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 Amendment (Territory Representation) Act 2020.

Section 24 of the Constitution says the House of Representatives should be about twice the size of the Senate. It also says that the number of members in the House of Representatives from each state will be based on the population of that state. This is worked out for each state using a formula:

1. Divide the total population of Australia by twice the number of state senators to get a quota.
2. Divide the population of the state by the quota.

This gives the number of representatives a state will be entitled to.

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

Unlike states, territories do not have a guaranteed minimum number of representatives under the Constitution. The rules for working out the number of members representing the territories are in the Electoral Amendment (Territory Representation) Act 2020. Under this law, the Australian Capital Territory and Northern Territory are each guaranteed at least one member in the House. A similar formula is used to work out how many representatives each territory is entitled to in the House.

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