Australia is generally between 15 to 19 hours ahead of the US, depending on the specific time zones you're dealing with. For example, if you're on the east coast of the US, you'd be 16 hours behind Sydney, but only 12 hours behind Perth. The time difference can be confusing, but a simple trick is to use an online world clock or a time zone converter to figure out the exact difference. You can also use your phone's clock app to set up multiple time zones, which makes it easy to see the current time in different parts of the world, and schedule your call accordingly.