Explained: One North Island electorate will disappear before the next election – here’s why

Stats NZ has confirmed one electoral seat will be removed in the North Island for the 2026 general election.

There will be one less electorate at the next general election in 2026 than there is today.

The seat will be removed from the North Island, which will reduce the total from 49 to 48 electorates.

Stats NZ has confirmed the electorate boundaries in the North Island will be redrawn, but which seat will be lost is not yet known.

But how can that be if the population is increasing, you ask?

Here’s why it’s happening.

In the South Island, the number of electorate seats is always, by law, fixed at 16, while the number of electorate seats in the North Island depends on the size of the population as recorded in the Census.

The North Island will lose one electorate seat because the South Island population grew faster than the North Island population.

The general electoral population of the North Island is 3,353,982, up 5.5% from the last Census in 2018. For the South Island it is 1,120,593, up 7% from 2018.

How does it work?

The law requires each electorate in the country to be of a similar size. This is achieved via a two-step process.

The first step, announced yesterday, is to determine the number of electorates and the ideal electorate size. The second step is to adjust the boundaries to try to ensure all electorates are within 5% of the ideal size.

The process starts in the South Island.

Officials calculate the target electorate size by taking the electoral population of the South Island (1,120,593) and dividing it by 16 (the legislated number of seats) to get the “quota” or size of each electorate in the South Island.

The current quota for each seat in the South Island is 70,037.

Then, officials take the North Island electoral population (3,353,982) and divide it by the South Island quota (70,037) to determine the number of electorates there will be in the North Island (48 – down from 49 during the past two elections).

North Island electoral population (3,353,982) ÷ South Island quota (70,037) = 48

The quota for North Island general electorates is 69,875 people (3,353,982 ÷ 48) and it differs from the South Island figure because there must be a round number of electorates.

One North Island electorate will be removed and the boundaries of the remaining electorates will be moved so the general electoral population of every electorate falls between 66,381 and 73,369.

The number of Māori electorates will remain at seven. For Māori electorates, the quota is 74,367 people.

One of the Māori electorates – Ikaroa-Rāwhiti – will also have its boundaries redrawn because its electoral population currently sits outside the 5% tolerance.

Given New Zealand has 120 parliamentary seats (excluding overhang), this now means there will be one more list seat.

In total, there will be 71 electorate seats and 49 list seats.

Julia Gabel is a Wellington-based political reporter. She joined the Herald in 2020 and has most recently focused on data journalism.