About

Incorrect or malformed IBANs in test environments cause silent failures in payment processing pipelines, failed API integrations, and hours of debugging. This generator constructs IBANs that conform to the ISO 13616 standard. Each output carries a valid check digit pair computed via the Modulo 97 algorithm (ISO 7064). The tool covers 80+ country formats with correct BBAN lengths, realistic bank code prefixes, and proper alphanumeric structure. These are syntactically valid IBANs intended for software testing, UI mockups, and data seeding. They do not correspond to real bank accounts. Note: some countries enforce additional national check digits (France uses RIB key, Spain uses two control digits) which this tool approximates but cannot guarantee against live banking infrastructure.

Formulas

Every IBAN is assembled from three components: a 2-letter ISO 3166 country code, a 2-digit check number, and the country-specific Basic Bank Account Number (BBAN). The check digits are computed using the Modulo 97 algorithm defined in ISO 7064.

IBAN = CC + CD + BBAN

Where CC is the country code, CD is the check digit pair, and BBAN is the domestic account structure. The check digit computation proceeds as follows:

S = BBAN + CC + "00"

Each letter in S is converted to its numeric value: A = 10, B = 11, … Z = 35. The resulting numeric string N is then used:

CD = 98 − (N mod 97)

Since N can exceed 30 digits, direct integer computation overflows. The tool uses iterative chunked modulo: process 9 digits at a time, carry the remainder forward. This is mathematically equivalent to full-precision modular arithmetic.

r₀ = 0, r_i+1 = (r_i × 10^k + chunk_i) mod 97

A valid IBAN satisfies: moving the first 4 characters to the end, converting all letters to digits, and computing mod 97 yields exactly 1.

Reference Data

Country	Code	IBAN Length	BBAN Format	Example IBAN
Germany	DE	22	8n + 10n	DE89 3704 0044 0532 0130 00
United Kingdom	GB	22	4a + 6n + 8n	GB29 NWBK 6016 1331 9268 19
France	FR	27	5n + 5n + 11c + 2n	FR76 3000 6000 0112 3456 7890 189
Spain	ES	24	4n + 4n + 2n + 10n	ES91 2100 0418 4502 0005 1332
Italy	IT	27	1a + 5n + 5n + 12c	IT60 X054 2811 1010 0000 0123 456
Netherlands	NL	18	4a + 10n	NL91 ABNA 0417 1643 00
Belgium	BE	16	3n + 7n + 2n	BE68 5390 0754 7034
Switzerland	CH	21	5n + 12c	CH93 0076 2011 6238 5295 7
Austria	AT	20	5n + 11n	AT61 1904 3002 3457 3201
Poland	PL	28	8n + 16n	PL61 1090 1014 0000 0712 1981 2874
Portugal	PT	25	4n + 4n + 11n + 2n	PT50 0002 0123 1234 5678 9015 4
Sweden	SE	24	3n + 16n + 1n	SE45 5000 0000 0583 9825 7466
Norway	NO	15	4n + 6n + 1n	NO93 8601 1117 947
Denmark	DK	18	4n + 9n + 1n	DK50 0040 0440 1162 43
Finland	FI	18	3n + 11n	FI21 1234 5600 0007 85
Ireland	IE	22	4a + 6n + 8n	IE29 AIBK 9311 5212 3456 78
Luxembourg	LU	20	3n + 13c	LU28 0019 4006 4475 0000
Czech Republic	CZ	24	4n + 6n + 10n	CZ65 0800 0000 1920 0014 5399
Romania	RO	24	4a + 16c	RO49 AAAA 1B31 0075 9384 0000
Greece	GR	27	3n + 4n + 16c	GR16 0110 1250 0000 0001 2300 695
Hungary	HU	28	3n + 4n + 1n + 15n + 1n	HU42 1177 3016 1111 1018 0000 0000
Croatia	HR	21	7n + 10n	HR12 1001 0051 8630 0016 0
Bulgaria	BG	22	4a + 4n + 2n + 8c	BG80 BNBG 9661 1020 3456 78
Slovakia	SK	24	4n + 6n + 10n	SK31 1200 0000 1987 4263 7541
Slovenia	SI	19	5n + 8n + 2n	SI56 2633 0001 2039 086
Lithuania	LT	20	5n + 11n	LT12 1000 0111 0100 1000
Latvia	LV	21	4a + 13c	LV80 BANK 0000 4351 9500 1
Estonia	EE	20	2n + 2n + 11n + 1n	EE38 2200 2210 2014 5685
Cyprus	CY	28	3n + 5n + 16c	CY17 0020 0128 0000 0012 0052 7600
Malta	MT	31	4a + 5n + 18c	MT84 MALT 0110 0001 2345 MTLC AST0 01S

Frequently Asked Questions

No. The IBANs are syntactically valid per ISO 13616 and will pass Mod-97 check digit validation, but the underlying bank codes and account numbers are randomly generated. They do not correspond to any real financial institution account. Use them exclusively for software testing, UI prototyping, database seeding, and documentation examples.

An IBAN can be up to 34 characters. When letters are converted to two-digit numbers (A=10 through Z=35), the resulting numeric string can exceed 50 digits. JavaScript's Number type loses precision beyond 2^53 (roughly 16 digits). The generator uses iterative chunked modulo arithmetic, processing 9 digits at a time and carrying the remainder, which is mathematically equivalent to computing the modulo of the full number. BigInt is used as a secondary verification where available.

The ISO 13616 check digits (positions 3-4) are always correctly computed. Some countries embed additional national check digits within the BBAN structure. For example, France uses a 2-digit RIB key, and Spain uses two control digits. This generator includes approximate national check digit logic for the most common countries (FR, ES, BE, PT, NO, FI) but does not guarantee national-level validity for all 80+ supported countries.

For the 30 most common countries, the generator draws from a curated pool of real-world bank code prefixes (e.g., NWBK, BARC, DEUT). This means the bank identifier portion looks realistic. For less common countries, random alphanumeric codes matching the correct format and length are generated. The account number portion is always randomized.

They are suitable for format validation testing - confirming your system correctly parses IBAN length, structure, and check digits. However, most payment gateways (Stripe, Adyen) provide their own dedicated test IBANs that trigger specific response codes (success, insufficient funds, etc.). Use this generator for volume testing and edge-case coverage, and refer to your gateway's documentation for functional test accounts.

Each IBAN in the batch is independently assigned a random country from the full supported list. This produces a diverse, multi-country dataset useful for testing international payment routing, IBAN formatting display logic, and multi-locale validation. The country distribution is uniform - each country has equal probability of selection per IBAN.