Flight time from St. Louis Mo to Sydney Australia?

The flight time from St. Louis, Missouri (STL) to Sydney, Australia (SYD) is approximately 17 hours and 30 minutes on a direct flight. However, due to the distance and the winds, the actual flight time can vary. It's important to note that there are no direct flights from St. Louis to Sydney, so passengers will likely have to connect through another city, such as Los Angeles (LAX) or San Francisco (SFO), adding additional time to the journey.