Build an IBAN from a country and account number: the two check digits are calculated
Runs in your browser. Nothing you type is sent anywhere. Checked against sources on 16 Oct 2026.An IBAN is the country code, two check digits and the national account number, called the BBAN. Choose the country, type the BBAN exactly as the bank writes it, and the check digits are calculated with the mod-97 rule, giving the full IBAN in electronic and print format. The BBAN is checked against the country's format first, so a missing digit is caught before an IBAN is made.
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The International Bank Account Number (ISO 13616) puts a country code and two check digits in front of the national account number, so a payment system can catch a mistyped account before any money moves. This checker applies the same tests a bank's system does.
| Check | What it looks at | Example of a failure |
|---|---|---|
| Country | The first two letters are in the registry | XX82... |
| Length | Exactly the country's length | A German IBAN with 20 characters, not 22 |
| Format | Letters and digits where the country puts them | A digit where a UK bank code needs a letter |
| Check digits | Remainder 1 under mod 97 | One digit typed wrong |
Calculate check digits. The second tab builds an IBAN from a country and a national account number (BBAN), after checking the BBAN's length and format.
The rest of the article, and all 6 questions about IBAN Validator and Checker, are on the IBAN Validator and Checker page.
Paste the IBAN and four checks run at once: the country code is in the IBAN registry, the length is right for that country, the account part has the right letters and digits, and the two check digits pass the mod-97 test. All four must pass for the IBAN to be valid.
Move the country code and check digits to the end, replace each letter with a number (A is 10, B is 11, up to Z at 35), and divide the whole number by 97. A valid IBAN leaves a remainder of 1. New check digits are 98 minus the remainder, with 00 in their place.
No. Validation proves the IBAN is well formed and almost certainly free of typing errors, since the mod-97 check catches every single wrong digit and every swap of two neighbouring digits. Only the bank holding the account can confirm that it is open and in the name you expect.
Yes. Paste a column from a spreadsheet, one IBAN per line, and every line is checked separately, with up to 1,000 lines at a time. The summary counts valid and invalid ones, and Copy valid IBANs gives the clean list in electronic format, without spaces.
Rates and rules change; check the source before you rely on a figure.
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