This data release was published in September 2023. It supersedes the previous postcode look-up dataset published in September 2022.
This release uses updated Office for National Statistics (ONS) Postcode Directory (ONSPD) and ONS Postcode Lookup (ONSPL) data from May 2023. The ONSPD and ONSPL lists all postcodes in the UK, and links them to higher geographies. Find out more about ONS postcode products.
Northern Ireland postcodes are subject to a separate licensing agreement. This release uses the January 2023 Northern Ireland Central Postcode Directory.
This note describes our annual update to our postcode look-up data, which consists of two parts:
- Postcode look-up data download. This data is available in CSV and Excel format and includes the area-based measure quintiles and other detailed information associated with UK postcodes. Extensive notes are provided as part of the data download. This data can be downloaded at the top of this page.
- Postcode look-up tool. This is a tool that allows users to search a single postcode to discover quintiles associated with the postcode and see where the postcode is found within the area used to assign the quintiles. It contains detailed descriptions of the different measures and what the tool was designed to do. By design the tool can search only one postcode at a time. The tool can be found on our ‘Search by postcode’ page. The information displayed in the postcode look-up tool is a subset of the postcode look-up data download.
Any questions or feedback related to these changes should be addressed to Elena Mollova at [email protected].
Summary of annual update
We have added 15,447 new postcodes to the look-up.
Each year we update our postcode look-up data to account for new postcodes and changes to existing postcodes by comparing the ONSPD and ONSPL from May of the current year with versions of the ONSPD and ONSPL from previous years.
Newly created postcodes are assigned quintiles using the following method. First, geographical areas are assigned a quintile as per our calculations when creating the measures. Second, all the postcodes within that area are assigned that quintile. As such, all the postcodes within an area will have the same quintile. The geographical area used varies depending on the measure in question. Our older measures (POLAR3, Adult HE 2001, Gaps) used CAS wards, while our newer measures (POLAR4, TUNDRA MSOA, Adult HE 2011) use Middle layer Super Output Areas (MSOAs). Our TUNDRA LSOA measure uses Lower layer Super Output areas (LSOAs).
For consistency, it is important that the quintile associated with a postcode does not change year-on-year. However, due to postcodes being reused and sometimes moving to different areas, it is possible for a postcode to be assigned to an area with a certain quintile one year but to a different area with a different quintile another year. Where a postcode has been reused and moved to an area with a different quintile, instead of being assigned this new quintile the postcode is assigned an ‘R’ to denote it has been reused and moved to an area with a different quintile. If a postcode has been reused and kept in the same area or reused and moved to an area that is assigned the same quintile as the original area, then the postcode will keep its quintile. This is because, despite this reuse, the quintile assigned to the postcode has been consistent and at no point in the past was the postcode assigned a different quintile. Our data download includes ‘Reason removed flags’ which detail if and why a postcode has had its area-based measure quintile set to ‘R’ instead of a number. This information is also displayed in our postcode look-up tool.
The assignment of postcodes to areas sometimes changes between versions of the ONSPD and ONSPL without the postcode being reused. When this happens, we report the area-based measure quintile based on the original area. This minimises the changes to our area-based measures when compared with earlier publications. We include various area fields in the data download to allow users to see the current area of the postcode (e.g. MSOA current) and the area when the quintile of the postcode was assigned (e.g. MSOA TUNDRA).
