Scope
Australia's estimated resident population (ERP) includes all people who usually live in Australia (regardless of nationality, citizenship or visa status), with the exception of people present for foreign consular or diplomatic reasons.
Geographic coverage
This data covers Australia and its states and territories, as defined by the Australian Statistical Geography Standard, Edition 3.
ERP for Other Territories is available from September quarter 1993 onwards. Before then, Jervis Bay Territory was included in the ACT estimate, while Christmas Island and Cocos (Keeling) Islands were excluded from ERP. Norfolk Island has been included in Other Territories since 30 June 2016. Prior to this, the population of Norfolk Island was not part of Australia’s ERP.
The populations of Australian external territories are updated annually to fulfil the Commonwealth Electoral Act 1918, but are not part of Australia’s ERP. These external territories are:
- Territory of Ashmore and Cartier Islands
- Coral Sea Islands Territory
- Australian Antarctic Territory
- Territory of Heard and McDonald Islands
Sources
The latest ERP is based on adjusted 2021 Census counts, updated with quarterly estimates of births, deaths, overseas and interstate migration. Further information on each component can be found below.
Method
Quarterly ERP is calculated by taking the population estimate at the start of the quarter and adding natural increase (births minus deaths), net overseas migration and (in the case of state/territory populations) net interstate migration. These calculations are done for each age-cohort and sex. This is known as the cohort component method, and uses the demographic balancing equation.
The demographic balancing equation is:
\(P_{t+1} = P_{t} + B - D + NOM + NIM\) where:
\(P_{t}\) = the estimated resident population at time point \(t\)
\(P_{t+1}\) = the estimated resident population at time point \({t+1}\)
\(B\) = the number of births occurring between \(t\) and \({t+1}\)
\(D\) = the number of deaths occurring between \(t\) and \({t+1}\)
\(NOM\) = net overseas migration occurring between \(t\) and \({t+1}\)
\(NIM\) = net interstate migration occurring between \(t\) and \({t+1}\)
At the national level, net interstate migration is zero.
Revision status
The status of quarterly ERP data changes over time from preliminary to revised to final as new component data becomes available. Preliminary ERP is updated every quarter due to revisions to the component data for earlier quarters. ERP gets marked as revised once it can be expected not to change again until the final update, 22 months after the next Census.
The table below shows the current status of ERP and the components of population change. For explanation of the differences between preliminary, revised and final status, see explanatory notes for each component.
Quarters | Births and deaths | Overseas migration | Interstate migration | Estimated Resident Population |
---|---|---|---|---|
Sep.1991-Jun. 2021 | Final | Final | Final | FINAL |
Sep. 2021-Jun. 2022 | Revised | Final | Preliminary | REVISED |
Sep. 2022 | Preliminary | Final | Preliminary | PRELIMINARY |
Dec. 2022-Jun. 2023 | Preliminary | Revised | Preliminary | PRELIMINARY |
Sep. 2023 | Preliminary | Preliminary | Preliminary | PRELIMINARY |
Rebasing method
The 30 June ERP in a Census year is calculated by:
- adjusting Census counts of Australian usual residents to account for people missed or counted twice in the Census (based on Post Enumeration Survey results)
- demographically adjusting Census counts or net undercount estimates based on coherence with other data sources and to remove implausible demographic features
- adding usual residents temporarily overseas on Census night
- adjusting for births, deaths and migration from 30 June to Census night.
This new preliminary rebased ERP becomes the base for quarterly estimates going forward from that point until the next Census.
The difference between this new Census-based estimate (known as rebased ERP) and the quarterly component-based estimate (known as unrebased ERP) is called ‘intercensal difference’. Quarterly population estimates were revised between the current and previous Censuses by assuming intercensal difference accumulated evenly across the five-year period, except for Tasmania and the Australian Capital Territory.
Intercensal difference may result from error in the start population estimate, the end population estimate and/or in the quarterly estimates of births, deaths or migration. It is generally not possible to attribute intercensal difference to a particular source, or to quantify the error that each source contributes.
For further information see Methodology used in final rebased population estimates, June 2021.