IBAN Validator - Check IBAN number with modulo 97
Enter an IBAN number and instantly check whether it is valid. Supports all countries. Fully client-side — no data is stored.
Note:All generated data is entirely fictional and not suitable for use as real personal information.
The modulo 97 algorithm
- Move the first 4 characters (country code + check digits) to the end.
- Replace each letter with a number: A=10, B=11, ..., Z=35.
- Divide the resulting number by 97.
- If the remainder equals 1, the IBAN is valid.
This algorithm is standardized in ISO 13616 and is used worldwide for all IBAN numbers, regardless of the country of origin.
Frequently Asked Questions
How does IBAN validation work?
The validator uses the modulo 97 algorithm (ISO 7064). The first 4 characters of the IBAN are moved to the end, all letters are converted to numbers (A=10, B=11, etc.) and the resulting number must yield remainder 1 when divided by 97.
Which countries are supported?
The validator supports IBAN numbers from all countries that use the IBAN system, including the Netherlands, Germany, Belgium, France, Spain, the United Kingdom and more than 70 other countries.
Can I use this to check if an IBAN actually exists?
No. The validator only checks whether the IBAN is mathematically valid (modulo 97 check). Whether the IBAN is actually registered with a bank can only be verified with the relevant bank.
Are entered IBAN numbers stored?
No. The validation runs entirely in your browser (client-side). No data is sent or stored.
Why do developers use an IBAN validator?
Developers use IBAN validators to test input validation, to check whether generated test data is correct, and for building payment forms that accept IBAN numbers.