France · Validation
France SIRET & SIREN validator.
Check the Luhn check digit of a French SIREN (9 digits) or SIRET (14 digits). Validateur de numéro SIRET / SIREN : contrôle de la clé de Luhn, avec l’exception La Poste. Runs entirely in your browser.
Inputs
Result
Enter a SIRET or SIREN and press Validate.
How the SIREN and SIRET check digit works
A SIREN identifies a French legal entity (9 digits). A SIRET identifies one of its establishments: the 9-digit SIREN followed by a 5-digit NIC (numéro interne de classement), 14 digits in all. The last digit of each is a Luhn check digit.
- Starting from the right, double every second digit; if a doubled digit is over 9, subtract 9.
- Add all the digits together.
- The number is consistent when the total is a multiple of 10. For a SIREN this runs over the 9 digits; for a SIRET, over all 14.
- La Poste exception: all establishments of La Poste share SIREN 356000000. Their SIRET are valid when the sum of the 14 digits is a multiple of 5 instead. The head office, 356 000 000 00048, follows the normal Luhn rule.
Worked example: 732 829 320 00074 gives a Luhn total divisible by 10, so it passes; changing the last digit to 9 (73282932000079) fails.
En français
Le SIREN compte 9 chiffres et identifie l’entreprise ; le SIRET compte 14 chiffres (SIREN + NIC à 5 chiffres) et identifie l’établissement. Le dernier chiffre est une clé de contrôle calculée avec la formule de Luhn. Exception : pour les établissements de La Poste (SIREN 356000000), la somme des 14 chiffres doit être un multiple de 5, sauf le siège (35600000000048) qui suit la formule de Luhn. Cet outil vérifie uniquement le format et la clé : il ne peut pas confirmer que le numéro existe ni à qui il appartient.
Sources
Rule and exception: the French Wikipedia article on the SIRET system, which cites the INSEE Sirene users’ letter no. 16 (November 2013). Independently matched against the open-source python-stdnum fr/siret.py and fr/siren.py, whose doctest examples are used as test vectors. The INSEE PDF itself was not fetched; the register was not consulted.
What a passing checksum does and doesn’t tell you
This tool checks format and checksum only. A valid check digit proves the digits are internally consistent; it cannot confirm the number was ever issued, is active, or belongs to any company or person. There is no lookup against INSEE’s Sirene register. Runs entirely in your browser: nothing you type is transmitted, stored, or logged.