Bruce September 18, 2025 GIS, Geography

Complete Guide to ONS Open Geography Portal Boundary Files Download

The Office for National Statistics (ONS) Open Geography Portal is the UK’s official platform for accessing free and open geospatial data. The portal serves as the UK’s official Office for National Statistics Open Data Geography Site, providing free and open access to the definitive source of geographic products, web applications, story maps, services and APIs under the Open Government Licence v3.0.

Main Portal URL: https://geoportal.statistics.gov.uk/

What Are Boundary Files?

ONS Geography produces digital boundary sets for a wide range of geographies. These boundary files are digital representations of geographic areas that can include administrative boundaries, census boundaries, electoral boundaries, and statistical boundaries across the UK.

Types of Boundaries Available

The portal provides access to various boundary types including:

Administrative Boundaries: Local Authority Districts, Counties, Regions
Census Boundaries: Output Areas, Lower Super Output Areas (LSOAs), Middle Super Output Areas (MSOAs), Wards
Electoral Boundaries: Parliamentary constituencies, Electoral divisions
Statistical Boundaries: Built-up areas, Travel to Work Areas
Health Geography: Clinical Commissioning Groups, NHS Trust boundaries

Accessing the Portal

Navigation Structure

The portal is organized through a ribbon menu system at the top of the page. Using the ribbon menu at the top of the page, navigate to: Boundaries > Census Boundaries > Lower Super Output Areas > 2021 Boundaries (as an example pathway).

Step-by-Step Navigation

Visit the Homepage: Access https://geoportal.statistics.gov.uk/
Use the Boundaries Tab: Click on “Boundaries” in the main navigation
Select Boundary Type: Choose from Administrative, Census, Electoral, or Statistical boundaries
Choose Specific Geography: Select your required geographic level (e.g., Wards, Local Authorities)
Select Temporal Coverage: Choose the relevant year/version of boundaries

Example Navigation Path

Under the Boundaries tab, navigate to Administrative Boundaries and then Wards / Electoral Divisions to access ward-level boundary files.

Available Download Formats

The portal offers multiple file formats to suit different applications and software requirements:

Primary Formats

Shapefile: The most common GIS format, a spatial data format that can include points, lines and polygons representing geographic boundaries
GeoJSON: Web-friendly format, the neatest way to process responses into a GeoDataFrame
KML: Google Earth compatible format
File Geodatabase: Esri’s native database format
Geopackage: Open standard geospatial data format

Download Options

You can download the datasets in different format as a Shapefile, GeoJSon, KML, File geodatabase, geopackage, etc by clicking the “download” button.

Download Process

Manual Download Method

Locate Your Dataset: Navigate to the specific boundary layer you need
Access Download Options: Click the “Download” button on the dataset page
Select Format: Choose your preferred file format from the available options
Download: The file will be downloaded to your device

Example: Downloading Local Authority Boundaries

Visit the Open Geography Portal and navigate to Boundaries > Administrative Boundaries > Local Authority Districts > 2018 Boundaries and choose Local Authority Districts (December 2018) Boundaries UK BGC from the list.

API Access

API Capabilities

You can also use the datasets as an API by clicking the API access options. This data is available for download or access via API from the Open Geography Portal.

API Documentation

For detailed API usage, refer to the official API documentation at:

API Catalogue: https://www.api.gov.uk/ons/open-geography-portal/
Portal Documentation: Available through the main portal interface

Programmatic Access

The API allows for programmatic access to boundary data, enabling automated downloads and integration into data processing workflows. This is particularly useful for researchers and analysts who need regular updates to boundary files.

Boundary Generalizations

The portal provides different levels of boundary generalization to balance file size with geographic accuracy:

Generalization Levels

Two versions of the England and Wales 2021 MSOA boundaries are: Generalised Clipped Boundaries: These boundaries are generalised to 20 meters. Super Generalised Clipped Boundaries: These boundaries are generalised to 200 meters.

Choosing the Right Generalization

Full Resolution: Use for detailed mapping and precise spatial analysis
Generalised (20m): Suitable for most mapping applications with reduced file sizes
Super Generalised (200m): Best for web mapping and overview visualizations

Licensing and Usage

All content is available under the Open Government Licence v3.0, except where otherwise stated. You can download all our products free of charge from the Open Geography portal.

License Terms

The Open Government Licence v3.0 allows you to:

Use the data for any purpose
Distribute and publish the data
Adapt and combine with other data
Use commercially and non-commercially

Recent Updates and Current Data

The portal regularly updates boundary files to reflect administrative changes. Local Authority Districts (December 2024) Boundaries UK BGC represents some of the most recent boundary updates available.

Staying Updated

Check the portal regularly for new versions
Subscribe to ONS geography updates through their main website
Use the API for automated access to the latest versions

Technical Considerations

File Formats for Different Applications

GIS Software (ArcGIS, QGIS): Use Shapefile or File Geodatabase
Web Applications: Use GeoJSON for best performance
Google Earth: Use KML format
R/Python Analysis: GeoJSON or Shapefile work well
Database Integration: Consider Geopackage format

Data Processing Tips

When working with boundary files:

Consider the appropriate generalization level for your use case
Check coordinate reference systems (typically British National Grid – EPSG:27700)
Validate geometry after download
Consider joining with statistical data using geography codes

Support and Documentation

Additional Resources

Main ONS Geography Page: https://www.ons.gov.uk/methodology/geography/geographicalproducts/opengeography
Digital Boundaries Information: https://www.ons.gov.uk/methodology/geography/geographicalproducts/digitalboundaries
Training Materials: https://onsgeo.github.io/geospatial-training/docs/practical_geog_and_stats

Getting Help

For technical support or data queries:

Check the portal’s built-in help documentation
Contact ONS Geography team through official channels
Consult the community resources and tutorials available online

The ONS Open Geography Portal provides comprehensive access to UK boundary files in multiple formats, making it an essential resource for researchers, analysts, and developers working with UK geographic data. The combination of manual download options and API access ensures that users can access data in the most appropriate way for their specific needs, whether for one-off projects or automated data processing workflows.