Geocoding

How geocoding works

A geocoder matches an address against a reference list of known addresses and returns the coordinates of the match. The ABS defines geocoding as assigning a geocode to a piece of information using known location details such as a coordinate, address or suburb, and its guidance recommends that geocoded records carry both a coordinate and an ASGS mesh block code. Once a record has a point, a point-in-polygon step assigns it to any boundary, and the ABS rates geocoding and point-in-polygon allocation as the most accurate ways to move data onto its areas, ahead of correspondences, which it rates least accurate.

Reverse geocoding converts a point to its nearest address or place, which is how a location picked on a map is given a street address.

Match levels

The ABS advises that geocoding results record how closely each address matched the index, because a coordinate is very accurate when the address is tied to a land parcel and much less accurate when it rests on a street midpoint or a locality, which can place a record in the wrong area. In G-NAF, Geoscape's August 2026 release report grouped principal addresses by the level they were geocoded to.

• Address level (98.11%): the point sits within, or near, the property's boundary.
• Street level (1.83%): the point is at the centre of the street within its locality.
• Locality level (0.06%): the point is at the centre of the suburb or locality.

Geoscape notes that where an SA2 boundary splits a locality, an unknown share of addresses placed at the locality centre will be coded to the wrong SA2, and the ABS recommends using addresses geocoded only to street or locality level for SA2s and larger areas.

Mistakes geocoding prevents

• Assigning by postcode. Postcodes cut across suburbs and councils, and the ABS states that postcodes are not recommended as a source of geocoding information. A point geocoded at address level places each record in the suburb, SA2 or council it is actually in.
• Using postal addresses. The ABS notes that a postal address can be far from the physical one, such as a rural property whose post office box is in a town many kilometres away, and it prefers the physical address for locating people. G-NAF is built to hold physical addresses.
• Losing shop and unit detail. G-NAF records the unit, shop or level part of an address as a secondary address with a flat type such as SHOP or UNIT, which can be linked to the building's primary address. Checking the match level of addresses in shopping centres and apartment buildings shows whether they reached the site or only the street.
• Treating rural addresses like urban ones. The ABS notes that rural and remote addresses are harder to geocode than urban ones, and that some still use lot and section numbers.

Geocoding in Australia

The ABS describes G-NAF, produced by Geoscape Australia, as the national authoritative list of physical addresses and recommends it for geocoding. In 2012 the ABS noted that it didn't offer an address geocoding service of its own, and it arranged for mesh block codes to be included in G-NAF so that addresses can be related to ABS boundaries. G-NAF is updated quarterly and is available free under an open licence.

Geocoding and Censible

Censible geocodes the addresses in a Sites upload. It uses a row's own latitude and longitude when they fall in Australia, then matches the street address against G-NAF, removing shop, unit and level prefixes and requiring the street to be in the suburb or postcode the address names. An address it can't match is placed at the middle of its suburb, then its postcode, and marked to check, and anything left over is placed by hand on the map.

Sources: ABS, Statistical Spatial Framework guidance: Geocoding unit record data using address and location; ABS, ASGS Edition 4, Using the ASGS; Geoscape Australia, G-NAF Data Release Report, August 2026.