Statistical geographies
Statistical geographies are areas used to collect and report data in a consistent way. They are designed to stay as stable as possible over time. This makes it easier to compare data from one period to another.
One of the main benefits of these areas is that they do not change as often as administrative boundaries such as electoral wards. Boundary changes can make it difficult to track trends so statistical areas avoid this problem.
Sometimes, these boundaries do change—but only when there has been a big change in the number of people or households, as recorded in the Census. When this happens, an area may be split if its population has grown too much or an area may be merged with a neighbour if its population has become too small.
Output areas and super output areas always fit inside local authority boundaries.
You can explore these areas using our interactive map.
For more detailed information about statistical geographies in England, please visit the Statistical geographies page on the Office for National Statistics (ONS) website.
Output areas (OA)
Output areas are the smallest areas used for Census statistics. They are the basic building blocks used to create larger statistical areas and help ensure data is reported in a consistent way.
- First introduced for the 2001 Census
- Updated after the 2011 and 2021 censuses because of population and household changes
- They usually contain 40 to 250 households
- They typically have 100 to 625 residents
During Census 2021, output areas stayed the same if they still met the population and household thresholds. If not, they were split or merged so that all areas continued to meet the required size.
Super output areas
Super output areas are larger than output areas and used widely for reporting statistics. They come in two levels:
Lower Layer Super Output Areas (LSOAs)
- Usually made up of groups of 4 or 5 output areas
- Include 400 to 1,200 households
- Have 1,000 to 3,000 residents
Middle layer Super Output Areas (MSOAs)
- Usually made up of 4 or 5 LSOAs
- Include 2,000 to 6,000 households
- Have 5,000 to 15,000 residents
- Always fit within a single local authority
