An IBAN can be up to 34 characters long, mixing letters and digits, and a single mistyped character can send a payment to the wrong account or have it rejected days later. This validator runs the official mod-97 check defined for IBANs: it rearranges the number, converts letters to digits, and verifies that the whole value leaves a remainder of one when divided by 97. It also identifies the country from the first two letters and checks the overall shape, so you get a verdict you can act on before money moves. The check is the same one banks use, it runs entirely in your browser, and it catches the transcription errors that cause the most expensive payment mistakes.
Quick Answer: Paste an IBAN to run the official mod-97 check and confirm its country.
Free Online Tool
IBAN Validator
The same mod-97 check banks run, before money moves.
How to Use the IBAN Validator
- Type or paste an IBAN, spaces allowed.
- Press Validate to run the mod-97 check.
- Read the verdict and the detected country.
- If it fails, compare the IBAN character by character with the source.
- Correct the error and validate again before using the number.
Key Features
- Official ISO mod-97 IBAN validation.
- Country identification from the IBAN prefix.
- Accepts IBANs with or without spaces.
- Length and character checks before the checksum.
- Private, instant, and free with no data sent anywhere.
Best Practices and Tips
- Always copy an IBAN rather than retyping it; manual transcription is where most IBAN errors are born.
- The first two letters are the country code and the next two digits are the check digits, not part of the account number.
- A valid mod-97 result proves the IBAN is well-formed, not that the account exists or belongs to the intended person.
- Different countries have different IBAN lengths, so a length check alone is never enough; the mod-97 check is the real test.
- When a payment is rejected for an invalid IBAN, validate here first before contacting the recipient.
Common Mistakes to Avoid
- Dropping the country code and check digits and validating only the domestic account number.
- Confusing the letter O with the digit 0, or the letter I with the digit 1, in a printed IBAN.
- Assuming a valid IBAN guarantees the account is open; closed accounts can still have well-formed numbers.
- Adding spaces in the wrong places and then treating the spaced string as a different number; spaces are ignored by the check.
Frequently Asked Questions
How does the mod-97 check work?
The first four characters of the IBAN are moved to the end, every letter is replaced by two digits where A is 10 and Z is 35, and the resulting long number is divided by 97. A valid IBAN leaves a remainder of exactly one, a property the check digits were chosen to guarantee.
Why do IBANs start with a country code?
Because the IBAN is an international format, the first two letters identify the country so any bank worldwide can route and validate the number. The length and internal structure after that vary by country, reflecting each country’s domestic account format.
Does a valid IBAN mean the payment will succeed?
Not necessarily. Validity means the number is well-formed and passes its checksum, but the account could be closed, the name could mismatch, or the bank could reject the transfer for other reasons. Validity is a necessary check, not a guarantee of delivery.
What if my IBAN fails validation?
Compare it character by character with the original source, watching for the classic confusions: O versus 0, I versus 1, and transposed neighbours. If the source itself fails, ask the account holder to confirm the number, because a misprinted IBAN does happen.
Are spaces part of the IBAN?
No, spaces are only a display convention that groups the characters in fours for readability. The validator ignores spaces, and payment systems strip them too, so an IBAN with or without spaces is the same number.