Population FAQs

Q. How is population data used?
Q. I want to know the population of an area. Is the Census the best thing to use?
Q. What do you mean by “Estimated Resident Population (ERP)?”
Q. How is the Estimated Resident Population calculated?
Q. What is an actual location population estimate?
Q. What is a service population?


Q. How is population data used?

A. Population data is used for a number of purposes, including:

  • the distribution of Australian Government funds to state, territory and local governments
  • the apportionment of the number of seats in the House of Representatives
  • the formulation, monitoring and evaluation of government policy
  • market research
  • academic research
  • the denominator in per capita rates
  • informing on issues such as population ageing, fertility (the ability of a population to replace itself) and international migration.
More information about how population data is used can be found in Population Estimates: Concepts, Sources and Methods (cat. no. 3228.0.55.001).


Q. I want to know the population of an area. Is the Census the best thing to use?

A. The Census is ideal for information about the characteristics of the population in an area, e.g. level of education, income or family type, but should not be used for the number of people living in an area. Instead, estimated resident populations (ERP's) are the official estimates of the Australian population. The population of Australia and the states and territories is published in Australian Demographic Statistics (cat. no. 3101.0) every three months and the population of every local government area in Australia is published annually in Regional Population Growth, Australia (cat. no. 3218.0). Apart from being available more frequently than the five-yearly Census, the ERPs improve on the Census counts by place of usual residence by adjusting for the estimated net Census undercount and including Australian residents who were temporarily overseas at the time of the Census.

Back to top


Q. What do you mean by “Estimated Resident Population (ERP)?”

A.The Estimated Resident Population (ERP) is the official measure of Australia's population based on the concept of usual residence. It refers to all people, regardless of nationality or citizenship, 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. It excludes overseas visitors who are in Australia for less than 12 months. The ERP is based on the results of the Census of Population and Housing, adjusted for net undercount and Australian usual residents temporarily overseas on census night. The ERP is compiled as at 30 June of each census year and updated quarterly between censuses for Australia, states and territories and annually for smaller areas. Population measures based on place of usual residence are also referred to as the de jure population. More details about the concept of ERP, as adopted by the ABS for official population estimates, are contained in Information Paper: Population Concepts, 2008 (cat. no. 3107.0.55.006) and Population Estimates: Concepts, Sources and Methods (cat. no. 3228.0.55.001).


Q. How is the Estimated Resident Population calculated?

A.Two main steps are involved in estimating the national and state/territory population:
  • calculating the base population (Census year population estimates)
  • updating this base population (post-censal population estimates).
The post-censal population estimates are derived by bringing forward the base population by ageing the base, then adjusting for subsequent components of population growth, i.e. births, deaths, overseas and interstate migration. This method is called the cohort component method. The resulting population estimates then become the base population in the calculation of estimates for the following period. More details about the calculation of the ERP, as adopted by the ABS for official population estimates, can be found in Population Estimates: Concepts, Sources and Methods (cat. no. 3228.0.55.001).


Q. What is an actual location population estimate?

A. An 'actual location' population estimate is based on where people are actually located at a fixed point in time, for example, on Census night. This concept of place of enumeration is the simplest population concept because it does not require any consideration of where people usually live.

An actual location population estimate includes people on board vessels in or between Australian ports, or on long-distance buses or aircraft. The total of all persons counted on the place of enumeration basis is also referred to as the de facto population. More information about types of population estimates can be found in Information Paper: Population Concepts, 2008 (cat. no. 3107.0.55.006).

Back to top

Q. What is a service population?

A. A service population is a population that is counted in terms of persons who obtain particular goods and/or services in a particular location, over a specified time period. People in a service population may be permanent or temporary residents of the area from which the service is sought, or they may be daytime visitors (including commuters), overnight or short-term visitors to the area. Service populations could include:
  • commuter populations
  • daytrippers
  • tourists and other overnight visitors
  • temporary residents, such as:
    • seasonal workers (e.g. fruit pickers, other harvest and agricultural workers)
    • cyclical employees (e.g. fly-in/fly-out mine workers, members of parliament, senators and support staff in Canberra when Parliament is sitting)
    • winter-time visitors to sunbelt zones
    • residents of Aboriginal outstations in the dry season.
More details about different types of populations, including service populations, can be found in Population Estimates: Concepts, Sources and Methods (cat. no. 3228.0.55.001).