When New Zealand turns old

The shape of a country

In 1950 New Zealand had 1.9 million people and a median age of 29. Fewer than one in ten were 65 or over. Then came the boom. By 1961 a third of the population was under 15 and there were 57 children for every 100 people of working age, the highest child dependency ratio on record. The median age kept falling, and bottomed out at 25.6 in 1970. Half the country was under 26.

The number of children peaked in 1974 at just under 940,000 and then fell for 15 years, to 770,000 in 1989, as fertility slid towards two births per woman. That is the moment the pyramid stops being a pyramid. The base narrows while the bulge of the boomers moves up through the working years, and the shape becomes a barrel.

The barrel years were kind to the country’s arithmetic. By 2006 every boomer was of working age and hardly any had retired. The total dependency ratio, which counts children and over-65s together per 100 people aged 15 to 64, fell to 50, its lowest level since the 1930s. Stats NZ calls this out in its own commentary on the projections, and it is worth pausing on, because the ratio is now heading back to where it was in the early 1960s. The difference is that in 1961 more than two thirds of the dependants were children. In 2078 more than two thirds will be over 65.

What the boomers did and did not do

It is tempting to read this as a boomer story. Stats NZ is careful to say it is not. In its June 2025 release the agency wrote that “Population ageing is not caused by the baby boomers (generally considered as those born in 1946 to 1965), but by the transition to lower birth rates and lower death rates.” The boomers make the change lumpy and visible. They do not cause it. The same release adds that “once the baby boomers have moved through the age structure, the New Zealand population will not revert to a younger age structure – barring major changes in childbearing patterns (fertility rates).”

You can see that in the chart. Scroll past 2060, when the last boomers have largely left the top bars, and the column does not narrow again. It is simply the new shape.

Why the median age stalled

The median age of New Zealand rose from 25.6 in 1970 to 37.6 in 2013 and then stopped. At 30 June 2025 it was 38.2, barely a year higher than 12 years earlier. That pause is the one part of the chart that is not about births or deaths at all.

Stats NZ attributes it to migration. The median age “has hovered around 37 to 38 years since then as significant net migration – concentrated at ages 18 to 39 years – contributed to population growth and postponed the increase in the median age.” Net migration hit a record 135,500 in the October 2023 year, and the 2024 base population used for the projections came in 110,800 people higher than the previous projection had assumed, mainly because of it. You can watch those arrivals in Newswire’s migration tool, which traces every month of arrivals and departures since 2001.

The pause is over. Stats NZ expects “A median age of 40 years is likely to be reached in the early 2030s.” On the median projection it happens in 2031. By the mid-2060s there is, in the agency’s words, “a 3 in 4 chance that half of the population will be older than 45 years.”

Fewer babies

The first of the two forces behind the chart is fertility. For 40 years from 1976 New Zealand’s total fertility rate, the number of births a woman would have over her life at current rates, sat in a band between 1.9 and 2.2. Then it dropped. Stats NZ records a fall from 1.87 in 2016 to 1.55 in 2024. The projections assume it settles at 1.55 for the long term, down from the 1.65 assumed in the previous two rounds. Completed family size tells the same story more slowly. Women born in the early 1950s averaged 2.5 children. Women born in the early 1970s averaged 2.1.

Newswire’s births tool shows how that happened, year by year and age by age, as the peak childbearing age moved from the early 20s to the early 30s and the total came down with it.

Births still average about 60,000 a year in the projections for the next two decades, compared with about 57,000 in the June 2024 year, partly because the number of women of childbearing age is still growing. But the number of children under 15 barely moves. The median projection has it fluctuating between 0.92 and 1.03 million all the way to 2078, while everything above it grows. Children were 33 percent of the country in the early 1960s and 18 percent in 2024. Stats NZ expects “around 15 percent in the 2040s and around 13 percent in the 2070s.”

Living longer

The second force is survival. Under the median assumption, life expectancy at birth rises from 80.8 years for men and 84.0 for women in 2025 to 88.1 and 90.5 in 2078. That is a gain of about a month and a half of life every year.

The effect is concentrated at the very top of the chart. There were 95,000 New Zealanders aged 85 and over in 2024. Stats NZ puts the 2051 figure at between 275,000 and 322,000, and the 2078 figure at between 459,000 and 628,000. On the median projection there are half a million people over 85 by the late 2070s, more than the entire population of Wellington city today. By the 2050s, the agency says, “about 1 in 5 people aged 65+ will be 85+, compared with around 1 in 9 in 2024.”

Three workers for every retiree

The number demographers watch most closely is the ratio between people of working age and people over 65. In the mid-1960s there were about seven people aged 15 to 64 for every person 65 and over. In 2024 there were 3.9. Stats NZ expects “about 3.1 people aged 15 to 64 years in 2038, 2.8 in 2051, and 2.0 in 2078.”

Year	Population	Median age	Under 15	65 and over	People 15 to 64 per person 65+
1950	1.91m	29.4	29.0%	9.1%	6.8
1961	2.43m	27.1	33.0%	8.6%	6.8
1989	3.33m	30.8	23.3%	10.9%	6.0
2006	4.18m	35.8	21.2%	12.2%	5.4
2025	5.32m	38.2	18.2%	16.9%	3.8
2031	5.66m	40.1	16.6%	19.0%	3.4
2043	6.28m	42.7	15.0%	21.2%	3.0
2057	6.94m	45.0	14.3%	24.3%	2.5
2078	7.83m	47.8	13.1%	28.6%	2.0

Rows in brown are the Stats NZ 2024-base median projection. Estimates to 1995 are UN World Population Prospects 2024, from 1996 Stats NZ.

Stats NZ attaches a caution to that ratio which deserves repeating in full. “For those aged 65+, the term ‘dependency’ does not necessarily imply financial or economic dependency, given people are progressively living longer, are healthier, and are working longer.” A 67-year-old in 2040 is not a 67-year-old in 1970. The ratio measures age structure, not who is paying for whom. But age structure is what superannuation, health budgets and the labour market are built on, and it is moving in one direction.

When deaths overtake births

The most striking crossing in the projections is one the country has already started to feel. Natural increase, births minus deaths, was about 20,000 in the June 2024 year. In the year to June 2026 it was 18,700, which Stats NZ said in August was “the lowest increase since the early 1940s, during World War II.” Deaths are rising because more people are reaching the ages where most deaths occur. From about 38,000 in 2024, Stats NZ expects annual deaths to pass 40,000 by the early 2030s and 50,000 by the mid-2040s.

On the median projection the two lines meet around 2057, and from then on New Zealand has more funerals than births in a typical year. Stats NZ puts it more cautiously. “By the late 2040s, there is roughly a 1 in 4 chance of natural decrease – more deaths than births.” Either way, at some point in the middle of this century every bit of population growth New Zealand gets will come from migration.

What could change it

Stats NZ ran six alternative scenarios alongside the median, and they are the most useful part of the release for anyone tempted to think the trend can be turned around.

Very high fertility, meaning a return to 2.1 births per woman by 2040 and staying there, is the only scenario that produces a noticeably younger country. Even then the median age still rises, to almost 42 by the mid-2050s. Very high migration, a net gain of 100,000 people a year from 2028, gets the population to 7 million by 2040 and 11 million by 2073, but the median age in 2078 is 45.8 years against 47.8 in the median projection. The agency’s explanation is one sentence long. “This reflects that migrants inevitably age as well.”

The no migration scenario shows what the country would do on births and deaths alone. The population peaks at just under 5.5 million in the early 2040s, returns to today’s 5.3 million around 2060, and is under 4.9 million by 2078, with a much older age structure than any other scenario. And a scenario in which net migration swings by tens of thousands either side of the median on a ten-year cycle ends up within 16,000 people of the median in 2078. Migration decides how many New Zealanders there are. It changes the shape of the pyramid far less than most people assume.

What the chart does not tell you

These are projections, not forecasts, and Stats NZ says so repeatedly. The median is the middle of thousands of simulations. The 90 percent range for total population in 2078 runs from 6.6 million to 9.0 million, and for the share aged 65 and over from 25 percent to 33 percent. Fifty years is a long time, and a pandemic, a policy change or a shift in what people want from family life can move the numbers.

What the range does not include is a version of the future in which New Zealand gets younger. Every percentile and every scenario has the median age higher in 2078 than it is now, and the share over 65 larger. The only questions are how far and how fast. The next thirty years are already largely written, in the birth certificates of people who are alive today. What the country decides to do about it is not.