If Auckland was to continue to grow the way it has in the past, it would need an extra 293 square kilometres of residential land by 2038
A report by the NZ Institute of Economic Research (NZIER) shows the amount of residential land grew by 203 square kilometres between 1996 and 2013, but the city grew out, not up.
However, supply has not been able to keep up with demand. As a result, says the report, the average house price in the last four years has skyrocketed by 70 percent, from $555,573 in April 2012 to $975,000 in June 2016.
Auckland has the regions to thank for some of its booming population, which was 1.4 million according to the 2013 Census.
While its own population growth accounted for the appetite for housing, people moving from other areas of New Zealand to the City of Sails was also a big driver.
Statistics NZ's "medium" prediction is that by 2023, Auckland's population will hit almost 1.8 million, with 600,000 households.
NZIER says if land supply doesn't expand to match the increasing population, each suburb would need to increase its population by 50 percent.
"It would be better if Auckland's growth involved a combination of growing up and growing out. This would best contain house price growth and allow families to take advantage of local amenities or productivity opportunities by either moving to Auckland or remaining within the city limit."
How to grow Auckland is the subject of the Unitary Plan. Auckland Council will receive recommendations from the independent hearings panel on July 22, and then has 20 workings days to consider whether to accept them in full or part, or reject them.
Only 13 of the 66 territory authorities experienced a net gain of New Zealanders moving to that area.
Tauranga, Selwyn and the Queenstown Lakes District has the most rapid residential land growth.