Code-Point Open is a free, publicly available dataset published by Ordnance Survey, Great Britain's national mapping agency. It provides a single grid reference (a pair of coordinates) for the approximate centre of every postcode unit in the country. A postcode unit is the smallest geographic unit in the UK postcode system, typically covering a handful of addresses, such as a single street, a part of a street, or a single building. This dataset is a cornerstone for anyone working with UK location data, offering a lightweight, accessible way to map postcodes to a point on the ground.
What the dataset contains
Code-Point Open covers all postcode units in England, Scotland and Wales. It does not include Northern Ireland or Crown Dependencies. Each record in the dataset includes the full postcode (for example, SW1A 1AA), the corresponding Ordnance Survey grid reference (in easting and northing metres, based on the British National Grid), and a quality indicator that describes how the coordinate was derived. The coordinates are not the exact location of any building; they are a calculated central point for the postcode unit, often placed at the centroid of the addresses it contains. This makes the data suitable for broad mapping, analysis and visualisation, but not for precise property-level targeting.
How it fits into the UK postcode system
Postcodes in the UK are organised into a hierarchy: postcode area, postcode district, postcode sector, and finally postcode unit. Code-Point Open operates at the postcode unit level, which is the most granular tier. The dataset is a simplified version of the larger, more detailed Code-Point product, which Ordnance Survey sells commercially. The open version is released under the Open Government Licence, meaning it can be used freely for both personal and commercial projects without charge. It does not include address details, such as street names or house numbers, but it links to other datasets that do, such as the Royal Mail's Postcode Address File.
Why it matters for research
For someone researching an area, Code-Point Open is valuable because it provides a consistent, standardised way to locate postcodes on a map. You can use it to plot the distribution of services, such as GP surgeries or schools; to analyse demographic patterns by postcode; or to create geographic boundaries for analysis. Because it is free and widely used in open source mapping tools, it lowers the cost of entry for small businesses, community groups, and local researchers. However, it is important to remember that the coordinates are approximate. They should not be used for emergency response routing, for example, where the exact entrance of a building matters. The dataset is best suited for broad geographic work, such as calculating distances between postcodes, generating heat maps, or linking postcode data to census output areas.