IBAN Validator

IBAN Validator: Check Your Bank Details

Whether you are making a transfer or getting an IBAN from a customer on an invoice, a single typo in the bank details is enough to send money to the wrong place. This free IBAN validator checks format, length and especially the check digits using the standard MOD-97 algorithm (ISO 13616), so you catch typos and swapped digits before you set up a payment. The check runs entirely in your browser, so your bank details never leave your device.

How is a German IBAN structured?

A German IBAN is always 22 characters long and is made up as follows:

• Country code "DE" (2 characters)
• two check digits (2 characters)
• 8-digit bank sort code (Bankleitzahl)
• 10-digit account number

The same logic applies internationally: every IBAN country has a fixed country code and its own length, for example 34 characters for France or 27 for Italy. That is why the validator also checks the per-country length.

How the MOD-97 check works

The international bank account number (IBAN, ISO 13616) contains two check digits computed from all the other characters. The tool follows the official algorithm: the first four characters move to the end, letters become numbers (A=10 to Z=35) and the whole number is computed modulo 97. If the remainder is exactly 1, the check digits are correct. This ISO-7064 calculation is agreed internationally and applied identically everywhere.

Worked example: For the sample IBAN DE89 3704 0044 0532 0130 00, the "DE" is first translated into numbers (D=13, E=14). After moving the first four characters to the end and converting all letters, the full digit string is divided by 97. If the remainder is exactly 1, the validator declares the IBAN formally valid.

What the validator checks

• Format: verifies the IBAN starts with a valid country code and contains only allowed characters.
• Length: checks the precise per-country length, for example 22 characters for Germany and 34 for France.
• Check digits: verifies the MOD-97 calculation, the real typo filter that catches swapped and missing positions.

What this validator does not check

A technically valid IBAN does not mean the account behind it exists, is active or that the recipient name matches. Confirming an account would require the bank and would send sensitive data to a server. This tool deliberately works 100 % locally and only verifies the mathematical validity. For payments, always cross-check the recipient name with the booking.

What you can use the validator for

• Checking invoice details: catch typos before you transfer.
• Form fields: check input in shops or apps for plausibility.
• Privacy friendly: check directly on your device without data transfer, ideal for customer IBANs too.

Worked example with a typo

If you change just a single digit of a valid IBAN, the check digits almost always change as well. For example, a swapped position in DE89 3704 0044 0532 0130 00 means the MOD-97 calculation no longer returns a remainder of 1, and the validator flags the error immediately. This is exactly what makes the check digits a reliable filter against the most common input errors when paying and when typing invoices.

Limits in clear view

The validator only confirms the mathematical validity of an IBAN. It can neither check whether the account actually exists, whether it is enabled for incoming transfers, nor whether the stated recipient name matches the account holder. A formally valid IBAN is therefore a necessary, but not a sufficient, condition for a successful transfer.

Frequently asked questions

Read more about this tool

How exactly does the validator check an IBAN?

The tool runs the internationally agreed ISO 7064 MOD-97-10 check. It first removes any spaces from the IBAN. Then the first four characters (the country code and the check digits) move to the end of the string. Letters are converted to numbers: A becomes 10, B becomes 11 and so on up to Z for 35. The resulting digit string forms a very large number that is divided by 97. If the remainder is exactly 1, the check digits are correct and the IBAN counts as formally valid. On top of that the tool verifies the country code and the per-country length, for Germany 22 characters. This combination catches the everyday input errors: a swapped digit, a missing position or a wrong letter.

Why the check digit matters for SEPA payments

With the Single Euro Payments Area (SEPA), a single IBAN is enough to start a transfer in Germany and 35 further countries. The IBAN bundles details that used to be separate into one number: the country code, the bank sort code and the account number. It is joined by the Business Identifier Code (BIC, also called the SWIFT code), which identifies the bank itself without revealing the account inside it. Because the IBAN follows ISO 13616 worldwide, one and the same checker can examine account numbers from dozens of countries without needing a central database. The check digit is the trusted safeguard that lets you spot errors before you send, instead of correcting a misdirected payment later.

What the validator can and cannot do

The line to draw is important. The validator confirms that an IBAN is mathematically clean, so its structure and check digits are right. Whether the account behind it actually exists, whether it is enabled for incoming payments and whether the recipient name matches the holder is beyond its reach. Only the bank can answer that, for example through an account validation or a real-time enquiry that sends sensitive data to a server. When you pay an invoice, pair the formal check with a review of the recipient name and the account against earlier statements. A valid IBAN is a necessary, but not a sufficient, condition for a successful transfer.

Does the check really run fully locally?

Yes. The whole calculation takes place in your browser and neither your IBAN nor any other input is sent to a server or stored. No number ever leaves your device. For banking data that is a real privacy advantage: there is no log file, no external lookup and no record of which account numbers you have checked. Everything stays with you.