How a geo URI is written
A geo URI starts with geo: followed by latitude and longitude in decimal degrees, separated by a comma. The example geo:45.5231,-122.6765 points to downtown Portland, Oregon. The scheme is defined in RFC 5870, published in 2010.
Latitude comes first and ranges from -90 to 90; longitude comes second and ranges from -180 to 180. Coordinates use the WGS 84 system by default, the same one GPS uses.
- geo:45.5231,-122.6765 for latitude and longitude
- geo:45.5231,-122.6765,15 adds an altitude in meters
- geo:45.5231,-122.6765;u=30 adds an uncertainty radius in meters
- Negative latitude is south, negative longitude is west
Support and the maps-link alternative
Support for geo URIs varies by platform and app. Android generally hands geo: links to an installed maps app, while other systems and camera apps may show the text or ignore it.
For that reason many location QR codes use an ordinary web link to a map service instead, such as a Google Maps search URL with the coordinates or place name. A web link opens on almost any phone, falls back to a browser, and can point to a named business rather than a bare coordinate.