IBAN Validator

What Is an IBAN?

An International Bank Account Number (IBAN) is a standardized format for identifying bank accounts across national borders, defined by ISO 13616. It starts with a two-letter country code, followed by two check digits, and then a country-specific Basic Bank Account Number (BBAN) that encodes the bank, branch, and account. IBANs are mandatory for cross-border EUR transfers within the Single Euro Payments Area (SEPA) and are widely used in international wire transfers worldwide. The format varies by country — a German IBAN is 22 characters, a UK IBAN is 22, a French IBAN is 27 — but the check-digit algorithm is universal.

How IBAN Validation Works

IBAN validation uses a mod-97 checksum defined in ISO 7064. The algorithm rearranges the IBAN by moving the first four characters (country code + check digits) to the end, converts every letter to its numeric equivalent (A=10, B=11, … Z=35), and computes the remainder when dividing the resulting number by 97. A valid IBAN always produces a remainder of 1. This catches all single-character errors and most transpositions — making it a reliable first-pass filter before submitting a payment instruction. This tool also validates that the BBAN portion matches the expected format for the declared country.

IBAN in Cross-Border Payments

Validating IBANs at the point of entry — in payment forms, bulk import files, and ERP interfaces — prevents failed transfers, return fees, and delayed settlements. I build payment integrations and data pipelines that validate, format, and route international bank details across systems. See integration services, explore ETL and data pipeline services, or get in touch.