What is the definition of a postcode district?
A UK postcode district is made up of a postcode area and one or two numbers that can define and split the area into smaller geographical areas. On average each area is split 21 districts, but this varies from area to area. A postcode district can be 2-4 digits in total. For example the ’B1’ postcode district covers a section of Birmingham whilst these four digits ‘SG13’ cover part of Hertford. In some instances, a postcode district can also include a letter such as the home of the TravelTime HQ 'EC1V'.
Postcode districts are also often referred to as the outward code or the outcode, this is all the information that is before the space in a full postcode. For example using Big Ben's postcode 'SW1A 0AA' the first four digits are the outward code and refer to a larger area and help the Royal Mail organise mail into bulk sorting locations. Once at the depot the inward code then narrows down the area to a few select addresses. In this example 'SW1A 0AA' refers to the Houses of Parliament only.
Postcode list providers
Here are a few sources where you can download a list of all districts:
Postcode districts map providers
Here are a few sources where you can download or purchase a map or check out our postcode mapping guide here.
The breakdown of a UK postcode
Create travel time polygons and matrices with the TravelTime API