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Dulles Intl

$64+ 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 7/6. Fares are subject to change and may not be available on all flights or dates of travel.
STL — IAD
6月 19 — 6月 261
週五 6/19
週五 6/26
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 February or September, booked 15 days in advance, depart on a Tuesday or Wednesday and return on a Saturday

Cheap 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 5月 20, 2026.

This Frontier deal was found by Cheapflights users on 5/18. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
週三 7/294:52 pm
STL
-
IAD
1 stop5h 21m
Frontier
週六 8/11:23 pm
IAD
-
STL
1 stop11h 36m
Frontier
Deal found 5/18$244
This Orbitz deal was found by Cheapflights users on 5/15. 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 Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
週三 6/175:06 pm
STL
-
IAD
1 stop5h 11m
Frontier
週四 6/187:30 am
IAD
-
STL
1 stop11h 00m
Frontier
Deal found 5/15$249
This Kiwi.com deal was found by Cheapflights users on 5/16. 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.
週六 8/154:52 pm
STL
-
IAD
1 stop5h 21m
Multiple Airlines
週一 8/172:52 pm
IAD
-
STL
2 stops10h 07m
Multiple Airlines
Deal found 5/16$250
This Expedia deal was found by Cheapflights users on 5/16. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
週四 6/252:56 pm
STL
-
IAD
1 stop16h 29m
Frontier
週一 6/291:38 pm
IAD
-
STL
1 stop11h 11m
Frontier
Deal found 5/16$254
This Kiwi.com deal was found by Cheapflights users on 5/17. 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.
週日 6/76:33 pm
STL
-
IAD
2 stops24h 17m
Frontier
週日 6/147:30 am
IAD
-
STL
1 stop26h 22m
Frontier
Deal found 5/17$260
This Kiwi.com deal was found by Cheapflights users on 5/18. 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.
週五 6/265:06 pm
STL
-
IAD
1 stop5h 16m
Frontier
週一 6/298:57 pm
IAD
-
STL
1 stop21h 33m
Frontier
Deal found 5/18$261
This Expedia deal was found by Cheapflights users on 5/19. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
週五 6/124:17 pm
STL
-
IAD
1 stop19h 11m
Frontier
週二 6/1611:24 am
IAD
-
STL
1 stop7h 06m
Frontier
Deal found 5/19$262
This Frontier deal was found by Cheapflights users on 5/18. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
週六 6/205:06 pm
STL
-
IAD
1 stop5h 11m
Frontier
週二 6/2311:24 am
IAD
-
STL
1 stop7h 06m
Frontier
Deal found 5/18$263
This Kiwi.com deal was found by Cheapflights users on 5/19. 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.
週一 6/88:08 pm
STL
-
IAD
2 stops13h 14m
Frontier
週三 6/108:57 pm
IAD
-
STL
1 stop21h 33m
Frontier
Deal found 5/19$265
This Kiwi.com deal was found by Cheapflights users on 5/19. 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.
週四 7/96:33 pm
STL
-
IAD
1 stop14h 40m
Frontier
週日 7/128:57 pm
IAD
-
STL
1 stop13h 00m
Frontier
Deal found 5/19$266
This United Airlines deal was found by Cheapflights users on 5/17. 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.
週二 6/3012:55 pm
STL
-
IAD
Nonstop2h 12m
United Airlines
週二 7/145:42 pm
IAD
-
STL
1 stop4h 44m
United Airlines
Deal found 5/17$267

Find 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 5月 20, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$244
(Frontier)

One-way from

$64
(Kiwi.com)

Popular in

July

Cheapest in

February

Average price

$325

Good round-trip deal

$516 or less

Good one-way deal

$350 or less
Provider with most accurate pricing for Lambert-St Louis-Washington, D.C. Dulles Intl flight deals.
Search Deals
Provider most trusted by Cheapflights users for Lambert-St Louis-Washington, D.C. Dulles Intl flights.
Search Deals
From Lambert-St Louis to Washington, D.C. Dulles Intl
Search Deals
One-way flight from Lambert-St Louis to Washington, D.C. Dulles Intl
Search Deals
Highest demand for flights based on searches. 13% potential increase in price ($56 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($12 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in May 2026
Search Deals
Price to beat on a round-trip flight from Lambert-St Louis to Washington, D.C. Dulles Intl.
Search Deals
Price to beat on a one-way flight from Lambert-St Louis to Washington, D.C. Dulles Intl.
Search Deals

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 5月 20, 2026.
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

Fly to

Route

Depart

Return

Price

Cheapest round-trip

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

週一 6/15

6:10 pm-11:14 pm

1 stop4h 04m

Washington, D.C. Dulles Intl

週二 6/23

6:00 am-9:46 am

1 stop4h 46m

$306

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

週一 6/29

6:13 pm-12:13 am

1 stop5h 00m

Washington, D.C. Dulles Intl

週三 7/1

8:22 pm-11:44 pm

1 stop4h 22m

$331

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

週四 6/25

1:39 pm-9:04 pm

1 stop6h 25m

Washington, D.C. Dulles Intl

週日 7/12

6:00 am-9:31 am

1 stop4h 31m

$358

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

週三 7/29

8:43 am-11:55 am

Nonstop2h 12m

Washington, D.C. Dulles Intl

週六 8/1

5:42 pm-9:26 pm

1 stop4h 44m

$372

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

週五 7/31

6:58 pm-12:41 am

1 stop4h 43m

Washington, D.C. Dulles Intl

週日 8/2

6:00 am-9:31 am

1 stop4h 31m

$379

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

週一 6/29

8:43 am-11:55 am

Nonstop2h 12m

Washington, D.C. Dulles Intl

週三 7/1

8:15 am-12:11 pm

1 stop4h 56m

$384

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

週五 6/19

7:12 pm-12:44 am

1 stop4h 32m

Washington, D.C. Dulles Intl

週日 6/21

6:05 am-9:32 am

1 stop4h 27m

$390

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

週六 6/6

12:55 pm-4:07 pm

Nonstop2h 12m

Washington, D.C. Dulles Intl

週四 6/11

10:31 am-3:46 pm

1 stop6h 15m

$402

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

週四 6/11

7:12 pm-12:44 am

1 stop4h 32m

Washington, D.C. Dulles Intl

週四 6/18

6:05 am-9:32 am

1 stop4h 27m

$407

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

週二 6/9

8:43 am-11:55 am

Nonstop2h 12m

Washington, D.C. Dulles Intl

週五 6/12

5:42 pm-11:35 pm

1 stop6h 53m

$420

Flights are sorted by cheapest round-trip flights first.

Deals found on 5/18

Showing 1-10 of 21 resultsSorted by cheapest first
1
2
3

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 May.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy1 starTrust Score*3 stars
FlightHubPrice 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?

The best time to book flights from St. Louis to Washington, D.C. Dulles Intl Airport is 14 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, February is the cheapest month in which you can book a flight from St. Louis to Washington, D.C. Dulles Intl Airport (average of $170). Flying from St. Louis to Washington, D.C. Dulles Intl Airport in July is currently the most expensive (average of $489). 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 5月 20, 2026.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from St. Louis to Washington, D.C. Dulles Intl Airport as you normally would.

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

AI-powered summary based on content written by travel experts. AI can make mistakes.
Cheapflights partnered with top experts to bring you the best recommendations for your St. Louis to Washington, D.C. Dulles Intl Airport trip
Our travel experts
Taryn White

Taryn White

Expert on STL

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

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 5月 20, 2026.
Peruse reviews from past customers who have flown with Delta,United Airlines, andAmerican 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
8,452 reviews

Crew

8.5

Overall

7.9

Comfort

7.8

Entertainment

7.8

Boarding

8.1

Food

7.2

Reviews

1 / 20
10.0
Excellent

Anonymous,May 2026

SEA - KOA

The snacks were not very good, not everyone was very friendly and professional
Delta
7.9
Good
8,452 reviews
Delta
7.9
Good
8,452 reviews

Crew

8.5

Overall

7.9

Comfort

7.8

Entertainment

7.8

Boarding

8.1

Food

7.2

Reviews

1 / 20
10.0
Excellent

Anonymous,May 2026

SEA - KOA

The snacks were not very good, not everyone was very friendly and professional
United Airlines
7.4
Good
9,738 reviews
Delta
7.9
Good
8,452 reviews

Crew

8.5

Overall

7.9

Comfort

7.8

Entertainment

7.8

Boarding

8.1

Food

7.2

Reviews

1 / 20
10.0
Excellent

Anonymous,May 2026

SEA - KOA

The snacks were not very good, not everyone was very friendly and professional
American Airlines
7.1
Good
11,642 reviews
Delta
7.9
Good
8,452 reviews

Crew

8.5

Overall

7.9

Comfort

7.8

Entertainment

7.8

Boarding

8.1

Food

7.2

Reviews

1 / 20
10.0
Excellent

Anonymous,May 2026

SEA - KOA

The snacks were not very good, not everyone was very friendly and professional
Frontier
5.7
Fair
2,945 reviews
Delta
7.9
Good
8,452 reviews

Crew

8.5

Overall

7.9

Comfort

7.8

Entertainment

7.8

Boarding

8.1

Food

7.2

Reviews

1 / 20
10.0
Excellent

Anonymous,May 2026

SEA - KOA

The snacks were not very good, not everyone was very friendly and professional

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 3 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 2h 12m. Delta provides one of the quickest options available for as low as $372. 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 $90, 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 American Airlines - these airlines can fly you to your destination from $141 and $257, respectively. Frontier is 74% cheaper than the average price of flights available within the next 90 days to this destination.

  • What are the cheapest airlines to fly from St. Louis to Washington, D.C. Dulles Intl Airport one-way?

    To fly one-way, consider booking your trip with Frontier, which is currently one of the cheapest options available, starting at $72. Delta flights start at $99 while deals on American Airlines start at $128 one-way.

  • 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 United Airlines (86%), Avianca (85%) or GoJet (79%) 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 $814 for a flight from St. Louis to Washington, D.C. Dulles Intl Airport. The cheapest flight overall is $334 while the most popular route, (Lambert-St Louis - Washington, D.C. Dulles Intl) is currently priced at $257.

  • 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, February is the cheapest month in which you can book a flight from St. Louis to Washington, D.C. Dulles Intl Airport (average of $170). Flying from St. Louis to Washington, D.C. Dulles Intl Airport in July is currently the most expensive (average of $489). 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
Tysons
Owings Mills
Springfield
Arlington
Herndon
Rockville
Hyattsville
Manassas
Fredericksburg
Hanover
Chantilly
Laurel
Falls Church
Waldorf
Silver Spring
Largo
Clinton
Reston
Hunt Valley

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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 5月 20, 2026.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$90Average$184FlexibilityNo cancel feeOn-time62%
DeltaCheapest$141Average$290FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$257Average$323FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$271Average$456FlexibilityNo cancel feeOn-time69%

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