Auckland's population will be pushed over 1.5 million next week, Statistics New Zealand says.

And it's likely that will be a literal push, with the 1.5 millionth person likely to be a new baby.

"The 1.5 millionth person could be a migrant coming from overseas or from within New Zealand but it is most likely to be a new baby," population statistics manager Andrea Blackburn said.

"That's because births add more than net migration to Auckland's population growth."


Auckland had dominated the nation's population growth for the past 60 years and was most likely to hit the 1.5 million mark on February 1, Ms Blackburn said.

It had taken 35 years to jump from 500,000 to 1,000,000 but only 16 years to reach 1.5 million - and account for 34 per cent of New Zealand's population.

Auckland boasts the fifth-highest population in New Zealand and Australia, below Sydney, Melbourne, Brisbane and Perth but above Adelaide.