caribbean and former Soviet states. Notably, the US, Canada, Australia, and most of Asia do not use IBANs for domestic banking.
Tips
- Strip spaces before validating — printed IBANs are often grouped in 4-character blocks for readability
- Each country has exactly one valid IBAN length — a mismatch there means the code was truncated or has extra characters
- If the check digit fails, try re-copying the IBAN from its original source — the most common error is a single transposed character
- This validator never sends your IBAN anywhere — the check digits are recomputed entirely in your browser
Explore more
Related Tools
Other tools that might be useful for your workflow