HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Dulles Intl

$76+ 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 7/28. Fares are subject to change and may not be available on all flights or dates of travel.
STL — IAD
Aug 5 — Aug 121
Wed 8/5
Wed 8/12
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

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

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.

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 July 6, 2026.

This Delta deal was found by Cheapflights users on 7/1. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/86:09 pm
STL
-
IAD
1 stop4h 17m
Delta
Mon 8/107:26 pm
IAD
-
STL
1 stop5h 32m
Delta
Deal found 7/1$273
This Booking.com deal was found by Cheapflights users on 7/5. 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.
Thu 7/307:10 pm
STL
-
IAD
1 stop12h 10m
Frontier
Mon 8/37:18 pm
IAD
-
STL
1 stop5h 41m
Frontier
Deal found 7/5$275
This Delta deal was found by Cheapflights users on 7/2. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/236:00 am
STL
-
IAD
1 stop4h 37m
Delta
Wed 7/298:27 am
IAD
-
STL
1 stop4h 50m
Delta
Deal found 7/2$276
This CheapOair deal was found by Cheapflights users on 7/1. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/234:09 pm
STL
-
IAD
1 stop25h 24m
Frontier
Mon 7/277:18 pm
IAD
-
STL
1 stop5h 41m
Frontier
Deal found 7/1$278
This Kiwi.com deal was found by Cheapflights users on 7/3. 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 7/216:34 pm
STL
-
IAD
2 stops14h 42m
Frontier
Tue 7/287:49 am
IAD
-
STL
1 stop10h 48m
Frontier
Deal found 7/3$279
This Kiwi.com deal was found by Cheapflights users on 7/3. 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 10/1510:35 am
STL
-
IAD
1 stop6h 01m
Frontier
Sun 10/189:16 pm
IAD
-
STL
1 stop13h 24m
Frontier
Deal found 7/3$280
This Trip.com deal was found by Cheapflights users on 7/5. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/34:57 pm
STL
-
IAD
1 stop4h 55m
Frontier
Wed 8/511:11 am
IAD
-
STL
1 stop13h 48m
Frontier
Deal found 7/5$281
This Frontier deal was found by Cheapflights users on 7/4. 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.
Sat 8/84:57 pm
STL
-
IAD
1 stop4h 55m
Frontier
Mon 8/177:18 pm
IAD
-
STL
1 stop5h 41m
Frontier
Deal found 7/4$284
This United Airlines deal was found by Cheapflights users on 7/6. 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.
Sat 8/18:43 am
STL
-
IAD
Nonstop2h 12m
United Airlines
Thu 8/206:15 am
IAD
-
STL
1 stop4h 57m
United Airlines
Deal found 7/6$285
This Kiwi.com deal was found by Cheapflights users on 7/4. 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 8/66:34 pm
STL
-
IAD
2 stops14h 51m
Frontier
Sun 8/168:33 pm
IAD
-
STL
1 stop13h 24m
Frontier
Deal found 7/4$288

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 July 6, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$273
(American Airlines)

One-way from

$76
(Kiwi.com)

Popular in

August

Cheapest in

February

Average price

$397

Good round-trip deal

$667 or less

Good one-way deal

$222 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. 11% potential increase in price ($46 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 4% potential price decrease ($18 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in July 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 July 6, 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

Mon 8/3

12:55 pm-4:07 pm

Nonstop2h 12m

Washington, D.C. Dulles Intl

Mon 8/10

10:10 pm-11:32 pm

Nonstop2h 22m

$297

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sun 9/20

6:00 am-11:31 am

1 stop4h 31m

Washington, D.C. Dulles Intl

Wed 9/23

10:15 am-3:54 pm

1 stop6h 39m

$329

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 8/27

10:53 am-5:37 pm

1 stop5h 44m

Washington, D.C. Dulles Intl

Sun 8/30

5:45 pm-7:11 pm

Nonstop2h 26m

$338

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 7/28

6:00 am-11:37 am

1 stop4h 37m

Washington, D.C. Dulles Intl

Sat 8/1

5:21 pm-8:37 pm

1 stop4h 16m

$347

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Wed 7/29

6:00 am-11:37 am

1 stop4h 37m

Washington, D.C. Dulles Intl

Sat 8/1

5:21 pm-8:37 pm

1 stop4h 16m

$347

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Mon 8/3

8:43 am-11:55 am

Nonstop2h 12m

Washington, D.C. Dulles Intl

Thu 8/13

10:35 am-3:38 pm

1 stop6h 03m

$372

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 9/24

8:30 am-11:46 am

Nonstop2h 16m

Washington, D.C. Dulles Intl

Sat 9/26

10:30 am-2:16 pm

1 stop4h 46m

$384

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 7/21

6:09 pm-11:13 pm

1 stop4h 04m

Washington, D.C. Dulles Intl

Thu 7/30

6:00 am-9:31 am

1 stop4h 31m

$385

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 7/14

10:19 am-4:41 pm

1 stop5h 22m

Washington, D.C. Dulles Intl

Wed 7/29

5:26 pm-8:37 pm

1 stop4h 11m

$385
Quickest round-trip

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Mon 8/17

1:00 pm-4:06 pm

Nonstop2h 06m

Washington, D.C. Dulles Intl

Sat 8/22

5:45 pm-7:11 pm

Nonstop2h 26m

$438

Flights are sorted by cheapest round-trip flights first.

Deals found on 7/1

Showing 1-10 of 22 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 July.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy1 starTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust 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

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 August is currently the most expensive (average of $567). 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 July 6, 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 July 6, 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
7.8
Good
8,451 reviews

Entertainment

7.8

Overall

7.8

Boarding

8.1

Comfort

7.8

Food

7.2

Crew

8.5

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
7.8
Good
8,451 reviews
Delta
7.8
Good
8,451 reviews

Entertainment

7.8

Overall

7.8

Boarding

8.1

Comfort

7.8

Food

7.2

Crew

8.5

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
9,945 reviews
Delta
7.8
Good
8,451 reviews

Entertainment

7.8

Overall

7.8

Boarding

8.1

Comfort

7.8

Food

7.2

Crew

8.5

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
11,783 reviews
Delta
7.8
Good
8,451 reviews

Entertainment

7.8

Overall

7.8

Boarding

8.1

Comfort

7.8

Food

7.2

Crew

8.5

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
5.6
Fair
2,841 reviews
Delta
7.8
Good
8,451 reviews

Entertainment

7.8

Overall

7.8

Boarding

8.1

Comfort

7.8

Food

7.2

Crew

8.5

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 7 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. United Airlines provides one of the quickest options available for as low as $297. 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 $98 and $257, respectively. Frontier is 76% 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 $128 while deals on United Airlines start at $131 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 (91%), Avianca (90%) or Lufthansa (87%) 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 $664 for a flight from St. Louis to Washington, D.C. Dulles Intl Airport. The cheapest flight overall is $138 while the most popular route, (Lambert-St Louis - Washington, D.C. Dulles Intl) is currently priced at $260.

  • 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 August is currently the most expensive (average of $567). 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
Arlington
Tysons
Owings Mills
Springfield
Lanham
Reston
Herndon
Rockville
Hyattsville
Falls Church
Fredericksburg
Hanover
Chantilly
Manassas
Silver Spring
Laurel
Clinton
Hunt Valley
Cordova

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

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 July 6, 2026.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$90Average$201FlexibilityNo cancel feeOn-time62%
DeltaCheapest$98Average$355FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$257Average$323FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$271Average$472FlexibilityNo cancel feeOn-time69%

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.