IBAN Validator — Free Online Verification Tool

How to Use the IBAN Validator

This tool provides instant IBAN validation using the official MOD-97 algorithm specified in ISO 13616. Whether you are verifying a payment recipient's bank details, checking an IBAN you received on an invoice, or setting up recurring international transfers, follow these steps.

1. Enter the IBAN number. Type or paste the IBAN into the input field. You can include spaces for readability or enter the number as a continuous string; the validator handles both formats. The input automatically converts to uppercase, so you can enter lowercase characters without issue. IBANs are printed on bank statements, debit cards, and online banking portals.
2. Check the validation result. A green checkmark and "Valid IBAN" message means the number passes all validation checks. A red cross and "Invalid IBAN" message indicates an error. If the IBAN is invalid, check for typos, missing digits, or transposed characters. Even a single incorrect digit will cause validation to fail.
3. Review the details. The results show the identified country and country code, the check digits, the BBAN (domestic account number portion), the actual versus expected length, and the properly formatted IBAN with standard four-character grouping. Use the formatted version when providing your IBAN to others.

For batch validation of multiple IBANs (common in payroll processing or accounts payable), validate each number individually through this tool or consider implementing the MOD-97 algorithm in your accounting software.

Understanding the IBAN Validation Algorithm

IBAN validation uses a precise mathematical process defined by ISO 13616. The algorithm catches virtually all single-digit errors and most transposition errors, making it extremely reliable for payment verification.

IBAN Structure

MOD-97 Validation Algorithm

The step-by-step process:

1. Step 1: Remove all spaces from the IBAN
2. Step 2: Move the first four characters to the end of the string
3. Step 3: Convert each letter to a two-digit number (A=10, B=11, ..., Z=35)
4. Step 4: Divide the resulting large number by 97
5. Step 5: If the remainder is 1, the IBAN is valid

Validation Example

Validate GB29 NWBK 6016 1331 9268 19:

1. Remove spaces: GB29NWBK60161331926819
2. Rearrange: NWBK60161331926819GB29
3. Convert letters: N=23, W=32, B=11, K=20, G=16, B=11 gives: 23321120601613319268191629
4. Compute MOD-97: 23321120601613319268191629 mod 97 = 1
5. Result: Remainder is 1, so the IBAN is valid

The algorithm processes the large number in chunks to avoid integer overflow in programming implementations. Each chunk is computed as (previous remainder * 10^(chunk length) + chunk value) mod 97.

Practical IBAN Validation Examples

These scenarios demonstrate why IBAN validation matters in everyday business and personal international transactions.

International Invoice Payment

Rebecca, a procurement manager, receives an invoice from a German supplier with the IBAN DE89 3704 0044 0532 0130 00. Before initiating the wire transfer of 45,000 EUR, she validates the IBAN. The validator confirms it is valid: country is Germany, check digits are 89, length is 22 (correct for DE), and the bank code 37040044 identifies the bank. By validating before sending, Rebecca avoids the potential $50-75 bank fee for a rejected international transfer and the 5-10 business day delay of a returned payment.

Freelancer Setting Up Payment Details

Ahmed, a freelance designer in the Netherlands, needs to provide his IBAN to clients. He checks NL91 ABNA 0417 1643 00 through the validator to ensure he has the correct number before sharing it on invoices. The validator confirms it is valid with the Netherlands country code, check digits 91, and 18-character length (correct for NL). This prevents embarrassing situations where a typo in the IBAN leads to failed client payments and delayed income.

Detecting a Fraudulent IBAN

Sofia, an accounts payable specialist, receives an email appearing to be from a regular supplier requesting a change of bank details to FR76 3000 6000 0112 3456 7890 188 (note: the last digit is wrong). She validates the IBAN and finds it invalid: the check digit verification fails. This flags a potential payment redirection fraud attempt. She contacts the supplier through a verified phone number and confirms the email was fraudulent. The IBAN validator served as an additional security layer, catching an error that could have resulted in a significant financial loss.

Payroll Processing for International Employees

Chen manages payroll for a company with 25 employees across Europe. Each month, he validates all employee IBANs before submitting the payroll batch. When employee #17's IBAN ES91 2100 0418 4502 0005 1332 validates correctly but employee #22's IBAN IT60 X054 2811 1010 0000 0123 456 returns invalid (incorrect length for Italy, which requires 27 characters), he catches the error before submission. Correcting the IBAN before processing saves the company failed transfer fees and ensures all employees receive their salary on time.

IBAN Validation Tips and Complete Guide

Properly handling IBANs is essential for anyone involved in international banking, whether you are a business processing cross-border payments, an individual sending money abroad, or a developer building payment systems.

Always Validate Before Sending

Never initiate an international wire transfer without first validating the recipient's IBAN. Failed transfers due to invalid IBANs cost $25-75 per occurrence in bank fees and can take 5-10 business days to resolve. For businesses processing hundreds of international payments monthly, implementing IBAN validation as a mandatory step in the payment workflow saves thousands of dollars annually and eliminates payment delays that strain supplier relationships.

Know the Country-Specific Formats

IBAN lengths and internal structures vary by country. German IBANs are always 22 characters, while French IBANs are always 27. If someone provides an IBAN that does not match the expected length for the country code, it is incorrect even if the check digits happen to validate. This country-specific length check is the fastest way to spot an invalid IBAN before running the full MOD-97 algorithm.

Be Aware of IBAN Fraud Schemes

IBAN-related fraud is increasingly common. Scammers intercept legitimate business emails and change the IBAN in invoices or payment instructions to redirect funds to their own accounts. To protect against this: always validate any new or changed IBAN, confirm bank detail changes through a separate verified communication channel (phone call, in-person), and implement dual-authorization for any changes to stored bank details. Some banks offer IBAN-to-name verification services that cross-check the IBAN against the account holder's name.

Use Proper Formatting for Readability

IBANs should be printed and displayed in groups of four characters separated by spaces (e.g., GB29 NWBK 6016 1331 9268 19). This formatting makes it easier to read, transcribe, and verify the number. However, when transmitting IBANs electronically (in payment files, APIs, or databases), always use the compact format without spaces. This tool accepts both formats and displays the properly formatted version in the results.

Common Mistakes to Avoid

• Confusing IBAN with regular account numbers. A regular domestic bank account number is not an IBAN. IBANs include the country code and check digits as prefix. Sending money using a domestic account number format to an international transfer will fail in countries that require IBAN.
• Transposing digits when copying. Manually copying long IBANs is error-prone. Always copy-paste when possible and validate after pasting. The MOD-97 algorithm catches most transposition errors, but it is better to avoid them in the first place.
• Assuming validation means the account exists. A valid IBAN format does not guarantee the account is active or belongs to the intended recipient. IBAN validation checks mathematical correctness, not account existence. Some banks offer additional services to verify account ownership.
• Using outdated IBAN formats. Some countries have updated their IBAN formats over the years. Always ensure you are using the current format specification. This tool stays updated with the latest ISO 13616 standards.
• Not validating IBANs in your own systems. If you develop software that processes IBANs, implement MOD-97 validation on input. Storing and processing unvalidated IBANs propagates errors downstream and increases the rate of failed payments.