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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 2/20. Fares are subject to change and may not be available on all flights or dates of travel.
STL — IAD
Jan 7 — Jan 141
Wed 1/7
Wed 1/14
1 adult, Economy
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Find cheap flights from St. Louis to Dulles Intl with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

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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 43 days in advance, depart on a Friday or Tuesday and return on a Wednesday

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 December 8, 2025.

This Frontier deal was found by Cheapflights users on 12/6. 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.
Mon 12/1510:47 amSTL - IAD
1 stop5h 38mFrontier
Thu 12/185:35 amIAD - STL
1 stop5h 05mFrontier
Deal found 12/6$208
This Frontier deal was found by Cheapflights users on 12/7. 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.
Thu 12/1810:42 amSTL - IAD
1 stop6h 34mFrontier
Thu 12/255:35 amIAD - STL
1 stop5h 05mFrontier
Deal found 12/7$212
This Booking.com deal was found by Cheapflights users on 12/5. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/199:07 amSTL - IAD
1 stop22h 44mFrontier
Thu 12/255:35 amIAD - STL
1 stop5h 05mFrontier
Deal found 12/5$220
This United Airlines deal was found by Cheapflights users on 12/6. 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.
Wed 12/243:10 pmSTL - IAD
1 stop5h 11mUnited Airlines
Wed 12/315:50 pmIAD - STL
Nonstop2h 32mUnited Airlines
Deal found 12/6$237
This Priceline deal was found by Cheapflights users on 12/7. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/2910:40 amSTL - IAD
1 stop9h 23mFrontier
Mon 2/21:31 pmIAD - STL
1 stop11h 02mFrontier
Deal found 12/7$242
This Gotogate deal was found by Cheapflights users on 12/6. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/184:27 pmSTL - IAD
1 stop22h 19mFrontier
Mon 12/299:58 pmIAD - STL
1 stop25h 35mFrontier
Deal found 12/6$247
This Kiwi.com deal was found by Cheapflights users on 12/7. 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 12/163:30 pmSTL - IAD
2 stops21h 59mFrontier
Mon 1/59:58 pmIAD - STL
1 stop25h 35mFrontier
Deal found 12/7$263
This Frontier deal was found by Cheapflights users on 12/8. 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.
Thu 12/1112:04 pmSTL - IAD
1 stop10h 06mFrontier
Sat 12/139:20 pmIAD - STL
1 stop12h 39mFrontier
Deal found 12/8$264
This Frontier deal was found by Cheapflights users on 12/6. 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.
Mon 12/1510:47 amSTL - IAD
1 stop11h 18mFrontier
Sun 12/215:35 amIAD - STL
1 stop5h 05mFrontier
Deal found 12/6$268

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 December 8, 2025.

Most accurate provider

eDreams
3 stars

Most trusted provider

eDreams
3 stars

Round-trip from

$199
(Booking.com)

One-way from

$64
(Priceline)

Popular in

July

Cheapest in

March

Average price

$379

Good round-trip deal

$567 or less

Good one-way deal

$215 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. 8% potential increase in price ($34 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 4% potential price decrease ($15 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
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 December 8, 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 1/6

8:30 am-11:40 am

Nonstop2h 10m

Washington, D.C. Dulles Intl

Tue 1/13

8:40 am-10:13 am

Nonstop2h 33m

$235

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Wed 12/24

3:10 pm-9:21 pm

1 stop5h 11m

Washington, D.C. Dulles Intl

Wed 12/31

5:50 pm-7:22 pm

Nonstop2h 32m

$237

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Wed 1/7

9:57 am-5:35 pm

1 stop6h 38m

Washington, D.C. Dulles Intl

Thu 1/22

5:50 pm-7:27 pm

Nonstop2h 37m

$291

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 1/30

9:57 am-5:35 pm

1 stop6h 38m

Washington, D.C. Dulles Intl

Tue 2/3

5:38 pm-11:59 pm

1 stop7h 21m

$296

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sat 1/17

6:30 am-11:46 am

1 stop4h 16m

Washington, D.C. Dulles Intl

Sun 1/18

8:40 am-10:13 am

Nonstop2h 33m

$307

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 3/17

5:00 pm-12:26 am

1 stop6h 26m

Washington, D.C. Dulles Intl

Tue 3/24

6:00 am-9:46 am

1 stop4h 46m

$315

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sat 1/10

7:10 am-2:45 pm

1 stop6h 35m

Washington, D.C. Dulles Intl

Sun 1/25

6:00 am-9:39 am

1 stop4h 39m

$318

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 12/25

7:00 am-12:13 pm

1 stop4h 13m

Washington, D.C. Dulles Intl

Fri 1/2

6:00 am-9:24 am

1 stop4h 24m

$325

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 3/20

7:10 am-2:39 pm

1 stop6h 29m

Washington, D.C. Dulles Intl

Tue 3/24

6:00 am-9:46 am

1 stop4h 46m

$326

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Wed 2/18

8:30 am-11:40 am

Nonstop2h 10m

$114

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/7

Showing 1-10 of 20 results
1
2

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 December.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy2 starsTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*1 star
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 eDreams to be most consistent on Cheapflights vs. eDreams Users can find the same prices on St. Louis-Washington, D.C. Dulles Intl Airport flight deals on Cheapflights vs. eDreams >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 eDreams the most. eDreams 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 December 5, 2025.

The best time to book flights from St. Louis to Washington, D.C. Dulles Intl Airport is 43 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 $259). 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 December 8, 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.

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
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 December 8, 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
8,011 reviews

Boarding

8.1

Crew

8.5

Overall

7.9

Entertainment

7.9

Food

7.3

Comfort

7.9

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.
Delta
7.9
Good
8,011 reviews
Delta
7.9
Good
8,011 reviews

Boarding

8.1

Crew

8.5

Overall

7.9

Entertainment

7.9

Food

7.3

Comfort

7.9

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.
United Airlines
7.4
Good
9,089 reviews
Delta
7.9
Good
8,011 reviews

Boarding

8.1

Crew

8.5

Overall

7.9

Entertainment

7.9

Food

7.3

Comfort

7.9

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.
American Airlines
7.2
Good
11,045 reviews
Delta
7.9
Good
8,011 reviews

Boarding

8.1

Crew

8.5

Overall

7.9

Entertainment

7.9

Food

7.3

Comfort

7.9

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.
Frontier
5.8
Fair
3,085 reviews
Delta
7.9
Good
8,011 reviews

Boarding

8.1

Crew

8.5

Overall

7.9

Entertainment

7.9

Food

7.3

Comfort

7.9

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.

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 6 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 10m. United Airlines provides one of the quickest options available for as low as $235. There are 694 mi between St. Louis and Washington, D.C. Dulles Intl Airport. Most flights are nonstop.

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

    Currently priced at $73, 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 $99 and $250, respectively. Frontier is 80% 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 $63. Delta flights start at $99 while deals on United Airlines start at $123 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 Copa Airlines (80%), Avianca (78%) or GoJet (71%) 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 $743 for a flight from St. Louis to Washington, D.C. Dulles Intl Airport. The cheapest flight overall is $136 while the most popular route, (Lambert-St Louis - Washington, D.C. Dulles Intl) is currently priced at $177.

  • 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 $259). 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
Owings Mills
Springfield
Hanover
Silver Spring
Fredericksburg
Fairfax
Linthicum Heights
Manassas
Rockville
Laurel
Towson
National Harbor
Bowie
Largo
McLean
Clinton

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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 December 8, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$113Average$184FlexibilityNo cancel feeOn-time62%
DeltaCheapest$124Average$274FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$250Average$365FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$261Average$457FlexibilityNo cancel feeOn-time69%

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