Australia's Population by Country of Birth methodology

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Reference period


1. Australia's population estimates by country of birth are compiled annually as at 30 June. These estimates, produced by single year of age and sex, classify the population according to country of birth.

2. Country of birth estimates at the state and territory level are only available for Census years. 


ABSAustralian Bureau of Statistics
ACTAustralian Capital Territory
A TAntarctic Territory
ASGSAustralian Statistical Geography Standard
cat. no.catalogue number
COVID-19coronavirus disease 2019
Dem RepDemocratic Republic
DpDutch part
EEast or Eastern
ERPestimated resident population
E TExternal Territories
FrFrance or French part
F SFederated States of
Gaza Str/W BankGaza Strip and West Bank
Home AffairsAustralian Government Department of Home Affairs
NNorth or Northern
necnot elsewhere classified
nfdnot further defined
NIMnet interstate migration
NOMnet overseas migration
NSWNew South Wales
NTNorthern Territory
PNGPapua New Guinea
SSouth or Southern
SASouth Australia
SACCStandard Australian Classification of Countries
SARSpecial Administrative Region
SESint Eustatius
UKUnited Kingdom
UK, CIs & IOMUnited Kingdom, Channel Islands and Isle of Man
USUnited States
USAUnited States of America
WWest or Western
WAWestern Australia
WHOWorld Health Organisation



1. The classification of countries used in this release is the ABS' Standard Australian Classification of Countries, 2016. The entire historical series has been backcast using this version of the classification.

State and territory

2. Estimated resident population (ERP) data covers Australia and its states and territories, as defined by the Australian Statistical Geography Standard (ASGS) 2016.  For historical changes see the Scope section in the left hand navigation bar.


1. The ABS collects statistical information under the authority of the Census and Statistics Act 1905. This requires that statistical output shall not be published or disseminated in a manner that is likely to enable the identification of a particular person or organisation.

2. Some techniques used to guard against identification or disclosure of confidential information in statistical tables are suppression of sensitive cells, random adjustments to cells with very small values and rounding. In these cases, data may not sum to totals due to the confidentialisation of individual cells.

3. The statistics in this release have been rounded to the nearest 10 to maintain confidentiality. Where figures have been rounded, discrepancies may occur between sums of component items and totals. All calculations and analysis are based on un-rounded data. Calculations made on rounded data may differ to those published.

Data sources

1. The latest estimated resident population (ERP) is based on adjusted 2016 Census counts, updated with quarterly estimates of births, deaths, overseas and interstate migration. Further information on each component can be found in the National, state and territory population methodology page.

2. Statistics in this release draw extensively on information provided by individuals in the Census, Home Affairs, Medicare, the Department of Defence, and birth and death registrations in each state and territory. Their continued cooperation is very much appreciated: without it, the wide range of statistics published in the ABS on Australia's population would not be available. Information received by the ABS is treated in strict confidence as required by the Census and Statistics Act 1905.


Australian resident

For estimated resident population statistics, the Census year population estimates classify a person as an Australian resident if the person resides in Australia for 12 months or more. See also Estimated Resident Population (ERP) in this Glossary.

Australian Statistical Geography Standard (ASGS)

The ASGS brings all the regions for which the ABS publishes statistics within the one framework and has been in use for the collection and dissemination of geographically classified statistics since 1 July 2011. It is the current framework for understanding and interpreting the geographical context of statistics published by the ABS.


A census is the complete enumeration of a specific population at a point in time (as opposed to a survey, which enumerates a sample of the population). When the word is capitalised, "Census" refers to the national Census of Population and Housing. The Census is run by the ABS every five years and aims to count every person in Australia on Census night.

Census count

The Census of Population and Housing enumerates persons on the basis of where they were located on Census Night. The Census also compiles information on people according to their place of usual residence. This means that Census counts of people can be produced according to their location on Census Night as well as their place of usual residence. Characteristics of households are based on persons usually resident in a dwelling.

Country of birth

Country of Birth is defined as the country in which a person was born.


The process of leaving one country to take up permanent or semi-permanent residence in another. 

Estimated resident population (ERP)

The official measure of the population of Australia is based on the concept of usual residence. It refers to all people, regardless of nationality, citizenship or legal status, who usually live in Australia, with the exception of foreign diplomatic personnel and their families. It includes usual residents who are overseas for less than 12 months over a 16 month period. It excludes overseas visitors who are in Australia for less than 12 months over a 16 month period.


The process of entering one country from another to take up permanent or semi-permanent residence. 

Median age

The age at which half the population is older and half is younger.

Migrant - international

An international migrant is defined as "any person who changes his or her country of usual residence" (United Nations 1998). The country of usual residence is the country in which a person lives, that is to say, the country in which they have a place to live where they normally spend the daily period of rest. A long-term international migrant is a person who moves to a country other than that of their usual residence for a period of at least a year (12 months), so that the country of destination effectively becomes their new country of usual residence.

In Australia, for the purposes of estimating overseas migration, and thereby the official population counts, a person is regarded as a usual resident if they have been (or expected to be) residing in Australia for a period of 12 months or more over a 16 month period.


The movement of people across a specified boundary for the purpose of establishing a new or semi-permanent residence. Migration can be international (migration between countries) and internal (migration within a country).

Net overseas migration (NOM)

Net overseas migration is the net gain or loss of population through immigration to Australia and emigration from Australia. Under the current method for estimating final net overseas migration this term is based on a traveller's actual duration of stay or absence using the '12/16 month rule'. Preliminary NOM estimates are modelled on patterns of traveller behaviours observed in final NOM estimates for the same period one year earlier.

NOM is calculated as follows:

NOM = overseas migrant arrivals - overseas migrant departures

Other territories

Other territories include Christmas Island, Cocos (Keeling) Islands, Jervis Bay Territory and Norfolk Island. For more information see the Classifications section in this methodology page.

Overseas migrant arrivals

Incoming international travellers who stay in Australia for 12 months or more over a 16-month period, who are not currently counted within the population, and are then added to the population. Overseas migrant arrivals are also referred to as immigrants.

Overseas migrant departures

Outgoing international travellers who leave Australia for 12 months or more over a 16-month period, who are currently counted within the population, and are then subtracted from the population. Overseas migrant departures are also referred to as emigrants.

Overseas migration

See net overseas migration (NOM).

Place of usual residence

See usual residence.

Rebasing of population estimates

After each Census, the ABS uses Census counts (adjusted for undercount) to construct a new base population figure for 30 June of the Census year. Rebasing is the process of updating population estimates for the five years between Censuses, to incorporate information from the most recent Census.

Sex ratio

Sex ratio is the number of males per 100 females. 

State or territory of usual residence

State or territory of usual residence refers to the state or territory of usual residence of:

  • the population (estimated resident population);
  • the mother (birth collection); and
  • the deceased (death collection).

In the case of overseas movements, state or territory of usual residence refers to the state or territory regarded by the traveller as the one in which they live or have lived. State or territory of intended residence is derived from the intended address given by migrants, and by Australian residents returning after a journey abroad. Particularly in the case of the former, this information does not necessarily relate to the state or territory in which the traveller will eventually establish a permanent residence.

Usual residence

Within Australia, usual residence is the address of the dwelling at which a person considers themselves to currently live, either having lived there for some time or intending to live there for some time.

The usual residence of a newborn is that of the mother.


1. The estimated resident population (ERP) is calculated each quarter 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 each quarter and for country of birth annually at the national level. This is known as the cohort component method, and uses the demographic balancing equation.

2. 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.

3. The country of birth estimates for post-censal years are compiled using the Census year data by country of birth as a base. They are then updated annually for each of the components of population change by country of birth: adding births (all Australian), subtracting deaths, and adding the net of overseas migration (overseas migrant arrivals minus overseas migrant departures). 

Revision status

1. The status of the quarterly estimated resident population (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.

2. The table below shows the current status of ERP and the components of population change: natural increase, overseas migration and interstate migration. Further information on each component can be found in the National, state and territory population methodology page.

QuartersBirths and deathsOverseas migration Interstate migration Estimated Resident Population
Sep.1991-Jun. 2016 Final Final Final FINAL 
Sep. 2016-Jun. 2020RevisedFinalPreliminaryREVISED 
Sep. 2020Preliminary FinalPreliminaryPRELIMINARY - updated due to revised component data 
Dec. 2020 - Jun. 2021Preliminary RevisedPreliminaryPRELIMINARY - updated due to revised component data 
Sep. 2021Preliminary PreliminaryPreliminaryPRELIMINARY



1. 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 military, consular or diplomatic reasons.

2. Australia’s population estimates for the period since 1971 are compiled according to the place of usual residence of the population. An explanation of the place of usual residence conceptual basis for population estimates is given in Information Paper: Population Concepts (cat. no. 3107.0.55.006). 

Geographic coverage

3. Estimated resident population (ERP) data covers Australia and its states and territories, as defined by the Australian Statistical Geography Standard (ASGS) 2016.

4. Jervis Bay Territory, the Territories of Christmas Island, Cocos (Keeling) Islands and Norfolk Island are included as one spatial unit at the State and Territory level under the category of Other Territories.

Historical changes

5. 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.

6. 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.

Statistics and variables available

1. The ABS may have other relevant data available on request. Generally, a charge is made for providing this information. Inquiries should be made to the ABS website Contact Us page.

2. The following variables for the estimated resident population (ERP) by country of birth data may be made available on request:

  • Age - by single year or grouped
  • Country of birth
  • Region of birth
  • Reference year (as at 30 June)
  • Sex
  • State or Territory of residence (only available for Census years)
  • Status of ERP (preliminary, revised or final).
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