Parliament usually has 120 MPs. Of these 120 MPs, 72 of these are electorate MPs which represent local communities around New Zealand. The remainder of around 48 MPs are list MPs. Before each election each party creates a ranked list of candidates which become list MPs. List MPs help ensure Parliament matches the nationwide Party Vote. 

For example, if a party earns enough votes for 30 MPs and they win 18 electorate seats, they will receive 12 list MPs to make up for the total 30 MP seats earned. 

​

Although Parliament usually has 120 MPs the number of seats can increase based on the MMP voting system. Currently Parliament is made up of 123 MPs. 

There are 3 more MPs in Parliament than usual as during the 2023 election Te Pati Māori won 6 electorate seats and only about 3% of the nationwide party vote. Based on the nationwide party vote Te Pati Māori was entitled to 4 MP seats in Parliament, however under the MMP voting system a party never loses electorate seats that they've won. So instead of reducing Te Pati Māori seats to 4, Parliament increased its number of seats from 120 to 122. 

Another reason Parliament seats increased in the 2023 election, is because a candidate standing in an electorate died after nominations closed but before election day. Under New Zealand law the electorate election in the region had to be postponed until after the general election day. Parliament had to be formed immediately, so an extra list MP was temporarily added to keep Parliament at its minimum size. Weeks later the electorate vote took place, and the MP was added to Parliament without removing the list MP, therefore increasing the number of MP seats from 122 to 123. 

​