SA1 coding structure:

SA1s are identified by an 11-digit fully hierarchical code. The SA1 identifier is a 2-digit code, assigned within a Statistical area level 2 (SA2).

There are 57,523 SA1s. In aggregate, they cover the whole of Australia without gaps or overlaps. These include 33 non-spatial SA1 special purpose codes, comprising Migratory–Offshore–Shipping and No Usual Address codes for each State and Territory.

SA1s are designed to be either a predominantly rural or predominantly urban in character, with SA1s in rural and remote areas generally having a lower population than in urban areas. SA1s are designed to be internally connected by road, except for groups of unpopulated islands and Aboriginal and Torres Strait Islander communities, which may not be contiguous. Areas without permanent population (such as lakes, commercial areas, national parks etc.) are often represented by 'zero SA1s' - these are SA1s with an effective design population of zero.

SA1s are also used as the building blocks for a number of Australian Statistical Geography Standard (ASGS) defined regions including the Indigenous Structure, the Section of State and Urban Centre and Localities Structures, and the Remoteness Structure. Within the Non-ABS Structure, SA1s are used to approximate a number of administrative regions, such as Commonwealth Electoral Divisions and State Electoral Divisions.