UK IBAN — format, length, example & validator

How a UK IBAN is structured

A United Kingdom IBAN is read left to right in three blocks. The first two characters are the ISO 3166 country code GB, which tells the receiving bank the account is in United Kingdom. The next two characters are MOD 97-10 check digits that protect against typos. The remaining 18 characters form the BBAN (Basic Bank Account Number), which United Kingdom splits into 3 fields: 4 letters, then 6 digits, then 8 digits. Because the BBAN layout is fixed for United Kingdom, the validator can check both the total length (22 characters) and the internal structure of every GB IBAN.

UK IBAN example

Below is a sample United Kingdom IBAN that passes all three validation layers (character set, 22-character length, and MOD 97 check digits). It is a synthetic test value for integration testing and form demos — never send money to it. The breakdown shows how the GB country code, check digits, and BBAN fields fit together for a real United Kingdom account.

Common UK banks and IBAN format examples

Bank names and BICs help you identify the receiving institution, but they do not change the national IBAN layout. A UK IBAN always has 22 characters and follows 4!a6!n8!n; the bank identifier is embedded in the first BBAN field shown in the table below. The three commonly encountered banks listed here are useful starting points when you are checking payment instructions: Barclays Bank, HSBC Bank plc, HSBC UK Bank. Always copy the exact IBAN and BIC supplied by the beneficiary, because a bank can use different codes for its head office, a regional office, or a specialist payment branch. The examples are deliberately synthetic format fixtures. GB29NWBK60161331926819 demonstrates the country length and checksum, but it is not an account at Barclays Bank or any other bank. A real UK IBAN example must come from the account holder or the bank's own statement. Never infer an account number by combining a public BIC with random digits: that can pass a mathematical checksum while still pointing to no account, or to the wrong beneficiary. When a payment form asks for a UK IBAN, enter the two-letter country prefix and check digits exactly as issued, remove display spaces if the form requires a continuous value, and verify the beneficiary name. Compare the total length (22) and the BBAN field boundaries with the pattern on this page. If the receiving bank gives you an 8-character BIC, do not append a branch suffix yourself; if it gives an 11-character BIC, preserve all three branch characters. For high-value transfers, ask the bank to confirm whether it wants a head-office BIC or a branch-specific BIC before submitting the wire. The most common UK formatting traps are copying a domestic account number instead of the IBAN, dropping leading zeroes in a bank or account field, and mistaking a visually similar country prefix. Spaces are harmless when this site's checker cleans input, but they may count as characters in older payment portals. A structurally valid result only proves the ISO 13616 format and MOD 97 check digits; it does not prove that the account exists or that the beneficiary details are correct. Validate first, then confirm the full payment instruction with the recipient's bank.

For an inbound international transfer, request four pieces of information from the beneficiary: the legal account name, the complete UK IBAN, the receiving bank's BIC/SWIFT code, and the bank's address if the sending portal asks for it. Start by validating the IBAN without changing any characters. The first two letters must be GB; the next two digits are check digits, not part of the domestic account number. Then compare the 22-character length and the BBAN fields. A payment can be rejected when a sender enters a domestic clearing code in the IBAN field, leaves out a leading zero, or pastes a BIC into the account-number field. If the form offers separate fields for bank code, branch code, and account number, follow the bank's instructions rather than splitting the IBAN by guesswork. The pattern 4!a6!n8!n is a validation guide, not permission to manufacture account data. Some banks route international payments through a central office even when the beneficiary uses a local branch; others require a branch-specific BIC. Confirm the routing choice with the recipient before sending, and keep a copy of the submitted value so support staff can trace a rejected transfer. For recurring payments, store the normalized IBAN (uppercase letters, no spaces) and display it in groups of four for humans. Revalidate after any edit, because one changed character alters the MOD 97 remainder. If the checker reports a valid result but the bank rejects the transfer, contact the bank: format validation cannot see sanctions screening, account status, currency restrictions, name matching, or correspondent-bank requirements. These operational checks are why a careful payment workflow uses both an IBAN checker and the bank's official instructions.

How UK IBAN check digits work

The two check digits at positions 3–4 of a United Kingdom IBAN are computed with the MOD 97-10 algorithm defined by ISO 13616. To verify them, the IBAN is rearranged so the BBAN comes first and the country code plus check digits go last, letters are converted to numbers (A = 10, B = 11, …, Z = 35), and the resulting large integer is divided by 97. A valid GB IBAN always leaves a remainder of 1. This single check catches every single-digit typo and most adjacent-digit swaps, which is why a one-character mistake is enough to make a United Kingdom IBAN fail validation instantly — and why you should always validate before wiring money.

UK IBAN and SWIFT codes

To receive an international wire into United Kingdom, the sender usually needs both your IBAN and the SWIFT/BIC code of your bank. The IBAN identifies your account; the SWIFT code identifies the bank. Once you have validated your GB IBAN on this page, look up the receiving bank's SWIFT code on the United Kingdom SWIFT codes page to complete the wire instructions.

UK IBAN FAQ

How long is a United Kingdom IBAN?

A United Kingdom IBAN is always 22 characters long: 2 letters for the country code (GB), 2 MOD 97 check digits, and a 18-character BBAN. Any United Kingdom IBAN that is shorter or longer than 22 characters is invalid.

What country code does a United Kingdom IBAN start with?

A United Kingdom IBAN starts with the ISO 3166 country code GB. The first two characters are always GB, followed by two check digits, then the country-specific BBAN.

How do I validate a United Kingdom IBAN?

Paste the IBAN into the validator on this page — it checks the character set, the 22-character length, and the MOD 97 check digits, all in your browser. You can also load the worked example to see a valid GB IBAN pre-filled.

Does a valid United Kingdom IBAN mean the account exists?

No. Validation only confirms the IBAN is structurally well-formed and the check digits are correct per ISO 13616. It does not verify the account exists, is open, or belongs to anyone. Always confirm with the recipient or their bank before sending money.

What is the BBAN structure for United Kingdom?

The United Kingdom BBAN is 18 characters and follows the ISO 13616 pattern 4!a6!n8!n: 4 letters (A–Z), then 6 digits (0–9), then 8 digits (0–9). The BBAN layout is fixed for United Kingdom, so the validator can check the internal structure of every GB IBAN, not just the total length.

Do I need a SWIFT code as well as an IBAN for United Kingdom?

For most cross-border transfers into United Kingdom you need both: the IBAN identifies the account, and the SWIFT/BIC code identifies the bank. Validate the GB IBAN here, then look up the bank's SWIFT code separately.