Validate IBAN

Check an international bank number with the ISO 7064 MOD-97-10 checksum.

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ToolIBAN Validator
Input
Output
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Preview

How it works

Whitespace is removed, the first four characters move to the end, letters become A=10 through Z=35, and the decimal stream is divided modulo 97. A valid result leaves remainder 1 after country, check digits, and BBAN structure are checked.

  • Country-specific lengths are required because IBAN formats differ.
  • Checksum success cannot prove that an account exists.

Worked example

A well-formed UK IBAN
The Wikipedia reference example for GB
Input
											GB82 WEST 1234 5698 7654 32
Output
												Valid: yes
Formatted: GB82 WEST 1234 5698 7654 32
Country code: GB
Check digits: 82
Bban: WEST12345698765432
Reason: Passes the mod-97 checksum.

When to use this

SEPA payment forms, payroll imports, and accounts-payable workflows validate IBANs.

Edge cases

  • Changing one check digit changes the MOD-97 remainder.
  • A correct checksum with the wrong country length is rejected.
  • A valid IBAN does not prove the account is open or owned by the named person.

References