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.
How ERP is built
The Census counts people where they usually live, but it never reaches everyone. To turn the count into an official population for 30 June of a Census year, the ABS:
- adds the net undercount measured by the Post Enumeration Survey, a follow-up survey run after each Census (0.7% in 2021, the lowest on record)
- adds Australian residents who were temporarily overseas on Census night
- moves the figure from Census night back to 30 June, allowing for births, deaths and migration in between.
Between Censuses, the ABS rolls the estimate forward with births, deaths and migration: quarterly for Australia and the states, and annually for SA2s, councils and other regions. After each new Census it rebases, revising the previous five years of estimates to line up with the new count.
ERP and the Census count
Because of these adjustments, ERP and the Census count for the same area won't match. They answer different questions. ERP is the better figure for how many people live somewhere and how fast that's changing. The Census is the only source for who those people are: their age, income, work, housing and households.
When the two are combined, for example a Census share applied to an ERP total, state which figure came from where. They describe different dates and are built in different ways.
Release timing
The ABS releases regional ERP once a year for the year to the previous 30 June. The release on 31 March 2026 covered 2024–25. After the 2026 Census, the ABS will publish rebased estimates for 30 June 2026, and small-area figures for the preceding years will be revised.
Census counts in Censible
Censible's figures come from the Census, so its population figures are Census counts by place of usual residence, not ERP. For the same area they will usually sit slightly below the ABS's official estimate. Census years before 2026 are shown on the 2026 boundaries as carried figures.
Sources: ABS, Methodology used in final rebased population estimates, June 2021; ABS, Regional population, 2024–25.
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.
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.
Carried figure
A count from an earlier Census moved onto newer boundaries with the ABS's population-weighted correspondences, so places can be compared across Censuses on the same map. Where a boundary didn't change, the carried figure is the ABS's own count; where it did, it's an estimate.
Census undercount and the Post Enumeration Survey
The Census undercount is the number of people the Census should have counted, less the number it did. The ABS measures it with the Post Enumeration Survey, run straight after each Census. In 2021 the net undercount was 0.7% of Australia's population, the lowest on record.
Population projection
An illustration of how a population would change if stated assumptions about births, deaths and migration held. The ABS says its projections are not predictions or forecasts, and they differ from estimates, which measure a population that already exists.
Place of usual residence and place of enumeration
Two ways the ABS counts people in the Census. Place of usual residence counts people where they usually live, generally the address where they have lived or intend to live for six months or more. Place of enumeration counts them where they were on Census night.
Questions people ask
Estimated resident population: the ABS's official measure of how many people live in Australia and in each region.
The Census count is the number of people counted on Census night by where they usually live. ERP adjusts that count for people the Census missed and residents who were overseas, dates it to 30 June, and updates it between Censuses.
Quarterly for Australia and the states and territories, and once a year for SA2s, councils and other regions.
After each Census, the ABS revises its population estimates for the previous five years so they line up with the new count. Small-area figures can move noticeably when this happens.