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Dulles Intl

$53+ Cheap flights from St. Louis (STL) to Dulles Intl (IAD)

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 12/25. Fares are subject to change and may not be available on all flights or dates of travel.
STL — IAD
Nov 22 — Nov 291
Sat 11/22
Sat 11/29
1 adult, Economy
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Cheapflights Tip: The best prices from Lambert-St Louis to Washington, D.C. Dulles Intl are usually found in March or January, booked 31 days in advance, depart on a Friday or Tuesday and return on a Wednesday

Cheap flight deals from St. Louis to Dulles Intl

Discover tips and strategies to find the most affordable flight options for your journey from St. Louis (STL) to Dulles Intl (IAD). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated October 23, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$202
(Kiwi.com)

One-way from

$53
(Trip.com)

Popular in

July

Cheapest in

March

Average price

$409

Good round-trip deal

$473 or less

Good one-way deal

$298 or less
Provider with most accurate pricing for Lambert-St Louis-Washington, D.C. Dulles Intl flight deals.
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Provider most trusted by Cheapflights users for Lambert-St Louis-Washington, D.C. Dulles Intl flights.
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From Lambert-St Louis to Washington, D.C. Dulles Intl
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One-way flight from Lambert-St Louis to Washington, D.C. Dulles Intl
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Highest demand for flights based on searches. 4% potential increase in price ($19 potential increase over avg. RT price).
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Cheapest flight prices on average. 3% potential price decrease ($11 potential savings vs. average RT price).
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Average for round-trip flights in October 2025
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Price to beat on a round-trip flight from Lambert-St Louis to Washington, D.C. Dulles Intl.
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Price to beat on a one-way flight from Lambert-St Louis to Washington, D.C. Dulles Intl.
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Find flight deals from St. Louis to Dulles Intl

Cheapest flights from St. Louis to Dulles Intl
Explore the most affordable flight options available from St. Louis to Dulles Intl. Find the lowest fares from popular airlines and budget airlines, with prices last updated on October 23, 2025.

This Mytrip deal was found by Cheapflights users on 10/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/314:52 pmSTL - IAD
1 stop5h 37mFrontier
Sat 11/18:36 pmIAD - STL
1 stop18h 41mFrontier
Deal found 10/23$202
This Kiwi.com deal was found by Cheapflights users on 10/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/137:43 pmSTL - IAD
2 stops14h 26mFrontier
Sat 1/103:33 pmIAD - STL
1 stop8h 00mFrontier
Deal found 10/23$214
This Kiwi.com deal was found by Cheapflights users on 10/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/67:43 pmSTL - IAD
2 stops14h 26mFrontier
Sat 12/135:45 amIAD - STL
1 stop29h 02mFrontier
Deal found 10/22$217
This Kiwi.com deal was found by Cheapflights users on 10/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/1311:07 amSTL - IAD
1 stop12h 04mFrontier
Sun 11/166:00 amIAD - STL
2 stops28h 07mFrontier
Deal found 10/21$223
This Kiwi.com deal was found by Cheapflights users on 10/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/173:30 pmSTL - IAD
2 stops19h 08mFrontier
Sat 1/103:33 pmIAD - STL
1 stop8h 00mFrontier
Deal found 10/21$229
This Kiwi.com deal was found by Cheapflights users on 10/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 11/47:45 pmSTL - IAD
2 stops23h 35mFrontier
Wed 11/198:40 amIAD - STL
1 stop15h 21mFrontier
Deal found 10/22$231
This Kiwi.com deal was found by Cheapflights users on 10/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/74:56 pmSTL - IAD
1 stop6h 15mFrontier
Tue 11/118:40 amIAD - STL
2 stops25h 27mFrontier
Deal found 10/22$232
This Kiwi.com deal was found by Cheapflights users on 10/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/1210:42 amSTL - IAD
2 stops8h 42mFrontier
Sat 1/103:33 pmIAD - STL
1 stop8h 00mFrontier
Deal found 10/23$238
This Kiwi.com deal was found by Cheapflights users on 10/20. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/77:45 pmSTL - IAD
2 stops23h 06mFrontier
Sun 11/96:00 amIAD - STL
1 stop5h 12mFrontier
Deal found 10/20$239
This United Airlines deal was found by Cheapflights users on 10/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/126:42 pmSTL - IAD
1 stop4h 13mUnited Airlines
Sun 12/148:40 amIAD - STL
Nonstop2h 27mUnited Airlines
Deal found 10/22$240
This Kiwi.com deal was found by Cheapflights users on 10/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/611:07 amSTL - IAD
1 stop12h 04mFrontier
Mon 11/105:44 pmIAD - STL
2 stops40h 23mFrontier
Deal found 10/22$242

Cheapflights Fare Finder

 
Customize your flight search to find flights from St. Louis to Dulles Intl that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated October 23, 2025.
Use the filters below to find and compare flights from St. Louis to Washington, D.C. Dulles Intl Airport that are best for you.

Fly from

St. Louis

Fly to

Dulles Intl

Route

Depart

Return

Price

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 12/23

6:35 pm-12:15 am

1 stop4h 40m

Washington, D.C. Dulles Intl

Thu 1/1

8:35 am-10:08 am

Nonstop2h 33m

$245

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 2/13

7:41 am-4:03 pm

1 stop7h 22m

Washington, D.C. Dulles Intl

Tue 2/17

5:17 pm-9:00 pm

1 stop4h 43m

$258

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Wed 11/19

8:25 am-11:33 am

Nonstop2h 08m

Washington, D.C. Dulles Intl

Mon 11/24

8:30 am-2:24 pm

1 stop6h 54m

$261

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Wed 11/19

11:39 am-6:26 pm

1 stop5h 47m

Washington, D.C. Dulles Intl

Mon 11/24

7:01 am-1:00 pm

1 stop6h 59m

$271

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Wed 11/19

8:25 am-11:33 am

Nonstop2h 08m

Washington, D.C. Dulles Intl

Tue 12/2

6:30 am-12:15 pm

1 stop6h 45m

$273

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 11/11

1:55 pm-9:32 pm

1 stop6h 37m

Washington, D.C. Dulles Intl

Tue 11/18

5:03 pm-8:46 pm

1 stop4h 43m

$283

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 12/9

8:30 am-11:40 am

Nonstop2h 10m

Washington, D.C. Dulles Intl

Mon 1/12

5:38 pm-11:59 pm

1 stop7h 21m

$285

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 12/11

11:25 am-5:30 pm

1 stop5h 05m

Washington, D.C. Dulles Intl

Tue 1/13

5:38 pm-11:59 pm

1 stop7h 21m

$288

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Wed 12/17

8:30 am-11:40 am

Nonstop2h 10m

Washington, D.C. Dulles Intl

Sun 1/11

8:20 am-2:30 pm

1 stop7h 10m

$291

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sat 2/21

8:30 am-11:40 am

Nonstop2h 10m

Washington, D.C. Dulles Intl

Wed 2/25

8:40 am-10:13 am

Nonstop2h 33m

$291

Flights are sorted by cheapest round-trip flights first.

Deals found on 10/23

Showing 1-10 of 21 results
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Compare providers for flights from St. Louis to Dulles Intl

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from St. Louis to Dulles Intl in October.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy2 starsTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*3 stars
eDreamsPrice Accuracy3 starsTrust Score*3 stars
PricelinePrice Accuracy1 starTrust Score*3 stars

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on St. Louis-Washington, D.C. Dulles Intl Airport flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on St. Louis-Washington, D.C. Dulles Intl Airport flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from St. Louis-Washington, D.C. Dulles Intl Airport flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on St. Louis-Washington, D.C. Dulles Intl Airport flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for St. Louis-Washington, D.C. Dulles Intl Airport flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

Best time to book a flight from St. Louis to Dulles Intl

Have a flexible travel schedule? Discover the best time to fly to Dulles Intl from St. Louis with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from St. Louis to Washington, D.C. Dulles Intl Airport

How far ahead should I book a flight from St. Louis to Washington, D.C. Dulles Intl Airport?

Use this chart to determine the optimal time to book a round-trip flight from St. Louis to Dulles Intl. Price data was last updated on October 17, 2025.

The best time to book flights from St. Louis to Washington, D.C. Dulles Intl Airport is 31 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.

What is the cheapest month to book a flight from St. Louis to Washington, D.C. Dulles Intl Airport?

Currently, December is the cheapest month in which you can book a flight from St. Louis to Washington, D.C. Dulles Intl Airport (average of $98). Flying from St. Louis to Washington, D.C. Dulles Intl Airport in March is currently the most expensive (average of $261). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from STL to IAD?

Find hourly flight availability from St. Louis to Dulles Intl. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated October 23, 2025.

It’s optimal to fly from St. Louis to Washington, D.C. Dulles Intl Airport in the evening. By choosing this option you can save up to 77% on the cost of your flight, compared to a flight at noon.

How much does it cost to fly round-trip from St. Louis to Washington, D.C. Dulles Intl Airport?

The best insider tips for St. Louis to Washington, D.C. Dulles Intl Airport flights

Snippets provided in this section are AI-generated based on a summarization of Cheapflights-commissioned articles. The articles are presented as-is, for general informational purposes only, and may not be up-to-date. The opinions contained in the articles are original to the author and reflect their authentic experience, which may vary significantly from the experience of others.
Cheapflights partnered with top experts to bring you the best recommendations for your St. Louis to Washington, D.C. Dulles Intl Airport trip
Airports
STL

Expect security screening at STL to take 5-10 minutes during off-peak times. Check real-time wait times online before heading to the airport.

Read more about STLby Taryn White
IAD

The Washington Metro Silver Line reaches IAD in under 40 minutes, offering a cheap and convenient way to get to the airport.

Read more about IADby Ramsey Qubein
Our travel experts
Taryn White

Taryn White

Expert on STL

Taryn White

Taryn White

Taryn White is a freelance travel writer, digital creator, and travel advisor who has visited nearly 100 countries and all 50 states. She’s familiar with many airports and enjoys beach hopping, boutique hotels, spa experiences, and exploring local culture. Her work has appeared in Travel + Leisure, Condé Nast Traveler, National Geographic, Smithsonian Magazine, AFAR, and more.

Read more
Ramsey Qubein

Ramsey Qubein

Expert on IAD

Ramsey Qubein

Ramsey Qubein

An avid traveler and aviation expert who has visited 173 countries, all 50 states and seven continents, Ramsey Qubein flies nearly 400,000 miles a year. As a North Carolina-based freelance journalist for publications including Conde Nast Traveler, Forbes, USA Today and Bloomberg among others, he explores the latest trends in aviation, hospitality, cruises and business.

Read more

Reviews of airlines servicing Dulles Intl

Get insights into the airlines that provide service to Dulles Intl. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Dulles Intl. Reviews last updated October 23, 2025.
Peruse reviews from past customers who have flown with Delta, United Airlines, and American Airlines from St. Louis to Washington, D.C. Dulles Intl Airport to help guide your decision. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Delta
7.9
Good
7,982 reviews

Boarding

8.2

Overall

7.9

Entertainment

7.9

Crew

8.5

Comfort

7.9

Food

7.3

Reviews

1 / 20
8.0
Excellent

Matthew,Oct 2025

GSP - ATL

This is always a full flight since it is the connecting route to primary destinations through Atlanta. That said, the crew handles the full load well. Not much more to say, it is a short flight with no in-flight services due to the length.
Delta
7.9
Good
7,982 reviews
Delta
7.9
Good
7,982 reviews

Boarding

8.2

Overall

7.9

Entertainment

7.9

Crew

8.5

Comfort

7.9

Food

7.3

Reviews

1 / 20
8.0
Excellent

Matthew,Oct 2025

GSP - ATL

This is always a full flight since it is the connecting route to primary destinations through Atlanta. That said, the crew handles the full load well. Not much more to say, it is a short flight with no in-flight services due to the length.
United Airlines
7.4
Good
8,995 reviews
Delta
7.9
Good
7,982 reviews

Boarding

8.2

Overall

7.9

Entertainment

7.9

Crew

8.5

Comfort

7.9

Food

7.3

Reviews

1 / 20
8.0
Excellent

Matthew,Oct 2025

GSP - ATL

This is always a full flight since it is the connecting route to primary destinations through Atlanta. That said, the crew handles the full load well. Not much more to say, it is a short flight with no in-flight services due to the length.
American Airlines
7.2
Good
11,033 reviews
Delta
7.9
Good
7,982 reviews

Boarding

8.2

Overall

7.9

Entertainment

7.9

Crew

8.5

Comfort

7.9

Food

7.3

Reviews

1 / 20
8.0
Excellent

Matthew,Oct 2025

GSP - ATL

This is always a full flight since it is the connecting route to primary destinations through Atlanta. That said, the crew handles the full load well. Not much more to say, it is a short flight with no in-flight services due to the length.
Frontier
5.8
Fair
3,128 reviews
Delta
7.9
Good
7,982 reviews

Boarding

8.2

Overall

7.9

Entertainment

7.9

Crew

8.5

Comfort

7.9

Food

7.3

Reviews

1 / 20
8.0
Excellent

Matthew,Oct 2025

GSP - ATL

This is always a full flight since it is the connecting route to primary destinations through Atlanta. That said, the crew handles the full load well. Not much more to say, it is a short flight with no in-flight services due to the length.

Related info for your journey

Find useful and relevant information for your journey from St. Louis to Dulles Intl. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly from for flights from St. Louis to Washington, D.C. Dulles Intl?

    Most people fly from Lambert-St Louis (STL) if they book a flight from St. Louis to Washington, D.C. Dulles Intl. On average, Lambert-St Louis has 4 outbound flights to Washington, D.C. Dulles Intl per day from 4 airlines. Lambert-St Louis is conveniently located just 12.7 mi from St. Louis’s city center.

  • How long is the flight from St. Louis to Washington, D.C. Dulles Intl Airport?

    A quick flight from St. Louis to Washington, D.C. Dulles Intl Airport can take about 4h 40m. United Airlines provides one of the quickest options available for as low as $245. There are 694 mi between St. Louis and Washington, D.C. Dulles Intl Airport. When browsing for deals, the options you’ll see will be for both nonstop flights and flights with stops.

  • What are the cheapest airlines flying from St. Louis to Washington, D.C. Dulles Intl Airport round-trip?

    Currently priced at $111, Frontier will fly you from St. Louis to Washington, D.C. Dulles Intl Airport and back. In addition to Frontier, many other airlines offer competitively priced options for your trip. Search Cheapflights for deals from Delta and United Airlines - these airlines can fly you to your destination from $124 and $233, respectively. Frontier is 70% cheaper than the average price of flights available within the next 90 days to this destination.

  • What are the most reliable airlines from St. Louis to Washington, D.C. Dulles Intl Airport?

    No one likes to see their flight delayed. When booking a flight from St. Louis to Washington, D.C. Dulles Intl Airport consider choosing Copa Airlines (85%), Avianca (85%) or Lufthansa (80%) as they are the most reliable in getting you off to your destination on time.

  • What are the cheapest flights from St. Louis to Washington, D.C. Dulles Intl Airport?

    On average you can expect to pay $894 for a flight from St. Louis to Washington, D.C. Dulles Intl Airport. The cheapest flight overall is $198 while the most popular route, (Lambert-St Louis - Washington, D.C. Dulles Intl) is currently priced at $174.

  • Can I find deals for flights from St. Louis to Dulles Intl that include hotel bookings?

    Yes. In addition to deals on St. Louis to Dulles Intl flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from St. Louis to Dulles Intl?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from St. Louis to Dulles Intl.

  • Can I find deals for business class flights from St. Louis to Dulles Intl?

    Yes. Cheapflights offers flight deals from St. Louis to Dulles Intl by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from St. Louis to Washington, D.C. Dulles Intl Airport?

    Currently, December is the cheapest month in which you can book a flight from St. Louis to Washington, D.C. Dulles Intl Airport (average of $98). Flying from St. Louis to Washington, D.C. Dulles Intl Airport in March is currently the most expensive (average of $261). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Traveling to a place near Washington, D.C. Dulles Intl Airport?

Book flights to Washington, D.C. Dulles Intl Airport if you plan to visit one of these locations
Alexandria
Woodbridge
Tysons
Arlington
Springfield
Silver Spring
Hanover
Gaithersburg
Fredericksburg
Fairfax
Linthicum Heights
Falls Church
Owings Mills
Manassas
Largo
Oxon Hill
Laurel
Towson
National Harbor
Waldorf

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Top 4 airlines flying from St. Louis to Dulles Intl

Discover the top 4 airlines that operate flights from St. Louis to Dulles Intl. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated October 23, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$111Average$184FlexibilityNo cancel feeOn-time62%
DeltaCheapest$124Average$271FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$233Average$423FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$250Average$341FlexibilityNo cancel feeOn-time71%

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