The cheapest times to fly from STL to IAD are

  • August 6th to March 4th (except the weeks of November 19th, November 26th, December 10th, and December 24th)

based on data collected exclusively by Champion Traveler across tens of millions of flights. Among all the dates above, the very cheapest time to fly from STL to IAD is late October to early November. Prices can be as high as $729 for Sunday flights during mid May, or as low as $272 for Tuesday flights around late October to early November.


When to Fly to Washington

Flying from St. Louis, MO (STL) to Washington, DC (IAD) will usually cost between $286 to $470 per person if booking more than four weeks in advance. On average the very cheapest time to fly is late October to early November with an average ticket price of $293. Due to high demand the most expensive time to fly is mid May, with an average price of $445. Planning your trip to low-cost times can easily save you $152 on economy flights and even more on first-class flights. Generally, any price below $320 can be considered a good price for a round-trip STL to IAD flight.

See below for a graph of average weekly prices for the STL to IAD route. All prices are for round-trip tickets in USD.

STL to IAD Flight Prices

Compared to other flights, the STL to IAD flight is much cheaper than the average and costs much less than the average flight leaving from St. Louis. The average price per mile (for a direct flight) is $0.29, which is below average.


Flight Prices by Day of the Week

Tuesday is usually the cheapest day to depart and return on this flight. Sundays are the most expensive days to fly out or take a return trip. Selecting flights on the least expensive days could save you up to $83 (21%) on this flight.

Departing prices are for round-trip flights returning on the day of departure. For example, a flight departing on Tuesday and returning a week later will cost an average of $305. Return trip prices are from the IAD to STL flight, and often highlight the quality of our data in showing the same trend.

Departing Prices by Day

Departure Day Prices

Return Trip Prices by Day

Return Day Prices


Nonstop Flights and Layovers

Travelers looking to fly from STL to IAD can generally find a 0-layover flight. Because there is a direct flight option the real-world direct flight time of 2 hour 14 minutes may be realistic.


Alternative Nearby Airports

Champion Traveler tells you which airports are nearby and whether tickets might be cheaper alternative airports nearby. Sometimes it’s worth it to fly into a closer airport and then commute to your destination. Remember that there is a nonstop flight from STL to IAD while comparing.

Destination alternative #1: Charlottesville Albemarle Airport (CHO) in Charlottesville, VA

  • 77 miles (124 km) away from IAD
  • Usually 7.50% less expensive than IAD
  • 1-layover flights available

See STL to CHO flights

Destination alternative #2: University Park Airport (SCE) in State College, PA

  • 133 miles (214 km) away from IAD
  • Usually 6.88% less expensive than IAD
  • 1-layover flights available

See STL to SCE flights

Destination alternative #3: Ronald Reagan Washington National Airport (DCA) in Washington, DC

  • 24 miles (39 km) away from IAD
  • Usually 3.13% less expensive than IAD
  • Nonstop flights available

See STL to DCA flights


Flight Questions Answered

Still have questions about flying from STL to IAD? We’ve got answers.

Which airlines fly this route?

You can find 9 major airlines flying this route most often: Alaska, American, Cape Air, Delta, Frontier, Qantas, Southwest, Sun Country Airlines, United, and potentially more during busy seasons.

How far away is it from Washington Dulles International Airport to St Louis Lambert International Airport?

The distance between the two airports is roughly 694 miles or 1117 kilometers.

How long does it take to fly from STL to IAD?

The real-world flight time for a nonstop STL to IAD flight is about 2 hour 14 minutes.

How many flights go between St. Louis, MO and Washington, DC?

It depends on the day of the week and the date, but a typical day might have around 81 available flights from STL to IAD.


Airport Location Info


Departing Airport

Origination codeSTL
Origination airport nameSt Louis Lambert International Airport
CitySt. Louis, MO
Countrythe United States

Return Airport

Destination codeIAD
Destination airport nameWashington Dulles International Airport
CityWashington, DC
Countrythe United States


Other Resources

Please note that while we’ve worked hard to analyzed tens of millions of flights to get you this data, we do not calculate current live prices or guarantee pricing. Please see our partners using the links above for current offers.