IBAN Validator

Use this free IBAN Validator to instantly check whether an International Bank Account Number is correctly formatted for any of the 80+ countries that use the IBAN standard. The tool performs a full MOD-97 checksum verification and validates country-specific length and format rules. This validator uses the ISO 13616 IBAN standard, maintained by SWIFT.

Whether you are processing payments, building a fintech app, or cleaning up a database of account numbers, you can validate individual IBANs or paste in a batch list. Developers can also access validation via the REST API endpoint for integration into payment flows, KYC pipelines, or banking applications.

• Supports all 80+ IBAN countries worldwide
• Country-specific length and format validation
• MOD-97 checksum verification (ISO 13616)
• Real-time validation with detailed error reporting
• Bulk validation for multiple IBANs at once
• IBAN component breakdown (country, bank, branch, account)

An IBAN consists of up to 34 alphanumeric characters with a specific structure that varies by country. Understanding this structure is crucial for proper validation and implementation.

IBAN Components:

Country Examples:

The IBAN validation process follows a standardized algorithm that ensures both structural and mathematical correctness of the account number.

Validation Steps:

1. Length Check: Verify the IBAN length matches the country's standard
2. Character Check: Ensure only valid alphanumeric characters are used
3. Country Code: Validate the first two letters against ISO 3166-1
4. Rearrangement: Move the first 4 characters to the end
5. Character Substitution: Replace letters with numbers (A=10, B=11, etc.)
6. MOD-97 Calculation: Calculate remainder when divided by 97
7. Result Verification: Valid IBAN should have remainder of 1

Implementation Example:

// IBAN Validation Algorithm
function validateIBAN(iban) {
  // Remove spaces and convert to uppercase
  const cleanIban = iban.replace(/\s/g, '').toUpperCase();

  // Check basic format
  if (!/^[A-Z]{2}[0-9]{2}[A-Z0-9]+$/.test(cleanIban)) {
    return false;
  }

  // Rearrange: move first 4 chars to end
  const rearranged = cleanIban.slice(4) + cleanIban.slice(0, 4);

  // Convert letters to numbers (A=10, B=11, etc.)
  const numericString = rearranged.replace(/[A-Z]/g, char =>
    (char.charCodeAt(0) - 55).toString()
  );

  // Calculate MOD-97
  return mod97(numericString) === 1;
}

// MOD-97 for large numbers (string-based)
function mod97(numStr) {
  let remainder = 0;
  for (let i = 0; i < numStr.length; i++) {
    remainder = (remainder * 10 + parseInt(numStr[i])) % 97;
  }
  return remainder;
}

// Usage examples
console.log(validateIBAN('GB82 WEST 1234 5698 7654 32')); // true
console.log(validateIBAN('DE89 3704 0044 0532 0130 00')); // true
console.log(validateIBAN('FR14 2004 1010 0505 0001 3M02 606')); // true