Technical Specification

Complete IBAN Structure & Format Specification

A comprehensive breakdown of international IBAN structure rules, character limits, national BBAN formats, and checksum positioning.

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Global IBAN Format Standards

An International Bank Account Number is structured according to the ISO 13616 standard. While maximum length is restricted to 34 characters, every country defines its exact rigid character length and internal block arrangement.

IBAN Structure Breakdown

Component	Length	Description
Country Code	2 chars	ISO 3166-1 alpha-2 country identifier (e.g., DE, FR, GB)
Check Digits	2 numbers	ISO 7064 MOD-97 checksum (02 to 98)
Basic Bank Account Number (BBAN)	Up to 30 chars	National bank code, branch code, and account number

Selected Country Length & Regex Reference

Country	Length	Example Format
Germany (DE)	22 chars	`DEkk bbbb bbbb cccc cccc cc`
Austria (AT)	20 chars	`ATkk bbbb bccc cccc cccc`
Switzerland (CH)	21 chars	`CHkk bbbb cccc cccc ccc c`
France (FR)	27 chars	`FRkk bbbb gggg cccc cccc ccc ccc`
United Kingdom (GB)	22 chars	`GBkk bbbb ssss sscc cccc cc`

Example IBAN Decomposition

Examining German sample IBAN DE89370400440532013000:

DE: Country code
89: Check digits
37040044: Bank code (Bankleitzahl / BLZ)
0532013000: Account number (Kontonummer)

Frequently Asked Questions

Why do different countries have different IBAN lengths?

Because each country integrated its pre-existing legacy domestic bank account numbering system into the ISO 13616 standard.

Are spaces allowed in IBANs?

Human-readable displays often group IBANs in blocks of 4 characters separated by spaces. However, digital validation APIs automatically strip all whitespace before processing.

How can I validate these structures programmatically?

Our IBAN Validation API automatically enforces correct length and regex rules for all 100+ supported countries.

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