IBAN Validator
🔒 Runs in your browser
✓ Valid IBAN
✗ Invalid IBAN
The mod-97 checksum runs entirely in your browser; the IBAN is never transmitted or stored.
How the mod-97 check works
Every IBAN follows the ISO 7064 MOD 97-10 standard: the first four characters (country code and check digits) move to the end of the string, each letter becomes a number (A=10, B=11, … Z=35), and the resulting number — however long — must leave remainder 1 when divided by 97. A single mistyped character anywhere in the IBAN changes that remainder, so the checksum catches almost every transcription error.
Romanian IBAN structure
A Romanian IBAN is always exactly 24 characters: "RO" + 2 check digits + a 4-letter bank code (e.g. BTRL for Banca Transilvania) + 16 alphanumeric characters identifying the account inside that bank. An unrecognized bank code doesn't make the IBAN invalid — it may belong to a newer bank not yet in our list. And a structurally valid IBAN is not proof that the account exists: banks still reject payments to non-existent accounts even when the checksum is correct.
Frequently asked questions
Is my IBAN sent to a server?
No. The checksum runs entirely in your browser; the IBAN is never transmitted or stored.
How does IBAN validation work?
The first four characters move to the end, letters become numbers (A=10 … Z=35), and the resulting number must leave remainder 1 when divided by 97 (ISO 7064 MOD 97-10).
Does a valid IBAN mean the account exists?
No — it only proves the number is structurally correct. Banks reject payments to non-existent accounts even when the IBAN checksum is fine.