IBAN Validator
Finance & Indian IDsCheck if an IBAN is correctly formatted and passes the mod-97 checksum. Supports 70+ countries — instant result, runs in your browser, no signup needed.
What is a IBAN?
An IBAN Validator checks whether an International Bank Account Number is correctly formatted and passes the ISO 13616 mod-97 mathematical checksum. IBANs are the standard for identifying bank accounts in international transfers across Europe, the Middle East, and dozens of other countries. A single transposed digit in an IBAN can redirect a wire transfer to the wrong account — or cause it to be rejected entirely — making format validation before sending an important step.
An IBAN begins with a two-letter ISO 3166-1 country code, followed by two check digits that satisfy the mod-97 equation, followed by the BBAN (Basic Bank Account Number) — the country-specific account identifier. The total length varies by country: UK and German IBANs are 22 characters, French and Italian IBANs are 27 characters.
This tool validates three things: the country code is a recognised IBAN country, the length matches the expected length for that country, and the mod-97 checksum passes. Spaces in the input are stripped automatically — you can enter the IBAN in any grouping.
What this tool does not check: whether the account is active, whether the account belongs to a specific person or institution, or whether the BBAN portion is internally valid per the country's own bank account rules (each country's BBAN has sub-rules that are not universally validated by the IBAN check alone).
Validation runs entirely in your browser — no IBAN is transmitted. For Indian financial ID validation, see the PAN Validator and GST Validator.
How to use this IBAN calculator
- Open the IBAN Validator on this page.
- Type or paste the IBAN into the IBAN field. Spaces between groups of digits are stripped automatically.
- The result badge updates instantly. A green Valid badge confirms the IBAN passes both the country length check and the mod-97 checksum.
- If the badge shows Invalid, the error message specifies whether the country code is unrecognised, the length is wrong, or the checksum fails.
- For a checksum failure, check whether two adjacent digits have been transposed — this is the most common cause.
- Fix the IBAN and the badge updates immediately.
Formula & Methodology
Step 1 — Country and length check: Extract the first two characters as the country code. Look up the expected IBAN length for that country (ranges from 15 characters for Norway to 32 for Saint Lucia). If the lengths do not match, fail. Step 2 — Mod-97 checksum: 1. Move the first 4 characters to the end:NWBK60161331926819GB29for the UK example 2. Replace each letter with its decimal value (A=10, B=11, ..., Z=35) 3. Divide the resulting large integer by 97 4. If the remainder is 1, the IBAN is valid Valid example:GB29 NWBK 6016 1331 9268 19Country: GB (United Kingdom). Expected length: 22. Checksum: 29. Passes mod-97. Result: Valid. Invalid example (wrong length):GB29 NWBK 6016 1331Country: GB. Expected length: 22. Entered length: 18 (without spaces). Result: Invalid — too short.