United Kingdom IBAN validator
How the IBAN format works
- Format
- GB + 2 check digits + 4 bank letters + 14 digits
- Example
- GB82WEST12345698765432
Things to watch for
- 22 characters total
- Bank code is 4 letters
^GB[0-9]{2}[A-Z]{4}[0-9]{14}$A UK IBAN is the 22-character international version of the sort code and account number every UK bank customer already has: “GB”, two check digits, a 4-letter bank code, your familiar 6-digit sort code, and your 8-digit account number, all run together with no spaces in the machine-readable form (spaces on paper are just for readability). Anyone sending or receiving a SEPA transfer, invoicing a customer in the EU, or filling in an international payment form that asks for an IBAN instead of a sort code and account number needs to get this right — most UK banking apps show the IBAN alongside your normal account details if you don’t already have it written down.
How this validator works
This tool checks the “GB” prefix, confirms the bank code block is 4 letters, the sort code block is 6 digits, and the account number block is 8 digits, then runs the real mod-97 checksum (ISO 7064) UK banks use to generate valid IBANs — entirely in your browser. Nothing is sent to a server, there’s no signup, and the result appears the moment you stop typing. The bank code letters aren’t arbitrary: they’re the same four letters your bank uses in SWIFT/BIC messages — in the example above, WEST is the bank code, immediately followed by the 6-digit sort code and 8-digit account number.
What a pass doesn’t tell you
A pass here confirms the IBAN is correctly formed and internally consistent — not that the account exists, is open, or belongs to whoever you think it does. This tool does no bank-name lookup and makes no contact with any bank or clearing system; it’s a pure client-side structure and checksum check. If a number you typed fails, the most common cause is a transposed digit inside the sort code or account number block — re-check it against your bank statement or banking app before assuming the IBAN itself is wrong.
Scope: this page and tool cover UK IBAN structure and mod-97 checksum validation only — not payment processing, bank-name resolution, or confirming an account is active, none of which a client-side check can tell you. Use this validator to catch a typo before a transfer fails; use your bank to confirm the account itself.
Content last reviewed 2026-07-07.
IBAN FAQ
What does a UK IBAN look like?
It's 22 characters: 'GB', two check digits, a 4-letter bank code, your 6-digit sort code, and your 8-digit account number — for example GB82WEST12345698765432. Banking apps usually display it with spaces every four characters for readability; the underlying value has none.
Does a successful check mean the account is real and open?
No. This tool only confirms the IBAN is correctly formatted and passes the mod-97 checksum — it does no bank-name lookup and never contacts a bank. To confirm an account is active, ask the account holder or use your bank's own payment verification.
Where do I find my UK IBAN?
Your sort code and account number are already most of it. Check your banking app or a recent statement, which usually shows the full IBAN directly, or ask your bank to generate it from your existing sort code and account number.