On Tuesday, the Australian Bureau of Statistics is set to reveal the full extent of the 2021 census, revealing increases in population size and changes in the make-up of Australian society.

Snapshot figures released to ACM show the population has jumped by almost 2 million people, with the official count now sitting at 25.5 million.

The 8.6 per cent rise compared to the 2016 census is despite normal migration patterns during the COVID-19 pandemic completely stalling migration.

Compared to a half-a-century ago, Australia has doubled its population.

Australia's Assistant Minister for Treasury Andrew Leigh said the 2021 census would be vital in designing and drafting policy responses to issues facing an array of communities.

"As a former economics professor, and an enduring stats nerd, I love the census. It helps us better understand the nation and helps us build better policy," Dr Leigh said.

Census data also showed Millennials were on track to take over Baby Boomers as the largest generation, both cohorts each respectively making up 21.5 per cent of the total population.

Nearly 40 per cent of the country indicated they did not follow a specified religion, an 8.8 per cent increase since the 2011 census.

Christianity made up the largest faith group at 43.9 per cent, with Catholicism being the largest denomination.

The 2021 census also included for the first time the leading ongoing health issues facing Australians and information relating to veterans.

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Australian statistician David Gruen said both sets of figures would assist in providing better insights, particularly in health.

"For the first time, we have data on long-term health conditions across the whole population," he said in reference to the introduction of long-term illness data.

"This is critical data to inform planning and service delivery decisions about how treatment and care is provided for all Australians."

The new collation of health data found the biggest long-term health issues facing Australians were asthma, arthritis and mental health.

More than 8 million people claimed they were living with an ongoing health condition.

Statisticians and demographers will also be analysing how the pandemic had changed population, migration and income trends.

The census also showed home ownership had stagnated over the last two decades, with only 66 per cent of households owning a home outright or with a mortgage.

That number was slightly down from the 1996 Census, when it was 67.8 per cent.

Outright home ownership fell sharply, dropping more than 10 percentage points from 1996. It now sits at 31 per cent.

Over that 25-year period, home ownership with a mortgage doubled.

There were also large rises in the number or people identifying as Aboriginal or Torres Strait Islander.

The ABS recorded a 25 per cent increase since the 2016 census, with 812,728 people identifying as Indigenous.

Almost half of Australians have one of their parents being born overseas.

India has overtaken China and New Zealand for Australians born overseas. It is now the third-largest country of birth behind Australia and England.

Mandarin was the most spoken language at home other than English, followed by Arabic and Punjabi.

Of the 5.5 million couple families recorded by the ABS, only 53 per cent had children living with them, while 2.5 million of them had children under the age of 15.

The ABS for the first time recorded more than 1 million single parent families and found four-out-of-five of those single parents were women.

Outside of Christianity, 2.7 per cent of the population practised Hinduism, while 3.2 per cent of the population followed Islam.