Division reigns among the people of Sydney on the desirability of "denser" living, after new figures said the city's population will reach 6.4 million by 2036.

Modelling released by New South Wales Planning Minister Rob Stokes suggests 726,000 homes will be required in the next 20 years.

The projected growth in Australia's largest city — from 4.3 million in 2011 to 6.4 million in 2036 — was also a slightly higher projection than that made in 2014.

The modelling comes hot on the heels of a paper from think tank The Committee For Sydney entitled Making Great Places: Density Done Well.

Speaking to 702 ABC Sydney, committee chief executive Dr Tim Williams posed a question to listeners.

"Do they live in places where they can walk within 10 minutes to schools, green space, to jobs, services, cafes, bars and restaurants?

"If they say no, they're probably with two-thirds of Sydney ... we mustn't build an unhealthy city.

"If you drive 70 minutes to work every day, guess what that does to your family life?"

Dr Williams is a proponent of a denser city, and he has been backed by Mr Stokes who believes Sydney should be looking at the Barcelona model — medium density, mixed-use suburbs extending beyond the city centre.

The dream of a house and garden in the suburbs is increasingly out of reach for young Sydneysiders. ( Reuters: David Gray )

"We've got to be more thoughtful and conscious in our use of spaces," Mr Stokes said, adding that dense living provided lifestyle positives.

"There's a lot of people who have a love of the suburban lifestyle, but the way that that's been traditionally expressed is no longer really affordable."

Unsurprisingly, the issue of house prices struck a chord with the 702 audience.

Jenny: "I think it's a great idea, then my kids could maybe afford to buy a house somewhere close and not in another city or country."

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Dr Williams, who said denser living should not be conflated with high-rise living, said Sydney's urban sprawl was partly to blame for soaring property prices.

"It takes 13 times the average salary to get a home in this city and it's partly because we've been rejecting density.

"We're actually finding ways to prevent our own children from living closer to us."

Dr Williams said comparatively Sydney was not a very dense city; it is only 40 per cent the density of famously sprawling Los Angeles.

But many listeners were concerned with the idea of overcrowding.

Steve: "There isn't going to be more space on Bondi Beach or Manly Beach ... it's simply going to become more crowded."

Jerry: "If Wolli Creek is any example ... they're just going to put little boxes on top of each other and not add one iota of infrastructure."

Mr Stokes said growth should follow where infrastructure was provided, particularly public transport.

"A third [of growth] will take place in the traditional south-west and north-west areas, a third will occur along transport routes, and the other third will occur through the fabric of the rest of Sydney," he said.

The new figures also showed fewer people than ever before are leaving the city.

Some listeners called for people to be "directed" to regional centres, while others questioned migration levels.

Bob: "If we can have a plebiscite on equal marriage, why can't we have a plebiscite on what level of immigration we want?"

For Gordon from the Shire, the issue is simple: We are carried away with the "ideology of growth".

"I live in a different world to that. I live in a world where we have to be sustainable, we have to be able to respect the limits of the carrying capacity of the country we inhabit."

More information on the latest population projections in NSW can be found here.

