What is a Postcode Sector?

by Louisa Bainbridge
on Nov 9, 2017

What is the definition of a postcode sector?

A postcode sector combines a postcode area, a postcode district and a single character indicating the location's inward code. For example 'SW1A 0' is a sector which is made up of 'SW' which indicates South West London. This area has 139 sectors in it so the district, once focused into 'SW1A' there are only 3 sectors in this area and these are marked with an inward code to narrow this down even further to a more specific geographical area. These are marked numerically, with the district including three sectors numbered 0, 1 & 2. 

Whilst it varies across the UK, there are about 3000 addresses within each sector. There can be up to 10 different sectors within a postcode district and these are numbered 0-9.  The sector information is used by the Royal Mail to define the local area delivery office that the post should be distributed to. 

Postcode sector list providers

Here are a few sources where you can download a list of every postcode sector

Postcode sector map providers

Here are a few sources where you can download or purchase a map or check out our postcode mapping guide here.

















The break down of a UK postcode

All UK postcodes are made up of a range of different letters and numbers and follow this format: A postcode area, district, sector, unit.  

Learn more about postcodes at our postcode map and list resource centre


Learn more about postcode maps and tools



Creating a Population Radius Using TravelTime

Catchment area analysis: a distance-based radius doesn’t reflect accessibility to the location. TravelTime allows search based on time instead of distance.

Chris Hutchinson Feb 17, 2020

Use this Postcode Map Guide to View Postcode Data on a Map

Use the postcode map guide to discover how postcodes are created. View relevant postcode data on a map. Compare a postcode map to a travel time map.

Evelina Bezubec Aug 5, 2019

The Ultimate Postcode Database Guide

This postcode database guide helps you find the right postcode database for your use case. Make a postcode list for data analysis, advertising and e-commerce.

Niharika Sisodia Aug 30, 2018

4 Easy Ways to Make a UK Postcode List

Explore ways to create a UK postcode list and download the data. Explore free postcode lists, the most updated lists, lists good for e-commerce & more.

Louisa Bainbridge Feb 7, 2018

What is a Postcode District?

The definition of a postcode district is explained with examples. Find out how are they defined and find out who can supply postcode district maps and lists.

Louisa Bainbridge Nov 10, 2017

What are Postcode Areas?

This article explores the background of postcode areas and what they mean. Find out how are they defined and get a list of mapping and list providers.

Louisa Bainbridge Nov 9, 2017