Postcode to Latitude & Longitude

This tool converts any UK postcode into its geographic coordinates — latitude and longitude in both decimal degrees and degrees-minutes-seconds (DMS) format — along with the Ordnance Survey National Grid reference. Whether you're building a location-based application, plotting data on a map, or working with GIS software, this gives you the exact coordinates you need.

Understanding the Output

Each postcode lookup returns several coordinate formats. Decimal degrees (e.g. 51.501009, -0.141588) are the most widely used in web mapping APIs, databases and programming. DMS notation (e.g. 51° 30' 3.63" N, 0° 8' 29.72" W) is the traditional geographic format you'll find on printed maps and in navigation. The OS Grid Reference (e.g. TQ 29 79) is the standard Ordnance Survey notation used across Great Britain.

Coordinate Accuracy

The coordinates represent the centroid of the postcode unit, not an individual property. A typical UK postcode covers around 15 properties, so the coordinates will be accurate to within approximately 50-100 metres of any specific address within that postcode. For most mapping, delivery routing and analysis purposes this level of accuracy is more than sufficient.

Six decimal places of latitude and longitude give precision to approximately 0.11 metres, which is far more precise than the postcode centroid itself. If you need building-level accuracy, you'll need a full address geocoding service rather than postcode-level lookup.

What is Latitude and Longitude?

Latitude measures how far north or south a location is from the equator, ranging from -90° (South Pole) to +90° (North Pole). The UK sits between approximately 49.9°N (Channel Islands) and 60.9°N (Shetland). Longitude measures how far east or west a location is from the Prime Meridian at Greenwich, London. The UK spans from approximately 1.8°E (Lowestoft) to 8.2°W (western Scotland).

Together, latitude and longitude form a precise coordinate pair that uniquely identifies any point on Earth. These coordinates use the WGS84 datum, the global standard used by GPS systems, Google Maps, and most web mapping platforms.

Ordnance Survey Grid References

The OS National Grid is a coordinate system specific to Great Britain (not Northern Ireland) that divides the country into 100km squares, each identified by a two-letter code. Within each square, easting (west-to-east) and northing (south-to-north) values specify the location in metres.

A 6-figure grid reference like SD 712 064 identifies a 100-metre square. The first three digits (712) are the easting, and the last three (064) are the northing within the SD square. This system is widely used on Ordnance Survey maps, by walkers, in planning applications, and by emergency services.

The OS grid uses the Airy 1830 ellipsoid and OSGB36 datum, which differs slightly from the WGS84 datum used by GPS. This tool performs the Helmert transformation to convert between the two systems accurately.

Common Uses

Web Development & APIs

Developers frequently need to convert postcodes to coordinates for mapping features, store locators, delivery radius calculations, and geofencing. Most mapping APIs like Google Maps, Mapbox and Leaflet work with decimal degree coordinates, making this conversion essential for any postcode-based mapping feature.

Data Analysis & GIS

Data analysts and GIS professionals use postcode coordinates to geocode datasets, create choropleth maps, perform spatial analysis, and calculate distances between locations. Converting postcodes to coordinates is often the first step in any geographic data analysis pipeline.

Logistics & Delivery

Route planning, delivery zone mapping, and distance calculations all require coordinate data. Converting customer postcodes to lat/lng allows logistics companies to optimise routes, calculate ETAs, and define delivery areas programmatically.

Research & Planning

Urban planners, researchers and surveyors use coordinate data to map census boundaries, plot survey points, and analyse spatial relationships. The OS grid reference output is particularly useful for UK-based planning and surveying work where OS maps are the standard.

Bulk Postcode Conversion

This tool is designed for individual postcode lookups. If you need to convert a large batch of postcodes to coordinates, consider using the Postcodes.io API or the Ordnance Survey Data Hub API, both of which support bulk geocoding requests. For datasets already containing postcodes, tools like QGIS can perform batch geocoding using the Code-Point Open dataset from Ordnance Survey.

Datum and Projection Notes

The latitude and longitude values returned by this tool use the WGS84 datum (EPSG:4326), which is the global standard for GPS and web mapping. The OS grid reference uses the OSGB36 datum (EPSG:27700) with the Airy 1830 ellipsoid. There is a small difference between these datums,typically 5-10 metres in Great Britain, which this tool accounts for using a 7-parameter Helmert transformation. If you're working in GIS software, ensure you specify the correct coordinate reference system for your use case.