Australia's population has tipped over 27 million, around 18 years earlier than the milestone was predicted. 

The Australian Bureau of Statistics' (ABS) population clock ticked into the new million around 3.45pm AEST on Wednesday, January 24. 

The 624,100 population increase over the past 12 months is equivalent to adding the population of Tasmania (572,800) in just one year.

This annual growth is 41 per cent larger than the previous record when the population increased by 442,500 in 2009.

It also exceeds the Howard government's first inter-generational report forecast in 2002, which said the national population would not reach 25.3 million people until 2042.

This projection is reached by using the estimated resident population, as of June 30 last year, and assuming certain growth factors, such as one birth every minute and 42 seconds and one death every two minutes and 52 seconds. 

The assumptions are consistent with figures released nationally and by the states and territories, ABS says. 

Principal, Demographer & Futurist at McCrindle Research, Mark McCrindle, says the milestone was beyond modelling, and could mean exacerbated housing issues.  

"People are struggling around education, health supply.

"People trying to afford a home are really against it, even though there's government policies around new home construction." 

Migration surges population ahead post-pandemic 

While the 295,900 births and 189,900 deaths over the past 12 months remain similar to the historical averages, migration has surged Australia's population.

The recorded 737,200 overseas arrivals and 219,100 departures attributed to 80 per cent of the increase.

This growth is equivalent to one new Australian every 50 seconds.

If the growth rate persists, the next million could take less than two years with the 28 million milestone arriving in August 2025. 

"That's how quickly they're coming around these days, and I think getting a bit more moderation around that will be helpful," Mr McCrindle said. 

"Particularly to deal with the shortfalls already in housing supply relative to the demand." 

The spike comes after years of negative growth from migration when borders were closed during the coronavirus pandemic.

NSW and Victoria were also Australia's largest growing states, overtaking Queensland's growth during the pandemic years. 

"There was the decision made to ramp [migration] up and have a bit of catch-up," Mr McCrindle said. 

Looking forward, he said it was crucial for Australia to get back to "sustainable" growth.

"Trying to get the balance between a natural increase as well as migration," Mr McCrindle said. 

"We need new births, we need the young people in our population and the stimulation that provides long-term.

"As well as, of course, plugging skills gaps through migration."