IBAN Validator

How this calculator works

This browser-based tool helps you make a first, transparent estimate from the values you provide. Enter the figures in the fields and the result updates as you edit them. JavaScript performs the calculation on your device; the calculator does not send your salary, property, vehicle or account details to a calculation server. Keep supporting documents secure and only enter sensitive figures on a device you trust.

Formula, assumptions and limits

Validate an IBAN format and MOD-97 checksum in your browser. Rates and eligibility can depend on tax year, residence, transaction details and individual circumstances. UK income tax, National Insurance and SDLT follow separate rules; SDLT applies in England and Northern Ireland, while Wales and Scotland have different property-tax systems. Check current official guidance before acting.

Do not rely on a rounded estimate for a tax return, payment or legal decision. Compare it with official notices, current rate tables and professional advice where needed. Real-world outcomes may include additional reliefs, fees, rate changes or personal circumstances that a simple calculator cannot represent. Your entries are not saved and are discarded when you close the tab.

Use the output as a planning aid: verify each input, read the assumptions and adjust the figures when your circumstances differ. If an important detail is uncertain, contact the relevant authority or a qualified tax, legal or financial professional.

Before acting, check your inputs, tax year and jurisdiction. Note the assumptions used, compare the result with records and official guidance, and recalculate when rules or your circumstances change.

Understanding IBAN country formats and checksums

An IBAN contains a two-letter country code, two check digits and a country-specific Basic Bank Account Number. The validator removes spaces, checks the allowed characters and compares the total length with the known format for that country. It then moves the first four characters to the end, converts letters to numbers and calculates the remainder modulo 97. A remainder of one means the structure and checksum are plausible. It does not prove that an account exists, is open or belongs to the intended recipient. No bank lookup is made and the entered value is processed in your browser.

The BBAN structure varies by country. A German IBAN encodes the bank routing code and account number in a defined arrangement, while other countries use different bank or branch identifiers. A BIC cannot be reliably derived from every IBAN alone. Compare the number with a trusted invoice or bank confirmation and use a secure channel when sharing payment details. Check digits catch many typing errors, but they do not prevent fraud or identify a correctly formatted wrong beneficiary. This page does not initiate a transfer or verify the payee. Treat a valid checksum as one formatting check, and independently confirm any change to supplier bank details before sending money.

Frequently asked questions