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New Zealand voters cast two votes: a party vote that largely determines each party’s total representation in Parliament, and an electorate vote that selects the local MP. Parties that qualify receive an overall seat entitlement calculated using the Sainte-Laguë formula; electorate winners fill seats first, then ranked party-list candidates fill any remaining places. If a party wins more electorates than its entitlement, it keeps those MPs and Parliament grows.

What the two votes decide

Vote What it chooses How it affects seats
Party vote The party a voter wants represented nationally It is the main factor determining the party’s overall number of MPs.
Electorate vote The candidate a voter wants to represent their local electorate It selects the electorate MP; the winner is the candidate with the most votes, even without a majority.

The Electoral Commission explains the distinction in its MMP overview and guide to voting. The party vote sets the broad balance between parties, while electorate votes determine who wins local contests.

How party votes become a party’s seat total

1. A party must qualify

A party qualifies for proportional seat allocation if it wins at least 5% of the nationwide party vote or wins at least one electorate. The electorate route is often called the “one-seat threshold,” but the Electoral Commission’s review describes it more precisely as a waiver of the party-vote threshold.

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2. Sainte-Laguë calculates the entitlement

For qualifying parties, the Sainte-Laguë formula converts party-vote totals into an overall number of seats. It is designed to make a party’s share of seats broadly reflect its share of party votes. As an illustration, the Electoral Commission says that 30% of party votes would correspond to about 36 of 120 seats, before any overhang effects. That example is not a guarantee that Parliament will contain exactly 120 MPs: overhangs can increase its size.

3. Electorate winners count toward that total

A party’s successful electorate candidates occupy its entitled seats first. The party then fills any remaining seats with candidates from its ranked list. For example, if a party’s entitlement is 36 seats and it has 20 electorate winners, those winners count toward the 36 and its list supplies the other 16, assuming no overhang.

What happens when a party wins an electorate but gets under 5%?

Winning at least one electorate lets a party qualify even if it receives less than 5% of the party vote. Its party-vote share is then used in the seat-allocation process alongside other qualifying parties; the electorate win is not simply an extra seat on top of its entitlement unless the party wins more electorates than that entitlement.

The Electoral Commission’s 2012 review illustrates the rule with 2008 results: the Greens received 6.7% of party votes and nine seats; ACT received 3.6% but qualified through an electorate win and obtained five seats; New Zealand First received 4.1%, won no electorate and received no seats. These are historical examples from the 2008 election, not current outcomes.

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When an overhang makes Parliament larger

An overhang occurs if a party wins more electorates than its party-vote-based seat entitlement. The party keeps all its electorate MPs rather than removing a local winner to match the entitlement, so Parliament expands by the excess seat or seats. The Electoral Commission reports that five Parliaments have had overhangs and that the Parliament following the 2023 General Election has 123 MPs. The 123 figure refers to that Parliament and may change after later elections.

Why the qualification threshold matters

The threshold is a trade-off between proportional representation and limiting the number of very small parties in Parliament. In its 2012 review, the Electoral Commission noted that a higher threshold can make representation less proportional, while a lower one may make parliamentary effectiveness and government stability harder to secure. The electorate-win route allows a party with local support to qualify even when its national party-vote share is below 5%.

Try a hypothetical result

The Electoral Commission’s MMP seat-allocation calculator, updated in September 2026, accepts party-vote totals or percentages and assumptions about electorate seats. It can help illustrate how changing either input affects party entitlements and possible overhangs; it is a calculator for exploring scenarios, not a forecast of an election result.

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How New Zealand adopted MMP

After a Royal Commission recommended MMP, New Zealand held an indicative referendum in 1992 and a binding referendum in 1993. The Electoral Commission’s account records that 70.5% chose MMP in the 1992 vote and 53.9% voted for change from First Past the Post in the 1993 referendum. These are results of the historical referendums, not measures of current public opinion.

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Sources: Electoral Commission: What is MMP?; Electoral Commission: Your vote; Electoral Commission: MMP seat-allocation calculator; Electoral Commission: 2012 MMP review; Electoral Commission: MMP history.

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