"These types of landmarks are quite rare. Our population hit 3,333,333 in the mid-1980s and based on our projections, we probably won't get to 5,555,555 for another 30 years.
"It will also pass quite quickly. The population is currently growing by roughly 100 people every day, so it will only be at 4,444,444 for about quarter of an hour."
Mrs Blackburn said the population estimate is based on births, deaths, and migration since the census in 2006. At that time, the population was about 4.2 million.
Statistics NZ counts every person in New Zealand in the Census of Population and Dwellings. The census is usually held every five years, but because of the Canterbury earthquakes, the census that was planned for last year will now take place on 5 March 2013.
"It will be extremely interesting next year with the census to get new information on the location and composition of our population across the nation."