Australia is 0.78 times as big as United States
Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. It is the largest country in Oceania and the world's sixth-largest country by total area. The population of 26 million is highly urbanised and heavily concentrated on the eastern seaboard.
The United States of America (USA), commonly known as the United States (U.S. or US) or America, is a country located primarily in North America, consisting of 50 states, a federal district, five major self-governing territories, and various possessions. At 3.8 million square miles (9.8 million square kilometers), it is the world's third- or fourth-largest country by total area.