Projected population change in Porirua City, New Zealand

Medium projection: Assuming medium fertility, medium mortality, and medium net migration.
High projection: Assuming high fertility, low mortality, and high net migration.
Low projection: Assuming low fertility, high mortality, and low net migration.

Natural increase: live births minus deaths
Net migration: Long-term arrivals to the area minus long-term departures from the area. This includes migration within New Zealand

The projections are not predictions. The projections are designed to meet both short-term and long-term planning needs, but are not designed to be exact forecasts or to project specific annual variation. These projections are based on assumptions made about future fertility, mortality, migration, and inter-ethnic mobility patterns of the population. Although the assumptions are carefully formulated to represent future trends, they are subject to uncertainty. Therefore, the projections and associated probability intervals should be used as guidelines and an indication of the overall trend, rather than as exact forecasts.

Data is displayed at the URL provided. Download unfiltered data in tabular text (CSV).

Subnational population projections indicate the future size and age-sex structure of the population of New Zealand's 16 regional council areas, 67 territorial authority areas, and 21 Auckland local board areas based on different combinations of fertility, mortality, and migration assumptions, and current policy settings.

These 2023-base subnational population projections supersede the updated 2018-base projections released in December 2022. The new projections incorporate the latest demographic information available including:
a. national population projections: 2024(base)–2078 (released 4 June 2025)
b. subnational population estimates
c. births and death registrations
d. international travel and migration data.
The new projections have the estimated resident population at 30 June 2023 as a base and cover the period to 2053 at five-year intervals.

Three alternative projections (designated low, medium, and high) have been produced for each area using different fertility, mortality, and migration assumptions. At the time of release, the medium projection is considered the most suitable for assessing future population change.
The low and high projections allow users to assess the impact on population size and structure resulting from lower growth and higher growth scenarios, respectively. The low projection uses low fertility, high mortality, and low net migration for each area. The high projection uses high fertility, low mortality, and high net migration for each area. The low and high projections are independent of the national population projections as they represent plausible alternative scenarios for each area.