# Free BBAN to IBAN Converter & National Account Calculator
> Convert national Basic Bank Account Numbers (BBAN) and local clearing codes (Sort Codes, BLZ, RIB) into fully compliant international IBANs with calculated MOD-97 check digits.

- **Canonical URL:** https://stanzaapi.com/tools/iban-validator/converter/bban-to-iban
- **Governing Standard:** ISO 13616 / ISO 7064 MOD-97-10 (SWIFT & ISO 13616 IBAN Registry)
- **Edge Latency SLA:** <1ms Edge (Cloudflare V8 Isolates)
- **Execution Model:** Pure compute $f(x) = y$, 100% In-Memory (Zero Store, Zero Log)

## Technical Overview & Governing Rules
Transforms domestic bank account formats into international ISO 13616 standard representations.

Computes the two-digit ISO 7064 MOD-97 check digits automatically by appending the 2-letter country code + "00", converting to integer representation, and calculating 98 - (N mod 97).

Validates domestic BBAN structure against national clearing house standards before generating the international identifier.

## Specification Matrix
| Country | Domestic Components | IBAN Construction Assembly |
| --- | --- | --- |
| Germany (DE) | Bankleitzahl (8 digits) + Kontonummer (10 digits) | DE + CheckDigits + BLZ (8) + KTO (10, zero-padded) |
| United Kingdom (GB) | Sort Code (6 digits) + Account Number (8 digits) | GB + CheckDigits + BankCode (4 letters) + Sort (6) + Account (8) |
| France (FR) | Code Banque (5) + Code Guichet (5) + Numéro Compte (11) + Clé (2) | FR + CheckDigits + Banque (5) + Guichet (5) + Compte (11) + Clé (2) |
| Netherlands (NL) | Bank Identifier (4 letters) + Rekeningnummer (10 digits) | NL + CheckDigits + Bank (4) + Account (10, zero-padded) |

## Standard JSON Response Model
```json
{
  "valid": true,
  "iban": "GB29MIDL40051512345678",
  "countryCode": "GB",
  "countryName": "United Kingdom",
  "sepa": true,
  "bankCode": "MIDL",
  "branchCode": "400515",
  "accountNumber": "12345678",
  "checksumValid": true
}
```

## Frequently Asked Questions & Edge Cases
### Q: What is the difference between BBAN and IBAN?
**A:** A BBAN (Basic Bank Account Number) is the domestic account number used within a specific country. An IBAN (International Bank Account Number) prefixes the BBAN with the country code and two MOD-97 check digits to ensure global uniqueness and error-free routing.