The ABS Index of Relative Socio-economic Advantage and Disadvantage (IRSAD) is the ABS’s summary measure of how advantaged an area is. At the 2021 Census, the middle suburb or locality scored 984. Where people live on the index differs by state: 20.5% of Northern Territory residents lived in the tenth of localities with the lowest scores nationally, followed by Tasmania (16.7%) and South Australia (12.3%), while 42.6% of ACT residents lived in the tenth with the highest scores, and 24.4% of New South Wales residents.
IRSAD scores are relative and ordinal: they rank areas, and a difference in scores is not an amount of advantage.
What IRSAD measures
IRSAD is one of four Socio-Economic Indexes for Areas (SEIFA) that the ABS builds from each Census. In the ABS’s words, it summarises information about the economic and social conditions of people and households within an area, and includes both relative advantage and disadvantage measures. It combines Census characteristics covering income, education, occupation, unemployment, housing, family composition and disability (the need for assistance with core activities): an area scores low if it has many households with low incomes or many people in low-skilled jobs and few with high incomes or skilled jobs, and high in the opposite case.
The ABS calculates scores for the smallest Census areas (Statistical Area Level 1) and standardises them so that the average is 1,000 and the standard deviation 100. A suburb’s score is the population-weighted average of the small areas within it. The ABS stresses that scores are an ordinal measure on an arbitrary scale: a higher score means relatively more advantage, but a score of 1,100 does not mean a place is 10% better off than one at 1,000. IRSAD is the input to Socio-Economic Advantage (24115), one of the five parts of APN Bedrock™ (Socio-Economic Position) (24110).
How localities are spread
| State or territory | Localities | Lowest tenth | Middle locality | Highest tenth |
|---|---|---|---|---|
| Australian Capital Territory | 100 | 1,040 | 1,091 | 1,155 |
| Victoria | 1,228 | 907 | 1,000 | 1,092 |
| New South Wales | 2,084 | 889 | 996 | 1,123 |
| Western Australia | 694 | 871 | 987 | 1,083 |
| South Australia | 691 | 867 | 977 | 1,085 |
| Queensland | 1,490 | 859 | 963 | 1,067 |
| Tasmania | 319 | 855 | 950 | 1,044 |
| Northern Territory | 162 | 647 | 943 | 1,068 |
| Australia | 6,772 | 875 | 984 | 1,094 |
APN calculation based on Australian Bureau of Statistics data: Socio-Economic Indexes for Areas (SEIFA), Australia, 2021, Suburbs and Localities, Indexes. IRSAD score at the 10th, 50th and 90th percentiles of localities in each state; localities with more than 200 residents.
Across the 6,772 localities with more than 200 residents, a tenth scored 875 or less and a tenth 1,094 or more. Between those tenths, scores sit evenly around the middle, about 110 points either side. The difference lies at the far ends of the range: 155 localities scored more than 200 points below the middle, against 24 more than 200 points above it, and the lowest score, 457, is more than twice as far from the middle as the highest, 1,217. The Northern Territory shows the low tail most clearly, with its lowest tenth of localities at 647 or below, far under any other state. In the ACT, even the lowest tenth scored 1,040 or more, above the national middle.
The least and most advantaged tenths
Residents in the tenth of localities with the lowest IRSAD scores nationally, 2021
APN calculation based on Australian Bureau of Statistics data: Socio-Economic Indexes for Areas (SEIFA), Australia, 2021, Suburbs and Localities, Indexes. Share of residents living in the tenth of localities with the lowest IRSAD scores nationally; localities with more than 200 residents.
Residents in the tenth of localities with the highest IRSAD scores nationally, 2021
APN calculation based on Australian Bureau of Statistics data: Socio-Economic Indexes for Areas (SEIFA), Australia, 2021, Suburbs and Localities, Indexes. Share of residents living in the tenth of localities with the highest IRSAD scores nationally; localities with more than 200 residents.
Nationally, the lowest-scoring tenth of localities held 7.4% of residents and the highest-scoring tenth 15.9%. The Northern Territory, Tasmania and South Australia had the largest shares in the lowest tenth; the ACT and New South Wales the largest in the highest tenth, and Tasmania the smallest (0.8%). IRSAD is one of the five measures combined in APN Bedrock™; how the states compare on all five together is set out in The Socio-Economic Ladder, State by State.
What this does not show
IRSAD describes areas, not people: a low-scoring suburb contains many advantaged households and a high-scoring one many disadvantaged ones. Scores rank areas against each other and cannot be added, averaged across states as quantities, or read as percentages. The tenths here are groups of localities ranked nationally; the ABS also publishes state rankings, which compare areas only within one state. The index describes 2021; SEIFA is recalculated from each Census. Localities of 200 residents or fewer are excluded.
- Australian Bureau of Statistics (Reference period: 2021) Socio-Economic Indexes for Areas (SEIFA), Australia [https://www.abs.gov.au/statistics/people/people-and-communities/socio-economic-indexes-areas-seifa-australia/2021], ABS Website, accessed 7 October 2026.
- Australian Bureau of Statistics (Reference period: 2021) Socio-Economic Indexes for Areas (SEIFA), Australia methodology [https://www.abs.gov.au/methodologies/socio-economic-indexes-areas-seifa-australia-methodology/2021], ABS Website, accessed 7 October 2026.
ABS material is used under a Creative Commons Attribution 4.0 International licence. Calculations, standardisations and index readings are APN’s and are not attributable to the ABS.
Findings are presented on the basis of data and evidence alone.
