Stats NZ, based on forecasts around births, deaths and net migration, estimates that the country’s population increases by one person every five minutes and 26 seconds.
The four-million milestone was reached back in 2003, Dunstan said, adding over the last few years, the population has grown particularly quickly.
“In the year ending September 2018, the population had grown by 90,000,” he said, adding it was growing as fast as 2.1 per cent in 2016 and 2017.
New Zealand’s population reached one million in 1908, while the second million was reached in 1952.
According to Stats NZ, the population hit three million in 1973 and four million in 2003.