Subnational Population Projections 2023-base

Projection assumptions for fertility, mortality, and migration are formulated after analysing short-term and long-term historical trends, information provided by local planners, and government policy. The Subnational population projections, projection assumptions, 2023(base)–2053 table in the Subnational Population Projections area of Aotearoa Data Explorer provides a summary of the low, medium, and high projection assumptions for each area. Summary of main changes from the previous 2018-base subnational population projections Deriving the projections involved a review of all projection assumptions with the latest subnational population estimates taken into account for the first 5-year period. The following are the main changes at the national level from the previous 2018-base projections (released 12 December 2022). The base population is 5.20 million at 30 June 2023 (2023-base population estimates). This is 50,600 (1.0 percent) higher than the 2018-base medium projection for 2023. 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 assumptions. Life expectancy for 2053 is slightly higher (five months and two months respectively) than the previous median assumptions. The average annual net migration between 2023 and 2053 is 39,700 under the median assumption, compared with 24,100 in the previous projections. Geographic classification The population projections in this release are based on the regional council, territorial authority, and Auckland local board boundaries at 1 January 2025. Geographic boundary viewer can be used to view these boundaries. Fertility The assumed fertility rates are based on the expected number of births for each area for the first five-year period (2024–2028), which is primarily based on birth estimates in 2024–2025, with change between 2029 and 2053 consistent with the fertility assumptions from the National population projections: 2023(base)–2078. The national-level median period total fertility rate (TFR) is assumed to be 1.59 in 2025 then gradually decrease to 1.55 in 2054 and beyond. In 2024–2028 the medium fertility assumption ranges from 0.56 births per woman for Waitematā local board area, to 2.46 births for Ōpōtiki district. In 2049–2053 the assumed total fertility rate for Waitematā local board area remains the lowest at 0.56 births per woman, and Ōpōtiki district has the highest, but this decreases to 2.34 births per woman. A sex ratio at birth of 105.5 males per 100 females is assumed for each area, based on the historical annual average at the national level. Mortality The assumed mortality rates are based on the expected number of deaths for each area for the first five-year period (2024–2028), which is primarily based on death estimates in 2024–2025, with change between 2029 and 2053 consistent with the mortality assumptions from the National population projections: 2023(base)–2078. Under the median mortality assumption, period life expectancy at birth at the national level is assumed to increase from 80.8 years in 2025, to 85.2 years in 2053 for males (an increase of 4.4 years), and from 84.0 years in 2025, to 88.0 years in 2053 for females (an increase of 4.0 years). The assumed medium life expectancy at birth remains lowest in the Chatham Islands territory throughout the projection period, increasing from 74.9 years in 2024–2027 to 78.6 years in 2049–2053 for males (an increase of 3.7 years), and from 79.0 years to 81.6 years for females (an increase of 2.6 years). The assumed medium life expectancy at birth is highest in Queenstown-Lakes district through the projection period, increasing from 87.3 years in 2024–2027 to 90.4 for males in Queenstown-Lakes district in 2049–2053, an increase of 3.1 years. For females in Queenstown-Lakes district, assumed life expectancy at birth increases from 90.8 years to 92.9 years over the same period. This is an increase of 2.1 years of life for females over the projection period. 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, diet) changes in infectious diseases and resistance to antibiotics environmental change, disasters, and wars. Migration Migration at the subnational level has both an internal (to/from other areas of New Zealand) and an external (to/from overseas) component, although these separate components are difficult to quantify. The assumed net migration (combined internal and external) for each area is based on considerations of: Observed net migration during each intercensal period from 1996 to 2023 and estimates of annual net migration for 2024 and 2025 The capacity of an area for further growth (for areas with net inflow) Whether historical outflows can be sustained (for areas with net outflow) The desirability of the area to new migrants Information available from and about local authorities relating to current and future developments that may affect population change. Under the medium migration assumption, annual net migration at the national level is consistent with the national population projections median assumption of 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, and to 42,500 in the June 2051 year. However, the median assumption is not an assumed trajectory. It represents the median of the migration simulations, which vary every year around that median. The low and high net migration assumptions are chosen to represent plausible alternative migration scenarios for each area, so are not constrained to any national-level projections. The age-sex patterns of net migration for each area are based on observed intercensal net migration patterns during 1996–2023, see Estimated resident population (2023-base): At 30 June 2023 (since 2018), and the latest migration assumptions from the National population projections: 2024(base)–2078. en-NZ