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Dulles Intl

$94+ 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 9/11. Fares are subject to change and may not be available on all flights or dates of travel.
STL — IAD
ago. 19 — ago. 261
mar. 8/19
mar. 8/26
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 November or January, booked 75 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 agosto 14, 2025.

Round-trip from

$173
(United Airlines)

One-way from

$94
(Priceline)

Popular in

July

Cheapest in

November

Average price

$349

Good round-trip deal

$727 or less

Good one-way deal

$256 or less
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 ($12 potential savings vs. average RT price).
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Average for round-trip flights in August 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 agosto 14, 2025.

This United Airlines deal was found by Cheapflights users on 8/13. 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.
jue. 9/48:15 amSTL - IAD
Nonstop2h 10mUnited Airlines
dom. 9/78:40 amIAD - STL
Nonstop2h 22mUnited Airlines
Deal found 8/13$173
This FlightHub deal was found by Cheapflights users on 8/14. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
vie. 8/222:01 pmSTL - IAD
1 stop9h 15mFrontier
lun. 8/256:10 amIAD - STL
1 stop7h 46mFrontier
Deal found 8/14$175
This United Airlines deal was found by Cheapflights users on 8/14. 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.
jue. 9/41:10 pmSTL - IAD
Nonstop2h 10mUnited Airlines
lun. 9/85:53 pmIAD - STL
1 stop6h 51mUnited Airlines
Deal found 8/14$183
This FlightHub deal was found by Cheapflights users on 8/14. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
dom. 8/2410:17 amSTL - IAD
1 stop22h 10mFrontier
dom. 9/71:55 pmIAD - STL
1 stop26h 09mFrontier
Deal found 8/14$184
This Frontier deal was found by Cheapflights users on 8/14. 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.
jue. 9/44:00 pmSTL - IAD
1 stop7h 15mFrontier
dom. 9/710:09 pmIAD - STL
2 stops17h 55mFrontier
Deal found 8/14$186
This FlightHub deal was found by Cheapflights users on 8/14. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
jue. 10/2311:32 amSTL - IAD
1 stop11h 39mFrontier
dom. 10/266:15 amIAD - STL
1 stop5h 22mFrontier
Deal found 8/14$187
This FlightHub deal was found by Cheapflights users on 8/14. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
jue. 10/96:05 pmSTL - IAD
1 stop25h 48mFrontier
dom. 10/126:15 amIAD - STL
1 stop5h 22mFrontier
Deal found 8/14$189
This Frontier deal was found by Cheapflights users on 8/14. 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.
jue. 9/44:00 pmSTL - IAD
2 stops16h 17mFrontier
lun. 9/86:10 amIAD - STL
1 stop9h 54mFrontier
Deal found 8/14$190
This United Airlines deal was found by Cheapflights users on 8/12. 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.
mié. 9/36:35 amSTL - IAD
1 stop4h 20mUnited Airlines
mar. 9/168:20 amIAD - STL
1 stop6h 59mUnited Airlines
Deal found 8/12$193
This Expedia deal was found by Cheapflights users on 8/13. 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.
jue. 11/1310:17 amSTL - IAD
2 stops12h 54mFrontier
vie. 11/146:00 amIAD - STL
1 stop5h 07mFrontier
Deal found 8/13$196
This Delta deal was found by Cheapflights users on 8/14. 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.
vie. 9/125:11 pmSTL - IAD
1 stop6h 02mDelta
dom. 9/146:00 amIAD - STL
1 stop4h 33mDelta
Deal found 8/14$197
This FlightHub deal was found by Cheapflights users on 8/14. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
vie. 9/261:57 pmSTL - IAD
1 stop27h 27mFrontier
lun. 9/296:10 amIAD - STL
1 stop9h 54mFrontier
Deal found 8/14$198

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 agosto 14, 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

jue. 9/4

8:15 am-11:25 am

Nonstop2h 10m

Washington, D.C. Dulles Intl

dom. 9/7

8:40 am-10:02 am

Nonstop2h 22m

$173

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

jue. 9/18

8:15 am-11:25 am

Nonstop2h 10m

Washington, D.C. Dulles Intl

dom. 9/21

8:40 am-10:02 am

Nonstop2h 22m

$173

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

lun. 9/8

5:30 pm-12:32 am

1 stop6h 02m

Washington, D.C. Dulles Intl

mar. 9/9

8:40 am-10:02 am

Nonstop2h 22m

$183

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

lun. 9/8

1:10 pm-4:20 pm

Nonstop2h 10m

Washington, D.C. Dulles Intl

mié. 9/10

8:20 am-2:19 pm

1 stop6h 59m

$183

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

jue. 9/4

1:10 pm-4:20 pm

Nonstop2h 10m

Washington, D.C. Dulles Intl

lun. 9/8

5:53 pm-11:44 pm

1 stop6h 51m

$183

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

mar. 9/9

8:15 am-11:25 am

Nonstop2h 10m

Washington, D.C. Dulles Intl

mar. 9/16

8:20 am-2:19 pm

1 stop6h 59m

$183

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

mié. 9/3

1:10 pm-4:20 pm

Nonstop2h 10m

Washington, D.C. Dulles Intl

mar. 9/16

8:20 am-2:19 pm

1 stop6h 59m

$183

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

jue. 9/18

8:15 am-11:25 am

Nonstop2h 10m

Washington, D.C. Dulles Intl

lun. 9/22

3:55 pm-7:27 pm

1 stop4h 32m

$183

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

dom. 8/24

10:17 am-9:27 am

1 stop22h 10m

Washington, D.C. Dulles Intl

dom. 9/7

1:55 pm-3:04 pm

1 stop26h 09m

$184

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

jue. 9/18

4:00 pm-12:15 am

1 stop7h 15m

Washington, D.C. Dulles Intl

dom. 9/21

10:09 pm-3:04 pm

2 stops17h 55m

$186

Flights are sorted by cheapest round-trip flights first.

Deals found on 8/12

Showing 1-10 of 20 results
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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

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 August 8, 2025.

The best time to book flights from St. Louis to Washington, D.C. Dulles Intl Airport is 75 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, July is the cheapest month in which you can book a flight from St. Louis to Washington, D.C. Dulles Intl Airport (average of $302). Flying from St. Louis to Washington, D.C. Dulles Intl Airport in April is currently the most expensive (average of $337). 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 agosto 14, 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 79% on the cost of your flight, compared to a flight at noon.

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 agosto 14, 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
8.0
Very good
7,980 reviews

Overall

8.0

Entertainment

7.9

Comfort

7.9

Boarding

8.2

Crew

8.5

Food

7.3

Reviews

1 / 20
10.0
Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!
Delta
8.0
Very good
7,980 reviews
Delta
8.0
Very good
7,980 reviews

Overall

8.0

Entertainment

7.9

Comfort

7.9

Boarding

8.2

Crew

8.5

Food

7.3

Reviews

1 / 20
10.0
Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!
United Airlines
7.4
Good
8,916 reviews
Delta
8.0
Very good
7,980 reviews

Overall

8.0

Entertainment

7.9

Comfort

7.9

Boarding

8.2

Crew

8.5

Food

7.3

Reviews

1 / 20
10.0
Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!
American Airlines
7.2
Good
10,000 reviews
Delta
8.0
Very good
7,980 reviews

Overall

8.0

Entertainment

7.9

Comfort

7.9

Boarding

8.2

Crew

8.5

Food

7.3

Reviews

1 / 20
10.0
Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!

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 5 outbound flights to Washington, D.C. Dulles Intl per day from 3 airlines. Lambert-St Louis is conveniently located just 12.7 mi from St. Louis’s city center.

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

    Currently priced at $129, American Airlines will fly you from St. Louis to Washington, D.C. Dulles Intl Airport and back. In addition to American Airlines, 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 $168 and $209, respectively. American Airlines is 65% 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 $94. United Airlines flights start at $97 while deals on Delta start at $99 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 Avianca (72%), Copa Airlines (72%) or GoJet (70%) 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 $1,188 for a flight from St. Louis to Washington, D.C. Dulles Intl Airport. The cheapest flight overall is $219 while the most popular route, (Lambert-St Louis - Washington, D.C. Dulles Intl) is currently priced at $173.

  • 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, July is the cheapest month in which you can book a flight from St. Louis to Washington, D.C. Dulles Intl Airport (average of $302). Flying from St. Louis to Washington, D.C. Dulles Intl Airport in April is currently the most expensive (average of $337). 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
Woodbridge
Arlington
Alexandria
Tysons
Silver Spring
Springfield
Fredericksburg
Gaithersburg
Towson
Linthicum Heights
Fairfax
Manassas
Falls Church
Laurel
Rockville
Oxon Hill
National Harbor
Dundalk
Waldorf
Bowie

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Top 3 airlines flying from St. Louis to Dulles Intl

Discover the top 3 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 agosto 14, 2025.
AirlineCheapestAverageFlexibilityOn-time
American AirlinesCheapest$129Average$315FlexibilityNo cancel feeOn-time71%
DeltaCheapest$168Average$273FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$209Average$442FlexibilityNo cancel feeOn-time69%

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