UK IBAN number: what it looks like and how it is built

IBAN number UK: verified on the bank's own page

Ordering is a printed rule, not a rating: banks with more verified identifiers first, then alphabetically. Nothing here is ranked by how good a bank is.

Download the IBAN number UK dataset (CSV), free to reuse with citation.

The parts, in order

Twenty-two characters for a UK IBAN, in four blocks. Monzo's breakdown names them from the middle outwards: the four-letter bank code, then "123456 – sort code: the next six numbers are your standard domestic sort code", then "12345678 – account number: the final eight numbers are your standard domestic bank account number". The country code GB and two check digits sit in front.

The Co-operative Bank lists the same structure from the other direction: "country code - identifies which country the IBAN was issued and where the account is held", a "check number" that "helps a banking institution to validate an IBAN", a bank identifier, and then "sort code & account number".

The two check digits are the only part you cannot type from memory. They are computed from the rest of the number under the ISO 13616 mod-97 rule, which is why a single mistyped digit anywhere in an IBAN almost always fails validation instead of quietly reaching the wrong account.

IBANs are mandatory in the European Economic Area and optional or unused elsewhere. The United States does not use them at all, which is why a US supplier asking you for your IBAN can accept one from you but cannot give you theirs.

Questions people ask

Where do I find my UK IBAN?

Your bank generates it rather than issuing it separately. Nationwide says: "You can find your IBAN on your monthly account statement. Or you can use the app and internet bank." Starling points customers to the app: "Account details" and then "International".

Is IBAN number the right phrase?

Strictly no, and Monzo says so: the N already stands for number. It is the phrase almost everyone searches, so it is the phrase used here, but you will see banks write simply IBAN.

Can I build my IBAN myself from my sort code?

The structure is public and the arithmetic is public, so in principle yes. In practice use your bank's own generator or app: the four-letter bank code differs between brands that share a banking licence, and getting it wrong produces a number that validates and still fails.