Postnummer

Postnummer, or postal code, is a numeric or alphanumeric code used to identify a geographic area for the purpose of routing and delivering mail. It is assigned by the national postal service and is attached to a street address, together with the locality name. Postnummer improves automatic sorting, determines delivery routes, and supports service planning and statistical analysis.

Formats and coverage vary by country. In Denmark, the postnummer consists of four digits (for example, 1000). In Sweden, it is normally five digits, often shown with a space after the third digit (for example, 111 22). In other countries, the codes may be numeric or alphanumeric and can cover anything from a single large organization to a district within a city or a rural area. The boundaries and the assignment of postnummer can change over time as populations and infrastructure evolve.

Administration and use are coordinated by national postal authorities. Addresses typically include the postnummer between the street name and the locality. Postnummer data is widely used beyond mail delivery, including geocoding, logistics, marketing, insurance, emergency services, and regional planning. While a postnummer often correlates with recognizable geographic areas, it does not always align precisely with municipal or administrative borders.

History and significance: the system began in the 20th century to improve mail accuracy and speed and has since become a standard element of modern addressing. Today, postnummer remains a core component of addressing infrastructure in many countries and supports location-based services, navigation, and data analysis in addition to mail delivery.