How is the number of members in the House of Representatives determined?

The number of members of the House of Representatives is decided by rules set out in the Australian Constitution and the Electoral Act 1918.

Section 24 of the Constitution says the House of Representatives should be about twice the size of the Senate and that each member is chosen by and represents a quota – proportion – of the population. This quota is worked out by dividing the Australian population by twice the number of senators. The quota is then used to decide the number of members in the House for each state. This is done by dividing the population of the state by the quota.

The Constitution also guarantees that the states will have a minimum of 5 members in the House of Representatives regardless of population.

The formula for working out the number of members representing the Australian Capital Territory and the Northern Territory is outlined in the Electoral Amendment (Territory Representation) Act 2020. Under this Act, the two territories are each guaranteed at least one member in the House.

One year after a new Parliament first meets, the Australian Electoral Commission uses the latest population statistics to calculate how many members each state and territory is entitled to. States may gain or lose electorates if their population changes.