← Blogby Marcell Almeida

How to validate IBAN numbers online

Paste an IBAN — verify country code, length, and mod-97 check digit.

Payment forms reject invalid IBANs before they reach the bank. The IBAN Validator checks country-specific length rules and the mod-97 checksum — paste only, no server lookup.

Try it — paste IBAN number

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How it works

  1. Paste IBAN — with or without spaces.
  2. Format check — country code and length validated.
  3. Checksum — mod-97 check digit verified.

Mod-97 algorithm

IBAN check digits use ISO 7064 mod 97-10. Rearranging country and check digits, converting letters to numbers, and dividing by 97 must leave remainder 1.

Related validators

For card numbers, use the Luhn Checker.

The How to validate IBAN numbers online is free, runs locally, and never sends your data to a server. More developer tools at maratool.com.