Location technology
What Is Geocoding? Turning Addresses Into Coordinates
Geocoding converts a written address or place name into latitude and longitude. Learn how it works, why results vary and where it falls short.
Updated 14 October 2026 · 3 min read
Geocoding is the process of converting a human-readable description of a place, usually an address, into geographic coordinates. You give it text such as a street, number and city, and it returns a latitude and longitude that software can put on a map, measure with or store.
How a geocoder works
Most geocoders follow three steps:
- Parse: split the text into parts such as number, street, locality, postcode and country. Different countries order and name these differently, as shown in the addresses worldwide hub.
- Match: compare the parts against a reference dataset of streets, buildings, postcodes and places, and choose the best candidate.
- Locate: return coordinates for that candidate.
Where the coordinates come from
The point returned depends on what the reference data holds:
- Building or address point: the best case, a point at or near the actual structure.
- Street interpolation: the geocoder knows where a street starts and ends and the number range, and places the number proportionally along it. This can be off by tens of metres, and may fall on the wrong side of the road.
- Postcode or area centroid: when only a postcode, town or region is matched, the result is a central point of that area. This may be a long way from the actual address.
Good geocoders report how confident they are and what kind of match they made. If this information is available, use it.
Why results vary
- Address data is incomplete or out of date in many places, especially in fast-growing areas.
- Spelling and local naming variations confuse matching.
- In some places houses are not numbered, so there is nothing precise to match.
- Different providers use different reference data and give different answers for the same text.
Geocoding is an approximation
Because of these limitations, a geocoded point is an estimate of where an address probably is. It is not the same as a surveyed entrance. Where the exact spot matters, such as the gate of a large compound, the best approach is to select the point on a map directly and record it as a location code or as coordinates. See how to find the coordinates of a place.
The opposite direction
Going from coordinates back to a description is a different process, covered in what reverse geocoding is.
UPCS does not offer address search or validation as a product. It works from a point you choose on the map and produces a code for it.
Frequently asked questions
What is the difference between geocoding and reverse geocoding?
Geocoding turns an address or place name into coordinates. Reverse geocoding does the opposite and turns coordinates into an address or place name.
Why does a geocoder sometimes return a point on the wrong side of the street?
Many geocoders estimate a position by interpolating along a street segment based on the house number, which can be off by tens of metres.