How long is an IBAN from the United Kingdom?

22 characters, written in groups of four on paper (GB35 ABCD 5678 9012 3456 78 as a synthetic example).

Can I find the bank from the IBAN?

The bank identifier is the 4 characters at positions 5–8; the bank’s name and BIC are in SWIFT’s licensed directory, which the API does not resolve.

Does a valid IBAN mean the account exists?

No. The check digits and the structure say the IBAN is well formed; existence and ownership are known to the bank only, at payment time.

United Kingdom IBAN format

An IBAN from the United Kingdom is 22 characters long: the country code GB, two check digits, then 4 letters (bank code), 6 digits (branch code), 8 digits (account number). The United Kingdom is in SEPA. Length and structure from the SWIFT IBAN Registry (ISO 13616), transcribed 2026-10-24; the SEPA flag from the EPC list.

Published 2026-10-28

Structure

22 characters in all. Registry notation of the BBAN: 4!a6!n8!n (n digits, a upper-case letters, c alphanumerics, ! fixed length).

Position	Length	Characters	Meaning
1–2	2	letters	country code GB
3–4	2	digits	check digits (ISO 7064 mod 97-10)
5–8	4	letters	bank code
9–14	6	digits	branch code
15–22	8	digits	account number

Example

GB35 ABCD 5678 9012 3456 78 is a synthetic example: placeholder characters in every part, with the check digits computed so that the mod-97 test passes. It is not a real account and no bank issued it; use it to test an input field, not to pay.

SEPA

The United Kingdom is in the geographical scope of the SEPA schemes: a euro credit transfer to this IBAN costs the same as a domestic one and arrives within one business day (seconds with SCT Inst).

Check one

The API checks the characters, the country, the length (22), the mod-97 check digits and the BBAN pattern, and returns the bank and branch identifier.

curl — validate an IBAN from the United Kingdom

curl "https://veriport.io/api/v1/iban/validate?iban=GB35ABCD56789012345678"

Questions

How long is an IBAN from the United Kingdom?: 22 characters, written in groups of four on paper (GB35 ABCD 5678 9012 3456 78 as a synthetic example).
Can I find the bank from the IBAN?: The bank identifier is the 4 characters at positions 5–8; the bank’s name and BIC are in SWIFT’s licensed directory, which the API does not resolve.
Does a valid IBAN mean the account exists?: No. The check digits and the structure say the IBAN is well formed; existence and ownership are known to the bank only, at payment time.

Free: five checks, bank identifier, SEPA flag.

Check an IBAN

Sources

IBAN Registry (ISO 13616) — country lengths, BBAN structures, SEPA membership — SWIFT, ISO 13616 registration authority, consulted 2026-10-24. Transcribed from the public registry; the release number in force on the day checkout opens must be written on the IBAN docs page (owner step).
ISO 13616-1:2020 — Financial services — International bank account number (IBAN): structure and mod 97-10 check (ISO/IEC 7064) — ISO, consulted 2026-10-24
EPC list of SEPA scheme countries (geographical scope of the SEPA schemes) — European Payments Council, consulted 2026-10-24. The 2025 additions (Albania, Moldova, Montenegro, North Macedonia, effective 5 October 2025) are flagged `sepaSince` on the row.