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IBAN Validator

Finance & Global IDs

Check if an IBAN is correctly formatted and passes the mod-97 checksum. Supports 70+ countries — instant result, runs in your browser, no signup needed.

Reviewed by the thecalcu.com team · Last updated June 27, 2026

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.

Why Use an IBAN Validator?

Wire transfer errors caused by a wrong IBAN are expensive to reverse, some banks charge a fee for recall, and the process can take days. A simple format check before submitting a transfer instruction catches the most common errors: a missing character, a transposed digit pair, or copying the IBAN in a format a different bank used (with spaces in different positions).

Common scenarios:

  • Confirming a supplier or vendor's IBAN before setting up a payment run in an accounting system
  • Checking your own IBAN from your bank's app or statement before providing it to a counterparty
  • Building a payment form or treasury system that accepts IBANs and needs to validate the format at entry
  • Reconciling a list of international bank accounts and flagging structurally invalid entries before a batch payment

Who Should Use This Validator?

Finance teams and accounts payable managing international supplier payments who want to confirm IBANs before initiating wire transfers or setting up vendor master data in an ERP.

Developers building payment forms or treasury systems that accept IBANs, validate format and checksum at the point of entry to catch errors before they reach the banking API.

Freelancers and consultants providing their IBAN to international clients who want to confirm they have copied it correctly from their bank app or statement.

Accountants and auditors reviewing a list of payee bank details who want to flag structurally invalid IBANs before a payment run.

What Insights Does the IBAN Validator Give You?

When the IBAN is valid, the tool shows:

  • Country, the two-letter country code
  • Check digits, the two digits at positions 3–4 that encode the mod-97 checksum
  • BBAN, the country-specific bank account portion
  • Length, total character count
  • A note that format validity does not confirm account activity

When the IBAN is invalid, the tool pinpoints the specific failure: unrecognised country code, wrong length for the country, or checksum mismatch (usually a transposed digit).

How to use this IBAN calculator

  1. Open the IBAN Validator on this page.
  2. Type or paste the IBAN into the IBAN field. Spaces between groups of digits are stripped automatically.
  3. The result badge updates instantly. A green Valid badge confirms the IBAN passes both the country length check and the mod-97 checksum.
  4. If the badge shows Invalid, the error message specifies whether the country code is unrecognised, the length is wrong, or the checksum fails.
  5. For a checksum failure, check whether two adjacent digits have been transposed, this is the most common cause.
  6. 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: NWBK60161331926819GB29 for 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 19
Country: GB (United Kingdom). Expected length: 22. Checksum: 29. Passes mod-97. Result: Valid.

Invalid example (wrong length): GB29 NWBK 6016 1331
Country: GB. Expected length: 22. Entered length: 18 (without spaces). Result: Invalid, too short.

Frequently Asked Questions

An IBAN Validator checks whether an International Bank Account Number is correctly formatted and passes the mod-97 checksum verification. IBANs are used for international bank transfers across Europe, the Middle East, and many other countries. This tool validates the country code, the expected length for that country, and the mathematical checksum, confirming the IBAN is structurally correct without connecting to any bank or database.
IBAN stands for International Bank Account Number. It is an internationally agreed-upon standard (ISO 13616) for identifying bank accounts across borders, making cross-border wire transfers more reliable by standardising the account number format. IBANs are mandatory for SEPA transfers within Europe and are widely used for international wires in the Middle East, North Africa, and several other regions. India, the US, and Canada do not use the IBAN system.
An IBAN starts with a two-letter country code (e.g. `GB` for the United Kingdom, `DE` for Germany), followed by two check digits, followed by the BBAN (Basic Bank Account Number), the country-specific account identifier. The total length varies by country: UK IBANs are 22 characters, German IBANs are 22 characters, and French IBANs are 27 characters. Spaces are used for readability (groups of 4) but are stripped before validation.
The mod-97 checksum is the mathematical verification step in IBAN validation. The first 4 characters of the IBAN are moved to the end, all letters are converted to digits (A=10, B=11, ..., Z=35), and the resulting long number is divided by 97. For a valid IBAN, the remainder must be exactly 1. This catches most transposed digits and typos. The check digits (positions 3–4) are chosen at account creation time to make this equation true.
No. This tool validates the format and checksum only. A valid result means the IBAN is structurally correct and mathematically consistent, it does not confirm the account exists, is open, or belongs to any specific person or institution. To verify an account is active, the transfer itself or a bank-specific API call is required.
No. India uses a different system for domestic transfers, the IFSC (Indian Financial System Code) combined with the account number for NEFT and RTGS transfers, and UPI IDs for instant payments. If you are making a transfer from a foreign bank to an Indian account, the foreign bank may ask for the SWIFT/BIC code of the Indian bank and the account number, not an IBAN.
Nothing is sent anywhere. Validation runs entirely in your browser, and the IBAN you enter is never transmitted to a server, never logged, and never stored. You can safely validate your own IBAN or a counterparty's IBAN without privacy concerns.
Over 70 countries use IBANs, including all EU and SEPA member states, the UK, Norway, Switzerland, Turkey, UAE, Saudi Arabia, Kuwait, Qatar, Pakistan, and many others. The US, Canada, Australia, India, China, and Japan do not use IBANs. This tool supports all countries with a registered IBAN format in the ISO 13616 standard.
The BBAN (Basic Bank Account Number) is the country-specific portion of the IBAN, everything after the country code and check digits. In a UK IBAN like `GB29NWBK60161331926819`, the BBAN is `NWBK60161331926819`, which encodes the sort code (`601613`) and account number (`31926819`). The BBAN format differs by country.
Yes. IBAN is conventionally written with spaces in groups of 4 for readability (`GB29 NWBK 6016 1331 9268 19`). This tool strips all spaces before validation, so you can enter the IBAN in any grouping style.
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