Template:2023 NZ election forecasts

The use of mixed-member proportional representation allows ready conversion of a party's support into a party vote percentage and therefore a number of seats in Parliament. Projections generally assume no material change to the electorate seats held by each party (ACT retains Epsom, Greens retain Auckland Central, Māori retains Waiariki, etc.). Parties that do not hold an electorate seat and poll below 5% are assumed to win zero seats.

When determining the scenarios for the overall result, the minimum parties necessary to form majority governments are listed (provided parties have indicated openness to working together). Actual governments formed may include other parties beyond the minimum required for a majority; this happened after the 2014 election, when National only needed one seat from another party to reach a 61-seat majority, but instead chose to form a 64-seat government with Māori, ACT and United Future.

On 19 November 2022, New Zealand First leader Winston Peters ruled out a coalition with Labour, claiming "No one gets to lie to me twice". In April 2023, National leader Christopher Luxon commented that it would be "highly unlikely" that National would form a government with Te Pāti Māori or the Greens; however, a spokesperson later clarified Luxon had not "intended to fully rule out working" with either party. At the time, Te Pāti Māori was largely seen as the kingmaker in the upcoming election. Furthermore, Te Pāti Māori may not be prepared to support a National-led government that includes the ACT Party, as Te Pāti Māori has repeatedly accused the ACT Party of race baiting over co-governance and its calls for a referendum on the Treaty of Waitangi. On 10 May, Luxon officially ruled out forming a coalition with Te Pāti Māori. On 27 August, Labour leader Chris Hipkins ruled out New Zealand First as a possible coalition partner.