Sydney will need more than 600,000 extra homes for an additional 1.6 million people in the next two decades, according to state government figures.
But urban planners say the projections also reveal the ''real tension'' in matching population growth to the right housing stock as Sydney also contends with the growing challenges of an ageing population.
Figures published on Thursday by the Department of Planning and Environment predict an additional 2 million people are expected to call NSW home by 2031, when the state's population will reach 9.2 million.
About 5.9 million people are expected to live in Sydney - 100,000 more than last year's preliminary forecasts - requiring an additional 664,300 homes.
Two babies are expected to be born for every person who dies in NSW, where three overseas migrants will arrive for every resident who departs for another state.
Even so, single households will be the fastest growing type, increasing by more than 40 per cent across the state as the population ages.
They will also remain - or increasingly become - the most common group within the inner Sydney area bounded by Ashfield, Botany and Mosman. It is in stark contrast to the trend in Sydney's west, where families are expected to remain the most common household type.
Bill Randolph, director of the city futures research centre at the University of NSW, said this could lead to a ''real tension'' if older households did not downsize.
''I think we could have big mismatch,'' Professor Randolph said. ''There will be a single aged people still living in their old home, yet the young families being pushed out.''
Despite the population boom putting the squeeze on the City of Sydney childcare centres and high schools, families will still only comprise 13,600 of its 155,950 households by 2031.
While this is double the number recorded in 2011, lone households - comprising young professionals, student or older singles - will increase by 25,000 in the same period to more than 67,000.
At the same time, the city's population of 273,500 is projected to skew older, with the number of people aged 65 and above expected to almost triple.
''We are going to see a city with [a] very significant proportion of older people,'' said Professor Peter Phibbs, the chairman of Urban and Regional Planning and Policy at the University of Sydney. Planning needed to ''think hard'' about designing an age-friendly city, he said, as well as the types of housing available.
''We need a planning system that will help facilitate housing production at a range of price points - the current focus on just hoping that expanding supply will fix everything will not succeed,'' he said.
Ashia Levique, 40, has lived happily on her own in Darlinghurst for the past six years.
Ms Levique, who works in banking and finance, did not mind if resources were directed locally into family friendly services and facilities, saying all her needs were catered for in the area.
''In 20 years' time I'll probably be asking for more pensioner activities and bingo halls,'' she said.