Sort code and account number to IBAN

Published October 23, 2026

Inside the UK you pay with a sort code and an account number. From abroad, people need your IBAN. The two are the same account written two ways. A UK IBAN has 22 characters: GB, two check digits, a 4-letter bank code, the 6-digit sort code and the 8-digit account number. You can build it yourself, with one catch: the four letters do not come from the sort code.

When you need which

• Paying someone in the UK, from a UK account: sort code and account number. That is what UK banking apps ask for.
• Being paid from another country: give your IBAN. The sender’s bank may also ask for your BIC.
• Paying a UK account from abroad: ask the recipient for their IBAN, not just the sort code.

The IBAN does not replace the sort code. It contains it.

The parts of a UK IBAN

The registry’s own example for the United Kingdom:

Read the other way round, an IBAN gives you the domestic details back. Characters 9 to 14 are the sort code and characters 15 to 22 are the account number. For GB29 NWBK 6016 1331 9268 19 that is sort code 60-16-13 and account 31926819.

The part you cannot guess: the bank code

The four letters after the check digits name the bank. They are the first four letters of its BIC, for example NWBK, BARC, LOYD or HBUK. They are not encoded in the sort code, and there is no formula that turns one into the other. You need them from a source that knows your bank:

• your bank statement or online banking, where the BIC is usually printed next to the IBAN;
• the bank’s own website or helpline;
• the person you are paying, if it is their account.

If you guess the letters, the check digits will still be calculated correctly, and the result will look like a perfect IBAN. It will just not be your IBAN. That is the main trap in converting UK details by hand. Our guide IBAN vs SWIFT/BIC explains how the BIC is built.

Converting step by step

Take a widely used example: bank code WEST, sort code 12-34-56, account number 98765432.

1. Write the national part: bank code, sort code without dashes, account number. WEST 123456 98765432 becomes WEST12345698765432, 18 characters.
2. Add the country code and 00 at the end: WEST12345698765432GB00.
3. Replace each letter by a number (A = 10 … Z = 35): W = 32, E = 14, S = 28, T = 29, G = 16, B = 11.
4. Divide the resulting number by 97. The remainder is 16.
5. Subtract it from 98: 98 − 16 = 82. Those are the check digits.
6. Put it together: GB, 82, then the national part. In groups of four: GB82 WEST 1234 5698 7654 32.

The division in step 4 involves a 28-digit number. Our article on IBAN check digits shows how to do it in pieces. Or let the calculator do it:

Your bank’s statement is the binding source of your IBAN. Calculated from the SWIFT IBAN Registry, updated September 17, 2026. Not a service of any bank. · Disclaimer

The IBAN calculator starts with the United Kingdom selected. It asks for the bank code, the sort code and the account number, and shows the IBAN as you type. Nothing you enter is sent anywhere.

Checking a UK IBAN someone sent you

Paste it into the IBAN checker. It tests five things: the country code, the length (22 for GB), the structure (4 letters, then 14 digits), the check digits and, where a country has one, a national check. The UK has no national check position in the IBAN, so for a GB IBAN the check digits do that job.

Typical errors and what the checker says:

A letter O typed for a zero in the sort code or account part is caught by the structure test, because those 14 positions allow only digits.

What we can and cannot tell you about a sort code

We check that a sort code has six digits and sits in the right place. We do not show which bank or branch a sort code belongs to. There is no free, complete public list of UK sort codes that we could use, and a partial list would give wrong answers. If you need the bank name, ask the person who gave you the details, or your own bank.

A valid result also does not confirm that the account exists or who holds it. UK banks run Confirmation of Payee, a check of the payee’s name against the account, when you set up a payment. If your bank says the name does not match, stop and check before you send money.

Jersey, Guernsey, the Isle of Man and Ireland

The SWIFT IBAN Registry lists Jersey, Guernsey and the Isle of Man under the GB format. Accounts there have GB IBANs with the same 22-character layout.

Ireland looks almost the same but is a different country code: IE, check digits, a 4-letter bank code, the 6-digit sort code (called the NSC, National Sort Code) and an 8-digit account number. Ireland uses the euro, so an Irish IBAN is all a sender in another EU country needs for a euro transfer. See the Irish IBAN page and the UK IBAN page for both formats.

Giving your details to someone abroad

If someone in another country needs to pay you, send them the details in one message, each on its own line, copied from your banking app rather than typed:

• the account holder’s name, exactly as the bank holds it;
• the IBAN in print format, for example GB29 NWBK 6016 1331 9268 19;
• the BIC, if they ask for it;
• the name of your bank.

Do not add your sort code and account number separately unless they ask; both are already inside the IBAN, and two versions of the same account invite mistakes. If you built the IBAN yourself, compare it once with the one your bank shows before you send it.

A quick summary

• UK IBAN = GB + 2 check digits + 4-letter bank code + 6-digit sort code + 8-digit account number = 22 characters.
• The sort code and account number are copied unchanged into the IBAN.
• The 4-letter bank code comes from the BIC, not from the sort code.
• The check digits are calculated with mod 97; never type them from memory.
• Your bank’s IBAN, on your statement or in your app, is the binding one.