Natural increase - births minus deaths - is projected to account for three-fifths of Auckland's growth, and net migration the remaining two-fifths.
The population in the City of Sails is projected to reach two million in the early 2030s - meaning out of every 100 people in New Zealand, 37 would live in Auckland by 2028, and 40 by 2043. That's up from the current 34 out of 100.
Auckland's growth would account for three-fifths of the national population growth between 2013 and 2043, StatsNZ said.
Of New Zealand's 67 territorial authority areas, 51 are projected to have more people in 2028 than in 2013. However, only 30 are projected to have more people in 2043 than in 2028.
The fastest population growth between 2013 and 2043 is expected in Selwyn and Queenstown-Lakes districts, up an average of 2.2 per cent and 1.8 per cent a year, respectively, StatsNZ said.