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NSW Department of Planning, Industry and Environment
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PopulatioNSW update

PopulatioNSW provides regular updates and analysis of population data for New South Wales.


From March 2017, the PopulatioNSW / demography news is a part of the Department of Planning and Environment's monthly newsletter. To receive monthly updates on demography, research and economics, sign up to the Department's monthly newsletter below.


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Drivers of population change need to inform planning because they tell us whether we need to plan for preschools or retirement villages, one-bedroom apartments or three-bedroom houses.  This information tells planners what they need to know about demography and population trends in NSW.

Population and sub-populations can change through only three processes: fertility (the number of babies born), mortality (the number of people who die), and migration (the number of people who move from one place to another – between countries, states or local government areas ).  Demography is the statistical study of how these processes change over time and their impact on population size and composition.  For more information on how these factors have  affected the NSW population since the early 1970s, visit our Population Projections page.

ERPs and population projections for NSW and LGAs are for usually resident populations.  Usual residents are defined as people living in one place for six months or more.  Therefore, the ERPs and projections do not include temporary visitors, such as tourists or fly-in, fly-out, or drive-in drive-out workers.

The total fertility rate (TFR) measures the number of children born to a woman if she lived through her childbearing years and bore children at the same ages and rate as current age-specific fertility rates show.  

A replacement TFR is 2.1 births per woman, the number of births needed for one generation to replace itself.  In NSW, fertility has been below replacement since 1976.  

The number of babies born in NSW is based on the TFR and the number of women who are of childbearing age (15-49 years).

Lower fertility affects population change in two ways:

  • it can slow growth that comes from natural increase (or the difference between births and deaths)
  • it is a driver of population ageing (because fewer births create smaller birth cohorts in relation to larger, older generations).

Lower fertility can be offset by migration. Not only do new people moving into an area increase population size in the same way as new babies do, but migrants are mostly aged in their 20s and 30s, which are the ages when people are most likely to have a family. This means new arrivals in an area can have a cumulative impact on population growth. This can also help to lessen the impact of an ageing population. The opposite is also true, where out-migration can exacerbate ageing because the people most likely to have babies are more likely to leave.

Demographers use net migration to summarise population mobility. This is the difference between the number of people who arrive and the number of people who leave an area. It is measured at different geographic scales.


In NSW, net overseas migration has historically been positive (more people arriving from overseas than leaving Australia).


Net overseas migration gains include:

  • people migrating permanently to Australia
  • people coming to Australia for education courses that last longer than a year
  • people coming to Australia for work for a year or more
  • returning Australians who have been overseas for a year or more and have decided to come home.


NSW has historically had more people leaving the state for other parts of Australia than arriving. The biggest out-migration flows have been from New South Wales to Queensland. Net migration can also be measured for each LGA in NSW, with small rural areas often losing population through migration.

Different fertility, mortality and migration patterns across NSW mean different growth patterns. Migration is one of the most important drivers of change because it can change very quickly and different types of net migration sometimes offset each other.

For example, Sydney attracts overseas migrants, but a lot of the interstate migration loss experienced by NSW is because people leave Sydney for other states in Australia. There is also constant movement between Sydney and the regions of NSW.

While the projected size of a population at some date in the future may change as new information becomes available, what is causing the change will most likely remain the same.  

The majority of people who are part of the population projection, and who we are planning for, have been born and have been part of demographic modelling for all the years since their birth or arrival in Australia.

Baby Boomers, for example, will continue to get older through all population projection reviews.

Planners need to take account of the number of people in any one place, as well as the age of people who live there.


Age is the most critical determinant of demographic activity and many other important life events such as going to school or university, starting a job or retiring, buying a home and starting a family.


Key aspects of demographic change remain consistent over time:

  • migrants (overseas and internal) will predominantly be people aged in their 20s and 30s
  • women can only have babies at certain ages
  • people are more likely to die when they are old.


These certainties are important evidence to inform planning and a singular focus on population size can mask important changes in age structure and the subsequent impact of fertility, mortality and migration.

Historical patterns of higher growth in Sydney compared to elsewhere in NSW will continue into the future. This is driven by a younger age structure, with more women at childbearing ages as well as growth from overseas migration.  

Centres outside Sydney will have the most significant ageing.  For many small places where the out-migration of young people means more people are leaving than arriving, this can lead to population decline in a very short space of time.  

For large regional centres, birth rates and migration gains mean continued growth alongside relatively more people in the older ages.

Page last updated: 16/12/2019