Population density
The number of people living in an area divided by its land area, usually given as people per square kilometre. Australia as a whole has about 3.5 people per square kilometre.
How it's calculated
Population density divides an area's population by its land area. The ABS publishes it each year for SA2s, councils and larger areas in its Regional population release, using the estimated resident population (ERP) rather than the Census count.
Across Australia that gives about 3.5 people per square kilometre, a figure that says little about where people actually live. The densest inner-city SA2s in Melbourne and Sydney have more than 15,000 people per square kilometre, while the Northern Territory as a whole has fewer than one.
Why boundaries change the answer
Density depends as much on where a boundary is drawn as on how many people live inside it. An SA2 that includes a national park, an airport or farmland shows a low density even if its houses are closely packed, so two areas with the same density can look nothing alike on the ground.
The ABS also publishes a population grid, which counts residents in cells of one square kilometre across the country and avoids the boundary problem. On that grid, the federal Centre for Population found that 6.4% of Sydney's residents lived in cells with more than 10,000 people per square kilometre at June 2025.
Gross and residential density
Planners separate gross density, measured across the whole area, from net or residential density, measured only over land used for housing. Gross figures suit comparisons between regions. Residential density says more about the kind of housing in a neighbourhood.
Using density for location decisions
Density is an indirect measure of walkability, car dependence and how many potential customers live within a short trip. For a particular site, the number of people within a set distance, and who they are, answers the question more directly than a density figure for the surrounding area.
Population around a site in Censible
Censible counts the people inside a catchment around a point, either a circle of 1 to 10 kilometres or a drive or walk time, building the figure from the SA1s it covers. That gives the population a site can reach, with their age, income and household figures alongside, rather than a density for an area whose boundary may not suit the question.
Sources: ABS, Regional population, 2024–25; Centre for Population, Regional Population 2024–25 econote.
Estimated resident population (ERP)
The ABS's official measure of Australia's population. It starts from the Census count, adds people the Census missed and residents who were overseas, and is updated between Censuses with births, deaths and migration.
Statistical Area Level 2 (SA2)
A medium-sized area defined by the ABS to represent a community that interacts socially and economically. Most have between 3,000 and 25,000 residents.
Statistical Area Level 1 (SA1)
The smallest area the ABS uses to publish most Census data. An SA1 is a neighbourhood block of about 400 people, usually between 200 and 800, and SA1s fit together to form SA2s.
Catchment (trade area)
The area a store, clinic, school or other site draws its customers, patients or users from. A catchment can be drawn as a ring around the site, a drive or walk time, a hand-drawn boundary, or from where existing customers live.
Questions people ask
About 3.5 people per square kilometre. The figure varies enormously within the country, from more than 15,000 per square kilometre in inner Melbourne and Sydney to fewer than one across the Northern Territory.
An area's population divided by its land area in square kilometres. The ABS uses the estimated resident population for its published density figures.
Inner-city SA2s in Melbourne and Sydney, such as central Melbourne, Potts Point and Pyrmont, are consistently the densest in the country, each with more than 15,000 people per square kilometre.
They can use different population figures (the estimated resident population or a Census count), different boundaries, and different land areas, for example with or without parks and non-residential land.