Household and Family Projections, Australia methodology

Across the community, a wide variety of living arrangements exist with complex family structures. The quality of family and household data in the Census is partly dependent on people’s ability to describe these relationships within the constraints of the generalised questionnaire format required by a Census. 

Some household living arrangements can be fluid, and the Census assigns each person to a single discrete household. The projection method therefore treats households as discrete units.

Figures of less than one million have been rounded in the text to the nearest hundred while figures of more than one million are rounded to the nearest hundred thousand.

Changes in population over time are commonly discussed in terms of average annual growth rates. In this publication, however, changes are for the most part presented as percentage increases or decreases over the entire 25-year period (from 2021 to 2046), in order to make differences between projected numbers (of households, families and people in different living arrangements) more discernible.

Some state and territory governments produce household projections, which may be a useful complement to the projections in this publication. These are typically based on different methods and are produced with specific attention to the observed and expected trends of that state, without the requirement of being constrained to Australia level data.

The Australian Bureau of Statistics (ABS) household and family projections are produced using a combination of ABS data which includes the 5-yearly Census of Population and Housing, the estimated resident population, and population projections. 

For information on the institutional environment of the ABS, including the legislative obligations of the ABS, financing and governance arrangements, and mechanisms for scrutiny of ABS operations, please see ABS Institutional Environment.

Household and family projections inform future changes in numbers and types of households and families, and are used in a variety of planning decisions. Projections are published for Australia, the states, territories, capital cities and rest of state regions.

ABS household and family projections are compiled and published once every five years; typically, three years following the most recent ABS Census of Population and Housing. 

ABS household and family projections are based on assumptions about future living arrangements of Australia's population. They are not intended as predictions or forecasts, but are illustrations of growth and change in numbers and types of households and families that would occur if assumptions about future living arrangements of Australia's population were to prevail over the projection period. 

While the assumptions are formulated on the basis of an assessment of demographic trends, there is no certainty that any of the assumptions will be realised. In addition, no assessment has been made of possible future changes in non-demographic conditions.

It is important to also recognise that the future population of Australia underlying the household and family projections is itself based on a range of assumptions (about future fertility rates, mortality rates and levels of migration). For the purpose of this publication, the medium series projection from Population Projections, Australia, 2022 (base) - 2071 has been used as Australia's future population. 

As the assumptions used in each successive set of household and family projections incorporate recent trends, comparison of data across issues of this publication is not possible.

Estimates of the number of families in 2021 in this publication differ from counts of families from the 2021 Census of Population and Housing. This is due to estimates of families in this publication being based on 2021 estimated resident population as well as 2021 Census living arrangement propensities. The 2021 estimated resident population of Australia is greater than the 2021 Census count of people in Australia as it includes Census net undercount and residents temporarily overseas, and as a result, the number of families based on 2021 estimated resident population is greater than the number of families from the 2021 Census.

ABS household and family projections are not intended as predictions or forecasts, and should not be considered as such. Rather, they are illustrations of growth and change in numbers of households and families in Australia that would occur if the assumptions were to prevail over the projection period. As future trends in living arrangements are unpredictable, three assumptions have been made regarding these, to illustrate a range of possible future outcomes.

This publication contains notes on the assumptions and methods used to produce the household and family projections. It also contains Explanatory Notes, Appendices and a Glossary that provide information on the data sources, terminology, classifications and other technical aspects associated with these statistics.

ABS household and family projections are available in a variety of formats on the ABS website:

• Summary publication, which contains key figures and commentary;
• One data cube (in Excel format) containing living arrangement propensities for Australia for the 2006 to 2021 Censuses; and
• ABS Data Explorer datasets containing households, families, and persons by living arrangement for Australia, the states, territories, capital cities and rest of state regions, for 2021 to 2046 for all projection series.

If the information you require is not available as a standard product, then ABS Consultancy Services can help you with customised services to suit your needs. For inquiries contact the National Information and Referral Service on 1300 135 070. Alternatively, email client.services@abs.gov.au.

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. For further information refer to Australian Statistical Geography Standard (ASGS) Edition 3.

Average household size refers to the number of persons per household in private dwellings.

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.

A child is a person of any age who is a natural, adopted, step or foster son or daughter of a couple or lone parent, usually resident in the same household. A child is also any individual under 15 years, usually resident in the household, who forms a parent-child relationship with another member of the household. This includes otherwise related children under 15 years and unrelated children under 15 years.

In order to be classified as a child, the persons can have no partner or child of his/her own usually resident in the household. A separate family in the household is formed in this instance. If a person is aged under 15 years and has a partner/spouse these relationships are not recorded.

A family based on two persons who are in a registered or de facto marriage, who are usually resident in the same household. The family must include one or more children usually resident in the same household. The family may include any number of other related individuals usually resident in the household.

A family based on two persons who are in a registered or de facto marriage, who are usually resident in the same household and have no children usually resident in the same household. The family may include any number of other related individuals usually resident in the household.

A dwelling is a building or structure in which people live. Some examples of dwellings are a house, a block of flats, a caravan or tent, prison, humpy or houseboat. For the purposes of Census of Population and Housing, dwellings are classified into private and non-private dwellings. Each of these dwelling types is further divided into occupied and unoccupied dwelling categories.

Estimated households is a measure of the number of households, which corresponds to the usual resident population living in private dwellings. It is based on the Census count of households and adjusted to account for dwelling undercount, dwelling misclassification, residents counted away from home on Census night and residents temporarily overseas on Census night. It excludes groups of visitors (from overseas or elsewhere in Australia) counted by Census in the same dwelling, as they do not form a household. 

Two or more persons, one of whom is at least 15 years of age, who are related by blood, marriage (registered or de facto), adoption, step or fostering, and who are usually resident in the same household. The basis of a family is formed by identifying the presence of either a couple relationship, lone parent-child relationship or other blood relationship. Some households will contain more than one family.

A classification of families based on the presence, or absence, of a couple relationship, parent-child relationship, or other blood relationship.

Growth in the number of families.

Represent the socioeconomic area of each of the eight state and territory capital cities. GCCSA boundaries represent a broad socioeconomic definition of each capital city, they contain not only the urban area of the capital city, but also surrounding and non-urban areas where much of the population has strong links to the capital city, through for example, commuting to work. For further information refer to Australian Statistical Geography Standard (ASGS) Edition 3.

A group household is a household consisting of two or more unrelated people where all persons are aged 15 years and over. There are no reported couple relationships, parent-child relationships or other blood relationships in these households.

A household is defined as one or more persons, at least one of whom is at least 15 years of age, usually resident in the same private dwelling. 

Persons usually resident in non-private dwellings, such as hotels, motels, boarding houses, gaols and hospitals, are not included in household estimates. 

This definition of a household is consistent with that used in the Census.

Household composition is used to describe and categorise households on the basis of the number of families present, and whether or not unrelated household members are present (if it is a family household), or the number of household members (if it is a non-family household).

The count of households is the number of households counted in the Census. It is not adjusted for undercount, dwellings containing overseas visitors, households of Australian residents where all members were temporarily overseas at the time of the Census, households of Australian residents where all members were not home on Census night and spent Census night in a non-private dwelling in Australia, and households of Australian residents where some members were not at home on Census night and were counted as a separate household elsewhere. Characteristics of households are available according to place of enumeration. 

Growth in the number of households.

The household population is the estimated resident population (ERP) that usually lives in private dwellings. It is the ERP less the population that usually lives in non-private dwellings.

Life expectancy refers to the average number of additional years a person of a given age and sex might expect to live if the age-specific death rates of the given period continued throughout his or her lifetime.

Living arrangement combines the three concepts 'relationship in household', 'family type' and 'household type'. It is used to describe the familial and non-familial relationship type of each person, within each family type, and within each household type.

A person who has no spouse or partner present in the household but who forms a parent-child relationship with at least one child usually resident in the household.

A person at least 15 years of age who lives in a dwelling on their own.

Non-private dwellings (NPDs) are residential dwellings with accommodation which are not included in the Census of Population and Housing list of private dwelling categories. NPDs are classified according to their function. They include hotels, motels, guest houses, prisons, religious and charitable institutions, military establishments, hospitals and other communal dwellings. Where this type of accommodation includes self-contained units (as provided by hotels, motels, homes for the elderly and guest houses), the units are enumerated as part of the NPD. Complexes such as retirement villages, which have a combination of self-contained units, hostel and/or nursing home accommodation, are enumerated as NPDs.

An occupied private dwelling is defined as the premises occupied by a household on Census night.

A family consisting of one parent with at least one dependent or non-dependent child (regardless of age) who is also usually resident in the family. The family type may or may not also include other related individuals.

A family of related individuals residing in the same household. These individuals do not form a couple or parent-child relationship with any other person in the household and are not related to any couple or one parent family in the household (if present). For example, a household consisting of a brother and sister only.

An individual who is related to at least one other member of the household, but who does not form a couple or parent-child relationship.

A person in a couple relationship with another person usually resident in the same household. The couple relationship may be in either a registered or de facto marriage, and includes same-sex couples.

A private dwelling (PD) in the Census is defined as a house, flat, part of a house, or even a room; but can also be a house attached to, or rooms above shops or offices; an occupied caravan in a caravan park or boat in a marina, a houseboat, or its own block of land. A caravan situated on a residential allotment is also classed as a PD.

Describes the familial and non-familial relationship of each person within each family in a given household. The familial relationship within each family is measured with reference to a family reference person chosen for that particular family.

Residents temporarily overseas are Australian residents who are overseas for a period less than 12 months.

Within each state and the Northern Territory, the area not defined as being part of the Greater Capital City is represented by a Rest of State region. The Australian Capital Territory does not have a Rest of State region.

The sum of age-specific fertility rates (live births at each age of mother per female population at that age) divided by 1000. It represents the number of children a female would bear during her lifetime if she experienced current age-specific fertility rates at each age of her reproductive life (ages 15-49).

These are structures built specifically for living purposes which are habitable, but unoccupied at the time of the Census of Population and Housing. Vacant houses, holiday homes, huts, cabins (other than seasonal workers' quarters) and houseboats are counted as unoccupied dwellings. Also included are newly completed dwellings not yet occupied, dwellings which are vacant because they are due for demolition or repair, dwellings to let and dwellings where all members of the household were absent on Census night.

Usual residence within Australia refers to that address at which the person has lived or intends to live for a total of six months or more in a given reference year.

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.