Template:2017 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 changes to electorate seats each party holds (ACT retains Epsom, Māori retains Waiariki, Labour retains Te Tai Tokerau, etc.) unless there is a specific reason to assume change. For example, after Peter Dunne announced his retirement, projections stopped assuming United Future would retain Ōhāriu. Other parties that do not pass the 5% threshold are assumed to not to win an electorate and therefore gain no seats.

Radio New Zealand takes a "poll of polls" average to produce their forecast. The New Zealand Herald bases theirs on a predictive model incorporating poll data as well as past election results and past poll accuracy. Newshub and 1 News and produce projections based on their own polls only.

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 they formed a 64-seat government with Māori, ACT and United Future.


 * * indicates an overhang seat