National Population Projections 2024-base

Projection assumptions Projection assumptions are formulated after analysing short-term and long-term historical trends, recent trends and patterns observed in other countries, and government policy. Main changes since the previous 2022-base projections Deriving the projections involved a review of all projection assumptions. The following are the main changes from the previous 2022-base projections. Base population The base population is 5.290 million (provisional) at 30 June 2024 (National population estimates: At 31 March 2025 (2023-base)) This is 110,800 (2.1 percent) higher than the 2022-base median projection for 2024. Fertility The long-term median period total fertility rate is assumed to be 1.55 births per woman, compared with 1.65 in the 2020-base and 2022-base median assumption. Mortality Under the median assumption, life expectancy at birth for males and females increases from 80.8 and 84.0 years in 2025, to 88.1 and 90.5 years in 2078, respectively. The life expectancy at birth in 2078 is about 0.5 years higher than the 2022-base median assumptions, but close to the 2020-base median assumptions. Migration Following COVID-19 pandemic border restrictions in 2020 to 2022, the easing of border restrictions through 2022 and immigration policy settings (including the 2021 Resident Visa) resulted in net migration reaching a record 135,500 in the October 2023 year. Net migration then progressively dropped to 26,400 (provisional) in the March 2025 year (International migration: March 2025). In the short term, median annual net migration is assumed to be 25,000 in the June 2025 year and 30,000 in the June 2026 year, gradually rising to 37,500 in the June 2031 year, 42,500 in the June 2051 year, and 49,250 by the June 2078 year. This is equivalent to a direct gain from net migration of 2.277 million over the 54-year projection period 2025 to 2078, compared with 1.341 million over the same period from the 2022-base projections. Base population New Zealand’s base population as at 30 June 2024 is 5.290 million (provisional). It incorporates results from the 2023 Census of Population and Dwellings and the 2023 Post-enumeration Survey (a sample survey to measure census coverage). This base population is 110,800 (2.1 percent) higher than the 2022-base median projection for 2024, mainly reflecting the higher than assumed net migration during the June 2023 and 2024 years. Estimated resident population (2023-base): At 30 June 2023 and Estimated resident population 2023: Data sources and methods has more information about the base population. The estimated resident population (ERP) is the best available measure of the number of people usually living in New Zealand. The ERP at 30 June 2023 includes estimates of uncertainty from contributing data and estimation processes, where possible. The main source of uncertainty in the ERP was the estimated net census undercount measured by the 2023 Post-enumeration Survey. However, the process did not incorporate uncertainty around data quality in individual sources or from adjustments made to the ERP at 30 June 2023. As not all sources of uncertainty in the ERP are measurable, some wider uncertainty in the base population has been assumed for projection purposes. The uncertainty is assumed to vary by age and sex, broadly consistent with that measured in the June 2023 ERP, and reflects the combined uncertainty from three sources: Census enumeration and processing: Coverage errors may arise from non-enumeration and mis-enumeration (for example, residents counted as visitors from overseas and vice versa), either because of deliberate or inadvertent respondent error. Errors may also arise during census processing (for example, misrecognition during scanning, uncertainty from age imputation). Adjustments in deriving population estimates: This includes the adjustments applied in deriving the ERP at 30 June of the census year (for example, net census undercount). It also includes uncertainty associated with the post-censal components of population change (for example, births, deaths, and net migration between the census date and 30 June). Migration estimates for more recent months have greater uncertainty and are therefore subject to larger revisions than estimates for earlier periods. Estimated net migration is a gain of 70,400 (provisional) for the June year 2024 (based on estimates published in May 2025). These estimates could be revised up or down, before final estimates are published in December 2025. See International migration releases for more details. Simulations of the base population are produced by drawing a random number sampled from a normal distribution with a mean of zero. For each simulation, a random number is multiplied by the assumed standard error for each age-sex then added to the base ERP. Fertility Fertility assumptions are formulated using birth registrations, period and cohort fertility rates, census data on children ever born (including rates of childlessness), and international comparisons. The median period total fertility rate (TFR) is assumed to be 1.59 in 2025 then gradually decrease to 1.55 in 2054 and beyond. The median assumption is not an assumed trajectory, but the median of the fertility simulations that vary every year around that median. In the 40 years from 1976 to 2015, the period TFR was generally in the range of 1.9 to 2.2 births per woman. However, the TFR dropped from 1.87 in 2016 to 1.55 in 2024. The TFR is not a measure of true family size as it is affected by the timing of births. The cohort TFR indicates a progressive decline in completed family size. Women born in the early 1950s averaged 2.5 births each, compared with 2.1 for those born in the early 1970s. Census data (1981, 1996, 2006, 2013, 2018, and 2023) on the number of children ever born also indicates progressive declines in completed family size and progressive increases in childlessness. Internationally, TFRs are generally declining, or are already lower than in New Zealand. New Zealand’s TFR has historically been one of the highest among Organisation for Economic Co-operation and Development (OECD) countries. Even with the recent decline in New Zealand’s period TFR, it remains above the OECD average. Age-specific fertility rates (ASFRs) are assumed to vary throughout the projection period. Between 2024 and 2054, the median ASFRs decline for women aged under 30 years and increase for women aged 30 years and over. Simulations of TFR are produced using a simple random walk with drift model. Random errors are sampled from a normal distribution with a mean of zero and a standard deviation of 0.0556. The standard deviation is derived by fitting an autoregressive integrated moving average or ARIMA(0,1,0) model to annual TFR for 1977 to 2024 June years. The drift function shifts the median of the TFR simulations to follow the assumed median TFR. Median ASFRs are scaled to sum to the simulated TFR. Simulations of the sex ratio at birth for each year are produced by drawing a random number sampled from a normal distribution with a mean of 105.5 males per 100 females and a standard deviation of 1.0. The mean and standard deviation are calculated from historical data for 1900 to 2024 December years (New Zealand cohort life tables: March 2025 update). Future fertility trends are uncertain and depend on a range of factors, including: changes in population composition and different trends in subpopulations (including ethnic groups) trends in ideal family size and the strength of individual desires for children trends in the patterns of education and work, including the timing, duration, and proportion of time dedicated to those activities changing macro-level conditions (for example, government policies, childcare facilities, and housing) that influence the cost of children in a broad sense changing nature and stability of partnerships, including rates of partnership formation (including re-partnering) and dissolution changing biomedical conditions (for example, female fecundity, new methods for assisted conception). Mortality Mortality/survival assumptions are formulated using death registrations, period and cohort mortality rates, and international comparisons. Death rates are assumed to vary throughout the projection period, with the assumptions driven by trends in age-sex death rates. Life expectancy assumptions are not explicitly formulated but are derived from the assumed death rates. Male and female age-specific death rate assumptions are formulated using a coherent functional demographic method (FDM) developed by Hyndman, Booth, and Yasmeen (Coherent mortality forecasting: The product-ratio method with functional time series models, 2012). This method builds on the FDM of Hyndman and Ullah (Robust forecasting of mortality and fertility rates: A functional data approach, 2007), which is itself an extension of the Lee-Carter method widely used in mortality forecasting. Their research and that of Booth, Hyndman, Tickle, and de Jong (Lee-Carter mortality forecasting: A multi-country comparison of variants and extensions, 2006) indicates that FDM forecasts are more accurate than the original Lee-Carter method and at least as accurate as several other Lee-Carter variants. The advantage of the coherent FDM is that it ensures male and female assumptions do not diverge over time (see Forecasting mortality in New Zealand). The coherent FDM uses smoothed historical data to fit the model, which is then forecast using ARIMA and autoregressive fractionally integrated moving average (ARFIMA) time-series models. The historical data is derived from Stats NZ’s cohort mortality series (New Zealand cohort life tables: March 2025 update), transposed to give period death rates for each age for 1967 to 2024 June years. Simulations of death rates are produced using an ARIMA(0,2,2) model to give plausible uncertainty bounds. The median assumption has period male life expectancy at birth increasing from 80.8 years in 2025 to 85.0 years in 2051 and 88.1 years in 2078. The corresponding female period life expectancy at birth is 84.0 years in 2025, 87.7 years in 2051, and 90.5 years in 2078. The median assumption has a male cohort life expectancy at birth of 76.2 years for those born in 1949 and 88.5 years for those born in 2024. The corresponding female cohort life expectancy at birth is 80.5 years for those born in 1949 and 91.1 years for those born in 2024. Despite differences in methods, the New Zealand life expectancy assumptions are broadly consistent with those in other countries. Mortality reductions are expected to continue in the future, although the extent of the trends is uncertain and depends on: changes in population composition and different trends in subpopulations (including ethnic groups) changes in biomedical technology, regenerative medicine, and preventative methods including monitoring, treatment, and early intervention changes in health care systems including effectiveness of public health changes in behaviour and lifestyle (for example, smoking, exercise, and diet) changes in infectious diseases and resistance to antibiotics environmental change, disasters, and wars. Migration Migration assumptions are formulated using international migration data (including migrant arrivals and migrant departures by country of citizenship and age), immigration applications and approvals, immigration policies (in New Zealand and other countries), and an expert elicitation survey. In March 2025, we conducted a survey to elicit the opinions of migration experts on future net migration levels. This survey was based on an approach developed by Statistics Canada (see 2018 Survey of Experts on Future Demographic Trends). The survey was used for the first time to inform the migration assumptions of our 2020-base national population projections, and repeated for the 2022-base national population projections. For the 2025 survey we invited input from about 300 different people from central government agencies, central and regional forecasting networks, and population specialists. Survey results show that migration experts expect lower net migration levels in the short term (2026 June year) than in 2023 to 2024, with a 50 percent chance of net migration between 23,000 and 35,000. In the medium term (2031 June year), respondents expect median net migration between 26,000 and 44,000, increasing to between 30,000 and 56,000 in the longer term (2051). In contrast to previous surveys, the median response was for higher net migration over the projection period. Respondents indicated more uncertainty in the long-term net migration, as reflected in a wider range of survey responses. For these 2024-base projections, migration simulations are assumed to vary throughout the projection period. However, the median net migration (migrant arrivals less migrant departures) assumption gradually increases over the projection period: 25,000 in 2025 30,000 in 2026 32,500 in 2027 34,500 in 2028 36,000 in 2029 37,000 in 2030 37,500 in 2031 and increasing linearly by 250 a year to 42,500 in 2051 and 49,250 in 2078. The median assumption is not an assumed trajectory, but the median of the migration simulations, which vary every year around that median. The net migration assumptions are consistent with the results of the expert survey. These assumptions are for a gradually increasing median net migration gain over both the short term and longer term. This is equivalent to a net migration rate of about 6.4 per 1,000 population over the projection period. New Zealand’s net migration average and long-term trend are sensitive to the start and end points. However, annual net migration has averaged 25,000 to 30,000 from the 1990s and averaged 32,200 in the 2002 to 2024 June years. The distribution of net migration by age-sex reflects historically observed patterns. Generally, migration is dominated by migrant arrivals and migrant departures at ages 18 to 39 years. Recent migration has been spread more broadly, including significant flows among those aged under 18 and 40 to 44 years. Future migration trends are uncertain and depend on a range of factors in source and destination countries, including: changes in immigration policy (in New Zealand and other countries) changes in the main motives for migration (for example, work, family reunification, education, asylum, and retirement) changes in migration pressure in source countries (for example, population growth and economic growth) changes in the attractiveness of New Zealand as a place to live (for example, work opportunities, economic conditions, wages relative to costs and other countries, and settlement and integration practices) costs of migration, including cost of travel and existence of networks and pathways that facilitate migration environmental change, disasters, pandemics, and wars. Simulations of net migration are produced using an ARIMA(1,0,1) with drift model. The autoregressive and moving average parameters are derived by fitting an ARIMA(1,0,1) model to annual migration for 1988 to 2024 June years. The drift function shifts the median of the net migration simulations to follow the assumed median net migration. Net migration by age-sex is interpolated between a high and low pattern, to sum to the simulated net migration level. In the long term, there is an assumed 50 percent chance in any year that net migration will be within ±21,600 of the median, and a 90 percent chance within ±52,700. This compares with ±18,600 and ±45,300 from the 2022-base assumptions. en-NZ