Is the IBAN the same as my account number?

Your account number is contained inside the IBAN, but the IBAN adds the country code, check digits and bank/branch codes around it, producing a single validated identifier that works across borders.

Are IBANs case-sensitive?

IBANs are always written in upper case. Letters can appear in the country code and, in many countries, inside the BBAN; validators normalise input to upper case and strip spaces before checking.

Can two countries have the same IBAN length?

Yes — length is fixed within a country but not unique across countries. Spain, Sweden and Slovakia all use 24 characters, for example. The country code, not the length, tells you which national format applies.

Guide · 6 min read

What is an IBAN? Structure, check digits and country formats

Last updated 17 July 2026

An IBAN (International Bank Account Number) is a standardised way of writing a bank account number so that it can be validated and routed across borders. Defined by ISO 13616, it is mandatory for SEPA payments and used in 80+ countries worldwide.

The anatomy of an IBAN

Every IBAN follows the same scaffold: a 2-letter ISO country code, 2 check digits, and a country-specific part called the BBAN (Basic Bank Account Number). The BBAN is where countries differ — it encodes the bank code, often a branch code, and the account number in a nationally defined layout.

Take the German example DE89 3704 0044 0532 0130 00: “DE” is the country, “89” are the check digits, “37040044” is the 8-digit Bankleitzahl identifying the bank and branch, and “0532013000” is the account number.

Segment	Length	Purpose
Country code	2 letters	ISO 3166-1 code of the issuing country (IT, DE, FR…)
Check digits	2 digits	ISO 7064 mod-97 checksum over the whole IBAN
BBAN	11–27 chars	Bank code, optional branch code and account number, in a national format

How long is an IBAN?

The length is fixed per country and ranges from 15 characters (Norway) to 31 (Malta). Because the length is deterministic, a wrong-length IBAN can be rejected instantly, before any checksum math.

Shortest: Norway (15), Belgium (16), the Netherlands and Finland (18).
Longest: Malta (31), Cyprus and Poland/Hungary (28).
Most common in the eurozone: 20–27 characters.

What the check digits actually do

The two digits after the country code are not random: they are computed with the ISO 7064 mod-97 algorithm over the entire rearranged IBAN. A single mistyped character makes the checksum fail with a probability above 99%, which is why IBAN validation catches virtually all typos before a payment is even attempted.

Validation is a purely local computation — no registry lookup is needed. That is exactly how the iban2bic API rejects malformed IBANs for free, before any billable resolution happens.

What an IBAN does not contain

An IBAN identifies an account, not the bank’s routing identity on the SWIFT network. It does not contain the BIC, the bank’s name or its address — those must be derived by looking up the bank code embedded in the BBAN against national registries. That derivation is the job of an IBAN-to-BIC service.