OzThe 23 millionth Australian, due to arrive this week, could be a baby called Jack or even a young Pom.

The Australian Bureau of Statistics says the nation's population is set to hit 23 million people on April 23 at 9.57pm (AEST), but there's only a 40 per cent chance he or she will be home grown.

Migrants make up 60 per cent of Australia's population growth and the UK accounts for one in five arrivals.

If number 23,000,000 is born locally, there's a slightly better chance of it being a boy, with 105 males born for every 100 females, and Jack their most popular name.

Australia's population is increasing by 1048 people per day, or by 1.7 per cent a year, which equates to one new Canberra or three new Darwins per year.

The ABS now forecasts the population will exceed 40 million in the late 2050s.

Australia's median age has increased nearly five years from 32.7 to 37.5.

Western Australia is the fastest growing state, while Tasmania's population growth rate is contracting.

Tasmania's population increased by just 500 people last year, while WA is now growing by more than 1500 people per week.

More people are moving interstate to Queensland, while NSW had the highest departures to other states, with 1900 people leaving each week.

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