IBAN Validation and Formatting

Check whether an IBAN is valid with the international mod-97 algorithm; see the bank for TR IBANs.

Your IBAN is never sent to a server; the check runs in your browser.

What is an IBAN, and how is it validated?

An IBAN (International Bank Account Number) is a standard format designed to identify a bank account uniquely worldwide. In Turkey, an IBAN has 26 characters in total: the "TR" country code (2 characters), a 2-digit check code, a 5-digit bank code, a single fixed digit reserved for future use ("0"), and finally a 16-digit account number. The check digits are mathematically derived from the rest of the IBAN, so a single mistyped digit or two transposed digits — common typing mistakes — can be caught instantly.

How does the mod-97 check work?

The international standard (ISO 7064) moves the IBAN's first 4 characters to the end, converts letters to numbers (A=10, B=11 … Z=35), and computes the remainder of the resulting long number divided by 97. For a valid IBAN, this remainder must always be 1. This tool runs the same algorithm in your browser, computing the remainder digit by digit to avoid large-number overflow. For Turkish IBANs it also matches the bank code against a list of known banks to show which bank it belongs to.

When is this useful?

You'll most often use this tool to check an IBAN copied from an invoice or email for typos before sending money, or to turn a long IBAN you've manually transcribed into a readable, grouped-by-4 format. Keep in mind: a valid mod-97 result only shows that the format is correct — it doesn't prove the account is actually open or that the recipient is the right person; before sending large amounts, confirm the recipient's name through your own bank's verification.

The IBAN standard isn't specific to Turkey; most countries in the SEPA area (Europe) and many other countries use their own IBAN format too — the total character length differs per country (e.g. 22 for Germany, 27 for France), but the check mechanism (mod-97) is the same everywhere. That's why this tool applies the mod-97 check to any IBAN you enter, starting with any country code, not just TR IBANs.

The IBAN you enter never leaves the page; all checking and formatting happens in your browser, with JavaScript.

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Frequently Asked Questions

No. This check only shows that the IBAN is valid in terms of its format/algorithm; it doesn't guarantee the account is open or belongs to the right person. Before sending money, confirm the recipient's name through your bank's own verification.

Yes. The mod-97 check works for every country; the length rules of common countries are also verified separately. The bank-name lookup feature, however, is only for Turkish (TR) IBANs.

The first 2 characters are the country code ("TR"), the next 2 are the check digits, the following 5 characters are the bank's EFT/bank code, the next single character is a fixed reserved digit set aside for future use (usually "0"), and the remaining 16 characters are the account holder's account number within the bank (2+2+5+1+16=26).

It just means that code isn't in this tool's local lookup list — the IBAN itself doesn't have to be invalid. The list covers common banks but doesn't include every up-to-date bank/branch code from the Central Bank (TCMB).

This is the readable presentation format recommended by the IBAN standard (e.g. TR33 0006 1005 1978 6457 8413 26) — it reduces the risk of errors in interbank correspondence and printed documents. The tool offers copying both with and without spaces, since some online forms require the unspaced format.

No. An account number is what your bank assigns you within its own system; an IBAN wraps that account number, together with a bank code and check digits, in an international standard envelope. The same account can have both a classic account number and an IBAN, but domestic transfers and international transfers now use only the IBAN.

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