Why does IBAN length differ between countries?

Each country sets its own BBAN (Basic Bank Account Number) format, which varies by how many digits it needs for bank, branch, and account number. Germany uses 22 characters, Norway 15, and Malta 31. The country code and 2 check digits are always the first 4.

What are the first four characters of an IBAN?

The first two letters are the ISO 3166 country code, and the next two digits are the MOD-97 check digits. The rest is the country-specific BBAN. So DE89 means Germany with check digits 89, followed by the German account details.

How does the MOD-97 check work?

Move the first four characters to the end, convert letters to numbers (A=10 ... Z=35), and compute the big number modulo 97. A valid IBAN gives a remainder of 1. Any other remainder means a transcription error.

Does the right length guarantee a valid IBAN?

No. Correct length is necessary but not sufficient. The MOD-97 check digits catch most single-character typos and digit swaps. This tool checks both length and check digits, but only the bank can confirm the account exists.

Should I store IBANs with spaces?

Store them without spaces in a single uppercase string. Spaces in groups of four are a display convention for humans. Always strip whitespace before validating or saving to a database.

What is the IBAN Length by Country?

Reference the exact IBAN character length and structure for every IBAN-participating country, then validate any IBAN's length and MOD-97 check digits in your browser. Includes the BBAN format pattern per country. It runs free in your browser on Gera Tools, with nothing uploaded.

IBAN Length by Country

Name: IBAN Length by Country
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

An IBAN’s length is fixed per country, from 15 characters in Norway up to 31 in Malta. This tool gives the official length and structure for each IBAN-participating country and validates any IBAN you paste against both its length and the MOD-97 check digits.

How it works

Every IBAN starts with the same four characters:

D E 8 9 3 7 0 4 0 0 4 4 0 5 3 2 0 1 3 0 0 0
^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ctry chk BBAN (country-specific)

Characters 1-2 — country code: ISO 3166-1 alpha-2.
Characters 3-4 — check digits: computed with MOD-97.
Remaining — BBAN: the national account number, whose length and layout the country defines.

To validate the check digits, move the first four characters to the end, replace each letter with two digits (A=10 … Z=35), and take the whole number modulo 97. A correct IBAN yields a remainder of exactly 1.

Why IBAN length varies so widely

The variation in length comes entirely from the BBAN — the domestic account number each country had before IBAN was adopted. Some countries had compact national account formats (Norway’s is just 11 digits), while others had elaborate routing structures that needed many more characters to encode bank, branch, and account fields.

For example, Malta’s 31-character IBAN must fit a 4-letter bank code, a 5-digit sort code, and an 18-character account — a legacy of Malta’s banking structure. Norway’s 15-character IBAN encodes an 11-digit domestic account number with no separate bank or branch fields at all. Each country froze its existing domestic format inside the IBAN wrapper.

IBAN lengths for common corridors

Country	Code	Length	BBAN structure
Norway	NO	15	11-digit account
Belgium	BE	16	3-digit bank + 7 digits + 2 check
Netherlands	NL	18	4-letter bank + 10 digits
Finland	FI	18	3-digit bank group + 11 digits
Germany	DE	22	8-digit BLZ + 10-digit Kontonummer
United Kingdom	GB	22	4-letter bank + 6-digit sort + 8 digits
Ireland	IE	22	4-letter bank + 6-digit NSC + 8 digits
Bahrain	BH	22	4-letter bank + 14 alphanumeric
Switzerland	CH	21	5-digit IID + 12-char account
France	FR	27	5-digit bank + 5-digit branch + 11 + 2
Jordan	JO	30	4-letter bank + 4-digit branch + 18
Malta	MT	31	4-letter bank + 5-digit sort + 18

These lengths are set by the SWIFT IBAN Registry and do not change without formal notification.

Practical uses for this reference

Sanity-checking inbound data. If a payment system receives an IBAN, the first automated check should be length against the country code. A 22-character IBAN starting with FR is obviously wrong (France is 27), regardless of whether the checksum passes.
Form validation. Building a payment form that accepts IBANs? The country-length table lets you set the correct maxlength attribute and give the user an immediate hint if their entry is clearly too long or too short.
Debugging wire rejections. When a SWIFT payment bounces with a format error, comparing the received IBAN length against the expected length for its country is a quick first diagnostic step.

Tips and examples

GB (United Kingdom) IBANs are 22 characters: GBkk BBBB SSSS SSAA AAAA AA.
The check digits alone catch most typos, but a wrong country code makes the length check fail first — always confirm the leading two letters.
Strip all spaces and uppercase the string before validating; mixed case or stray spaces are the most common false-failure cause.