Population aged 18 and older

IBISWorld forecasts the population aged 18 and older to increase by 1.7% during 2025-26, to reach 22,189,796 people. The number of Australians born in 2007-2008, which will transition into this age demographic in 2025-26, was a record at the time, driving the increase in this demographic's population.

In general, the birth rate tends to be more volatile than overall population growth, with birth rates demonstrating periods of both growth and decline. However, the birth rate trended upwards between the 1980s and the lates 2000s, contributing to the long-term growth in the population aged 18 and older. In addition, life expectancy in Australia has continued to improve, supporting growth in the population demographic at the later end of the demographic spectrum.

Over the past five years, the population aged 18 and older has grown at an unusually volatile rate. While the demographic's population has increased every year, the pandemic caused a temporary blip, with the demographics growth rate stabilising at 0.1% in 2020-21. As international students and migrants flocked back to Australia after the borders reopened, growth in the number of people aged over 18 reached record levels across 2022-23 and 2023-24. As these initial post-pandemic effects have worn off in 2024-25 and 2025-26, the growth rate of people aged over 18 in Australia has returned to a level mirroring historic averages. Overall, IBISWorld forecasts the population aged 18 and older to grow at a compound annual rate of 2.1% over the five years through 2025-26.