Photo: RNZ
New Zealand's population is likely to reach six million before 2040, from the current 5.3 million, according to latest projections.
Stats NZ estimates two thirds of that growth will come from from international migration.
The projections released on Wednesday showed the population growing to about 7 million by 2060, and potentially nearly 8 million by the late 2070s.
Under a scenario with no migrant arrivals or departures, the population would peak in the early 2040s and then start to fall as deaths outnumber births.
"New Zealand's net migration has fluctuated widely from year to year," Stats NZ's Victoria Treliving said.
"But international migration has been the main contributor to New Zealand's population growth this century, and this is projected to continue."
The scenario of no migration in or out of New Zealand was unlikely, but helped show the impact of migration on population growth, Treliving said.
"Natural increase is no longer the main driver of New Zealand's population growth."
A much older population is also predicted, with the number aged 65 and over likely to reach one-million by 2029.
"The number of people aged 65 years and over is currently increasing by more than 500 people a week," Treliving said.
One in six New Zealanders is in that age group at present, and by the mid-2030s this would be one in five.
The median projection assumes on average:
- a net migration gain of 42,000 people a year over the next 50 years
- fertility rates easing from 1.59 births per woman in 2025 to 1.55 in 2051
- life expectancy at birth increasing from 80.8 years and 84.0 years respectively for males and females in 2025, to 88.1 years and 90.5 years respectively in 2078
