The rate of natural increase (RNI)—the difference between birth rates and death rates—plays a significant role in New Zealand's population growth. As of recent years, New Zealand’s RNI has been relatively modest, with a natural increase of around 0.6% per year, reflecting both declining birth rates and an aging population. In contrast, neighboring Australia has a slightly lower RNI, hovering around 0.4%, due to similar demographic trends but with a marginally older population. Meanwhile, Pacific Island nations such as Fiji and Samoa generally exhibit higher RNIs, often exceeding 1.0%, driven by higher fertility rates and younger populations. Thus, while New Zealand’s RNI is moderate compared to its immediate neighbors, it is considerably lower than many Pacific Island countries but somewhat higher than Australia, highlighting demographic transitions at different stages across the region.
| Year | Rate of Natural Increase | Population |
|---|---|---|
| 1990 | 0.985 | 3,413,677 |
| 1995 | 0.819 | 3,642,182 |
| 2000 | 0.788 | 3,802,400 |
| 2005 | 0.758 | 4,048,224 |
| 2010 | 0.831 | 4,269,245 |
| 2015 | 0.651 | 4,525,113 |
| 2020 | 0.589 | 4,925,334 |
| 2024 | 0.566 | 5,161,211 |
| 2025 | 0.547 | 5,207,259 |
| 2026 | 0.527 | 5,250,088 |
| 2030 | 0.437 | 5,412,025 |
| 2035 | 0.332 | 5,591,053 |
| 2040 | 0.245 | 5,746,399 |
| 2045 | 0.165 | 5,879,696 |
| 2050 | 0.09 | 5,990,813 |
| 2055 | 0.044 | 6,084,413 |
| 2060 | 0.007 | 6,165,734 |
| 2065 | -0.025 | 6,236,554 |
| 2070 | -0.059 | 6,297,435 |
| 2075 | -0.105 | 6,345,523 |
| 2080 | -0.162 | 6,376,941 |
| 2085 | -0.211 | 6,390,765 |
| 2090 | -0.238 | 6,392,377 |
| 2095 | -0.247 | 6,388,293 |
| 2100 | -0.259 | 6,381,409 |
Data from US Census International Database