🏦 IBAN Validator & Formatter
Paste an IBAN to check its ISO 13616 checksum and length and format it correctly, the number never leaves your device.
ISO 13616 mod-97 check passed
How the iban validator & formatter works
An IBAN carries its own checksum. The tool moves the first four characters (country code + two check digits) to the end, converts every letter to two digits (A=10 … Z=35), and takes the whole number modulo 97, a valid IBAN gives a remainder of exactly 1. It also verifies the length against the fixed length for that country (where known) and formats the IBAN in the standard groups of four.
This checks structure and the check digits only. It confirms an IBAN is well-formed and not mistyped, not that the account exists or is open. That is exactly what you want before saving a payee or sending a payment: catching a transposed digit locally, without sending the account number to a third-party server.
Frequently asked questions
How is an IBAN validated?
By the ISO 13616 mod-97 checksum: rearrange so the country code and check digits move to the end, replace letters with numbers (A=10 … Z=35), and compute the whole value modulo 97, a valid IBAN yields 1. This tool also checks the country-specific length.
Does this confirm the bank account exists?
No. It validates the format and check digits only, which catches typos and transpositions. Whether the account is real and open can only be confirmed by the bank during a payment.
Why is my IBAN flagged as the wrong length?
Each country has a fixed IBAN length (Germany 22, UK 22, France 27, and so on). A different length means a digit is missing or extra, re-check the number against your bank statement.
What do the parts of an IBAN mean?
The first two letters are the ISO country code (GB, DE, FR…), the next two are the check digits, and the rest is the country-specific BBAN, typically a bank/branch code plus the account number. GB82 WEST 1234 5698 7654 32, for instance, is a UK IBAN whose WEST is the bank identifier.
Why convert letters to numbers in the checksum?
The mod-97 algorithm operates on a pure number, so every letter is mapped to a two-digit value (A=10, B=11 … Z=35) before the modulo is taken. This is what lets a single formula validate IBANs from any country regardless of the letters in the country code or BBAN.
Is my IBAN uploaded anywhere?
No, the checksum runs in your browser, so the account number stays on your device. It works offline.