What is a postal code?
The postal code was introduced in Denmark in 1967 and consists of 4 digits. Numbers are assigned geographically — in general the number increases the further west and south you go: the 1000s cover Copenhagen, the 2000s cover the Copenhagen suburbs, 8000 is Aarhus, 9000 is Aalborg, and 6000–7000 cover Jutland.
Postal code vs. municipality
Postal codes and municipality boundaries are two different administrative divisions. A postal code can span several municipalities (e.g. 4400 Kalundborg covers both Kalundborg and Holbæk municipalities), and a municipality typically contains several postal codes. Use kommunekode on the individual address if you need an unambiguous municipality affiliation.
Bulk-recipient postal codes
Certain postal codes are bulk-recipient codes — reserved for large companies, public institutions or bulk mail recipients such as the tax authority, ATP or large banks. They typically have few or no geographic streets attached, and mail is sent directly to the recipient that owns the postal code. Examples: 0900 Copenhagen C (PostNord), 1790 Copenhagen V (Energinet).
How are postal codes updated?
The postal code system is administered by PostNord on behalf of the state. Changes to postal codes are rare (typically a few per year, often due to merging of districts). The geographic boundaries of postal codes are recorded in DAGI (Denmark's Administrative Geographic Divisions) and retrieved via the Datafordeler.
Look up postal codes via API
DanskAdresseAPI exposes postal codes at GET /v1/postnumre/[nr] (a single postal code) or GET /v1/postnumre?q=... (fuzzy search by name). Our per-postal-code SEO pages are at /postnr/[slug] — e.g. 8000 Aarhus C or 1050 Copenhagen K.