The flight distance from Seattle-Tacoma International Airport (SEA) in Seattle, United States to Sydney Kingsford Smith International Airport (SYD) in Sydney, Australia is 12,472 kilometers (7,750 miles / 6,734 nautical miles). The estimated flight time for this route is approximately 16h, flying west southwest at a heading of 243°.

This is an ultra-long-haul route, one of the longest in aviation. It requires wide-body aircraft with extended range capability such as the Airbus A350-900ULR or Boeing 777-200LR. Passengers should prepare for an extended flight with multiple meal services.

This is an international route connecting United States with Australia. It is an intercontinental flight between North America and Oceania. Travelers should check visa requirements, customs regulations, and any travel advisories before booking.

Time zone information: When it's 20:55 in Seattle, it's 15:55 in Sydney. With a 19-hour time difference, travelers should plan for significant jet lag. It typically takes one day per hour of time difference to fully adjust.

The return flight from Sydney (SYD) to Seattle (SEA) follows a heading of 47° (northeast). Actual flight times may vary depending on wind conditions, air traffic, and the specific aircraft used.

For more information about these airports, visit the Seattle-Tacoma International Airport (SEA) and Sydney Kingsford Smith International Airport (SYD) detail pages, or use our flight duration calculator to compare other routes.