IBAN Validator - International Bank Account Checker

About This Tool

Verify any International Bank Account Number (IBAN) with this free validator. Paste an IBAN to check the MOD 97 checksum, verify the country-specific length, validate the structural format, and identify the country and bank. The tool supports over 55 countries from the United Kingdom and Germany to Saudi Arabia and Brazil. Results appear instantly with color-coded pass/fail indicators for each check. Use the example buttons to load sample IBANs from popular countries. A reference table shows the expected IBAN length for common countries so you can spot truncated or padded numbers quickly. Ideal for developers building payment systems, accountants verifying wire transfer details, and anyone receiving international bank information. No data is transmitted or stored. All validation happens on your device.

What Is an IBAN?

An International Bank Account Number (IBAN) is a standardized format for identifying bank accounts across national borders. It was introduced by the International Organization for Standardization (ISO 13616) and the European Committee for Banking Standards to reduce errors in international money transfers.

Every IBAN starts with a two-letter country code, followed by two check digits, and then a country-specific Basic Bank Account Number (BBAN). The BBAN contains the domestic bank code, branch code, and account number. The total length varies by country, ranging from 15 characters (Norway) to 34 characters (some Middle Eastern countries). IBANs are always written in groups of four characters for readability, with the last group being shorter if needed.

How MOD 97 Checksum Verification Works

The MOD 97 algorithm is the mathematical backbone of IBAN validation, defined in ISO 7064. It detects virtually all single-character errors and most transposition errors. The process works as follows:

Move the first four characters (country code + check digits) to the end of the IBAN
Replace each letter with a two-digit number (A=10, B=11, ... Z=35)
Calculate the remainder when dividing the resulting large number by 97
If the remainder equals 1, the IBAN is valid

This tool performs this calculation using an iterative approach that handles the very large numbers involved (IBANs can produce numbers with 40+ digits) without precision loss. The MOD 97 check catches over 99% of accidental errors in IBAN transcription.

Country-Specific IBAN Formats

Each country has a fixed IBAN length and a specific BBAN structure. Some common examples:

United Kingdom (GB): 22 characters. Format: GB + 2 check digits + 4-letter bank code + 6-digit sort code + 8-digit account number
Germany (DE): 22 characters. Format: DE + 2 check digits + 8-digit Bankleitzahl + 10-digit account number
France (FR): 27 characters. Format: FR + 2 check digits + 5-digit bank code + 5-digit branch code + 11-character account number + 2 check digits
Spain (ES): 24 characters. Format: ES + 2 check digits + 4-digit bank code + 4-digit branch code + 2 check digits + 10-digit account number
Netherlands (NL): 18 characters. Format: NL + 2 check digits + 4-letter bank code + 10-digit account number

Common IBAN Errors and How to Fix Them

The most frequent IBAN errors include:

Wrong length: Characters were added or dropped during copy-paste. Compare against the expected length for the country.
Checksum failure: A digit or letter was changed. Re-enter the IBAN carefully from the source document.
Structure error: The IBAN contains lowercase letters, spaces in the wrong positions, or special characters. IBANs should contain only uppercase letters and digits (spaces are formatting only).
Unknown country code: The first two characters do not match any IBAN-issuing country. Verify the country code is correct.

When a checksum fails, the error is almost always a transcription mistake. Ask the sender to provide the IBAN again, preferably by copying it electronically rather than typing it manually.

IBAN vs. SWIFT/BIC Codes

IBANs and SWIFT/BIC codes serve different but complementary purposes. An IBAN identifies a specific bank account, while a SWIFT/BIC code identifies the bank itself. International wire transfers typically require both: the SWIFT code routes the payment to the correct bank, and the IBAN ensures it reaches the right account.

SWIFT codes are 8 or 11 characters long and follow the format: 4 letters (bank code) + 2 letters (country code) + 2 characters (location) + optional 3 characters (branch). For example, NWBKGB2L is the SWIFT code for NatWest Bank in London. The IBAN for an account at that bank would be GB29NWBK60161331926819. Both are needed for a complete international transfer.

Frequently Asked Questions

What does MOD 97 mean?

MOD 97 is a mathematical operation (modulo 97) used to verify IBAN check digits. The full IBAN is converted to a number, divided by 97, and the remainder must equal 1 for the IBAN to be valid. This catches over 99% of transcription errors in a single check.

Do all countries use IBANs?

No. IBANs are primarily used in Europe, the Middle East, and parts of Africa and South America. The United States, Canada, Australia, and most Asian countries do not use IBANs. They use their own domestic account numbering systems. Over 80 countries have adopted the IBAN standard.

Can I validate a US bank account with this tool?

No. The United States does not use IBANs. US bank accounts are identified by a routing number (ABA) and account number. For US domestic transfers, you need the 9-digit routing number and the account number. For international transfers to the US, the sender needs the SWIFT/BIC code and account number.

Why does my IBAN fail the length check?

Each country has a fixed IBAN length. If the length does not match, characters may have been added or dropped during transcription. Check the reference table for the expected length of your country and compare it against your IBAN. Remove any leading or trailing spaces.

Is it safe to enter my IBAN here?

All validation happens on your device. No data is transmitted, stored, or logged. However, you should always be cautious about entering financial information online. For sensitive verification needs, use your bank's official tools or contact them directly.

What is the BBAN part of an IBAN?

The BBAN (Basic Bank Account Number) is the country-specific part of the IBAN that comes after the country code and check digits. It contains the bank code, branch identifier, and account number in a format defined by each country's banking authority. The BBAN structure varies by country.

Can an IBAN pass validation but still be wrong?

It is theoretically possible but extremely unlikely. The MOD 97 checksum catches 99 out of every 100 random errors. However, the validator confirms only the mathematical structure, not that the account exists or belongs to a specific person. Always confirm account details with the intended recipient.