If you’re visiting Australia you can use your drivers license from the United States to drive for, up to three months starting from the day you arrive. Just remember to have your license on you while driving. It should either be in English or accompanied by an accredited translation.
However if you plan on staying in Australia for than three months or if you become a resident you’ll need to get an Australian drivers license. The process may vary depending on which state or territory you’re. Generally involves passing a written test, a practical driving test and a vision test.
It’s important to note that Australians drive on the left hand side of the road so it might require some adjustment if you’re accustomed, to driving on the right hand side.