The flight distance from St Louis Lambert International Airport (STL) in St Louis, United States to Mehrabad International Airport (THR) in Tehran, Iran is 10,850 kilometers (6,742 miles / 5,858 nautical miles). The estimated flight time for this route is approximately 14h, flying north northeast at a heading of 31°.

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 Iran. It is an intercontinental flight between North America and Asia. Travelers should check visa requirements, customs regulations, and any travel advisories before booking.

Time zone information: When it's 18:27 in St Louis, it's 03:57 in Tehran. With a 9.5-hour time difference, travelers should plan for significant jet lag. It typically takes one day per hour of time difference to fully adjust.

There is a significant elevation difference of 3,345 feet between the two airports. Mehrabad International Airport sits higher than St Louis Lambert International Airport.

The return flight from Tehran (THR) to St Louis (STL) follows a heading of 331° (north northwest). Actual flight times may vary depending on wind conditions, air traffic, and the specific aircraft used.

For more information about these airports, visit the St Louis Lambert International Airport (STL) and Mehrabad International Airport (THR) detail pages, or use our flight duration calculator to compare other routes.