Aussie homes now the world's largest

It's a case of supersize me, and it's not about food.

New research shows that Australia has overtaken the United States to have the largest homes in the world.

While average US home sizes have shrunk for the first time in a decade due to global recession, the average floor space of new Australian homes hit a record high of 214.6 square metres in 2008/09 financial year, according to official data.

The Australian Bureau of Statistics (ABS) data commissioned by CommSec also showed the average floor area of new free-standing houses was also at a record high - 245.3sqm.

By contrast, the average size of new homes started in the US in the September quarter stood at 201.5sqm.

CommSec chief economist Craig James said the latest figures helped to explain how Australians were dealing with the shortage of housing - by making greater use of bigger homes.

"It is commonly believed that there is a housing shortage in Australia, we aren't building enough homes to accommodate our growing population," Mr James said in a statement.

"In fact, industry bodies believe that we are under-building by 50,000 homes a year. But the figures on home size and housing utilisation raise doubts about the extent of under-building in Australia."

ABS data showed that the average size of Australian households rose in the year to June 2008, from 2.51 people per home to 2.56 people.

"At face value, the increase in household size ... may not seem remarkable, but it appears to be the first increase in at least a century and perhaps the first since European settlement," Mr James said.

"It makes sense. Population is rising, as is the cost of housing and the cost of moving house, so we are making greater use of what we've got.

"Children are living at home longer with parents and more people are opting for shared accommodation."

The research showed homes in other parts of the world are far smaller.

Data from Europe shows that Denmark has the biggest homes (houses and flats) with an average floor area of 137 sqm, followed by Greece (126 sqm), and the Netherlands (115.5 sqm).

Homes in the UK are the smallest in Europe, at 76 sqm on average.