One in 10 Australians has been homeless at least once in their lives, new research has found, making it a much more common experience than previously suspected.
RMIT researchers have found that 11.1 per cent of women and 15.1 per cent of men have been homeless at least once in their lives, meaning 2.35 million Australians have experienced at least one night without secure housing.
Of those, 1.4 million - or 500,000 women and 900,000 men - have also slept rough or in improvised dwellings at some point. 
The data is backed up by the latest Bureau of Statistics General Social Survey, which was released in   July and states that 2.5 million people aged 15 and over have experienced homelessness at some time in their lives. Of those, about two-thirds had not sought help from government or charity groups.
The study increases the definition of homelessness and includes a person living in an inadequate dwelling, has short or no tenure and "does not allow them to have control of, and access to space for social relations".
Professor Chris Chamberlain and Dr Guy Johnson, from the Centre for Applied Social Research, said the report contradicted the assumption that only a small number of homeless people have slept rough.
"The statistics are startling because they are so unexpectedly high. Nobody had any idea that the numbers were this big."
A long-standing myth, that the long-term homeless are the most likely to sleep rough, was quashed, with the research showing that it is people homeless for four or fewer weeks who are most likely to lack a roof over their heads.
Defining sleeping rough as including sleeping in a car or staying in an empty or derelict building or public place, such as a park, researchers found that 59 per cent of homeless people had done so at some point.
Of those who have been homeless, research found that for just over half (53 per cent), it was a one-off experience, but 25 per cent had been homeless at two separate times and 22 per cent had been homeless three or more times. Men were more likely to be homeless multiple times.
"People who have a short-term problem, particularly those from the outer suburbs, as well as in regional centres and country towns, often have no knowledge of [available services]  and do not 'hang out' where the homeless congregate in the capital cities," the research stated.
Homelessness Australia chief executive Glenda Stevens said the research 
 "should be a big wake-up call to the government".
 "Without taking real steps to address the chronic lack of affordable housing, and considering the impact of funding that does not properly resource services, this number is only going to rise," she said.
Researchers surveyed 1349 people and compared their findings to the 2011 census.
Professor Chamberlain said there were multiple faults with the census data, one of them being the fact it is collected during winter, when there are typically fewer people sleeping rough.
"The 2011 census counted just 6800 rough sleepers, but crucially, the census does not ask if people have ever experienced homelessness," he said. "Most people are hiding away for warmth and, of course, hiding away for safety."
He said the short-term homeless were likely to be under-represented and that traditional research failed to question how long a person had been homeless.
The latest research echoes overseas studies revealing 14 per cent of Americans and 13.9 per cent of Britons had been homeless at least once in their lifetime.
Jenny Smith, chief executive of the Council to Homeless Persons, said the figures were "truly astonishing" but were backed up by the most recent  Bureau of Statistic General Social Survey.
"We know that much homelessness is hidden and easy to overlook in the census process. For example, people couch-surfing may feel too ashamed to reveal their homelessness to the friends with whom they're staying," she said.