In the wee small hours of Tuesday, Australia's population clock will tick over to 24 million.
The milestone follows record overseas migration, which made up more than half of Australia's population increase in the year before July 2015, according to the Australian Bureau of Statistics.
"Australia had record levels of migration about five to seven years ago," ABS forecaster Andrew Howe told AAP.
"That has slowed down a little bit in the past two or three years."
There's also been a small decrease in the number of children being born, with the current fertility rate sitting at 1.8 children for each Australian woman.
"In terms of trends, that's actually come down a little bit over the past few years, but compared to 10-20 years ago that's actually higher," said Mr Howe.
Australia's population increases by one person every one minute and 31 seconds after accounting for births, deaths and international migration.
There were nearly twice as many births (304,000) as deaths (155,000) last financial year.
Mr Howe says Australia's annual population growth rate is 1.4 per cent, relatively high compared to the rest of the world.
New Zealand and the United States both have a growth rate of 0.7 per cent, the United Kingdom's is 0.6 per cent and China's is 0.5 per cent.
Japan's rate is actually decreasing, recording an estimated 0.2 per cent decline in population last year.