User:Fanx/List of prime ministers of New Zealand by time in office

This is a list of Prime Ministers of New Zealand by time in office. The basis of the list is the difference between dates; as counted from midnight GMT. The first half day of a prime minister's term is counted in the total, but the last day is not. Prime ministers do not have a fixed term of office; instead, they may stay in office as long as their government is supported by parliament under a system of responsible government.

Historically, elections have been held every three years, however half of the 42 prime ministers have served fewer than three years. Richard Seddon had the longest tenure of any Prime Minister, serving over 13 years, while Henry Sewell, the shortest serving Prime Minister, spent 13 days in office.

Ranked list
The following list is ranked by their total term in office (multiple terms are added together to give the total term in office).

† - Died in office.

Note: Some lists consider Hugh Watt as a New Zealand Prime Minister. Watt served as acting Prime Minister for seven days from 31 August to 6 September 1972 following the death of Norman Kirk. He is not normally counted in the official numbering of New Zealand Prime Ministers.