Postal Code 78420 – Carrières-sur-Seine, Yvelines

Postal Code 78420 for Carrières-sur-Seine, Yvelines is part of the France postal code system, which uses a numeric code of 5 digits (e.g. 75001). Addresses here are organised as Region → Department → Arrondissement → Commune → Locality.

Administratively it is recorded in Yvelines within France. Postal codes are assigned by delivery route rather than by administrative boundary, so a single code can cover more than one locality and a locality can fall under several codes.

No building-level records are held for this code in the imported dataset, so only the code and its location details are shown. The absence of records does not mean the postal code is unused.

Couriers, e-commerce checkout forms and address autocomplete tools all rely on the postal code to route mail and to check that a stated address matches the code. Because a postal code identifies a delivery area rather than a single building, two addresses that share the same code can still be some distance apart.

Always write France Postal Code in full when completing a form, including any leading zero. Enter a 5-digit French postal code. Data source: a third-party open dataset. This is a reference snapshot, not a live government feed, so confirm the code with the sender, carrier or postal authority before relying on it.