IBAN FR Validator

Understanding the French IBAN

An IBAN (International Bank Account Number, standard ISO 13616) identifies a bank account worldwide. It begins with a 2-letter country code, then 2 check digits, then a country-specific BBAN. A French IBAN always has a fixed length of 27 characters and starts with FR.

France belongs to the SEPA zone, so the IBAN is the standard identifier for euro transfers domestically and across borders.

Structure of a French IBAN

After FR and the 2 check digits, the 23-character BBAN is made up of four parts:

• Code banque — 5-digit bank code.
• Code guichet — 5-digit branch code.
• Account number — 11 characters (digits and letters allowed).
• Clé RIB — a 2-digit national check key.

Example: FR14 2004 1010 0505 0001 3M02 606. The older domestic form is the RIB (Relevé d'Identité Bancaire), which bundles these same fields.

How validation works

The IBAN-level check uses the mod-97 algorithm (ISO 7064, MOD 97-10): move the first 4 characters to the end, replace letters with two digits (A=10 … Z=35), read the whole thing as one integer, and confirm that integer mod 97 equals 1. The national clé RIB is a separate domestic check: 97 − ((89×banque + 15×guichet + 3×compte) mod 97).

Common pitfalls

• Forgetting that French account numbers may contain letters — they are part of the 11-character field.
• Counting spaces toward the length: a valid French IBAN is 27 characters without spaces.
• Confusing the clé RIB with the IBAN check digits — they protect different parts.
• Assuming a valid checksum means the account exists: mod-97 only proves structure and check digits.

FAQ

How many characters does a French IBAN have? Exactly 27, starting with FR.

What is the clé RIB? A 2-digit national check key computed from the bank code, branch code and account number.

Does a valid IBAN guarantee the account is real? No. Validation confirms the format and checksum only.