IBAN Validator
NewValidate an International Bank Account Number against the ISO 13616 checksum and see its country, check digits, and BBAN breakdown.
———————Frequently Asked Questions
What checksum algorithm does IBAN validation use?
ISO 13616 defines a mod-97 checksum: the first four characters (country code + check digits) are moved to the end, letters are converted to numbers (A=10 through Z=35), and the resulting numeric string must be congruent to 1 modulo 97.
Why does the tool compute mod-97 digit-by-digit instead of all at once?
After expanding letters to two-digit codes, a long IBAN can become a 30+ digit number, which loses precision in standard JavaScript floating-point math. Taking the modulus one digit at a time keeps every intermediate value small and exact.
What does the tool check besides the checksum?
It also verifies the IBAN's total length against the expected length for that specific country — each country has a fixed IBAN length, so a checksum-valid but wrong-length string is flagged as invalid too.
Does this confirm the account actually exists at a bank?
No — like a credit card checksum, this only confirms the IBAN is structurally and mathematically well-formed. Confirming a real account requires the bank's own verification systems.
Which countries are covered?
The expected-length lookup table covers roughly 70 IBAN-participating countries as published by SWIFT/the IBAN registry; if a country code isn't recognized, the tool still runs the mod-97 checksum but can't validate the exact length.