HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Dulles Intl

$115+ 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 5/28. Fares are subject to change and may not be available on all flights or dates of travel.
STL — IAD
Jan 28 — Feb 41
Tue 1/28
Tue 2/4
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.

The best prices from Lambert-St Louis to Washington, D.C. Dulles Intl are usually found in January or November, booked 75 days in advance, depart on a Friday or Wednesday 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 January 23, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$233
(Delta)

One-way from

$115
(United Airlines)

Popular in

April

Cheapest in

January

Average price

$299

Good round-trip deal

$739 or less

Good one-way deal

$237 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. 4% potential increase in price ($19 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 January 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

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 January 23, 2025.

This Delta deal was found by Cheapflights users on 1/22. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 2/154:40 pmSTL - IAD
1 stop6h 40mDelta
Sun 2/236:00 amIAD - STL
1 stop6h 46mDelta
Deal found 1/22$233
This United Airlines deal was found by Cheapflights users on 1/22. 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.
Thu 2/278:25 amSTL - IAD
Nonstop2h 09mUnited Airlines
Fri 2/288:30 amIAD - STL
1 stop7h 06mUnited Airlines
Deal found 1/22$240
This CheapOair deal was found by Cheapflights users on 1/23. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 3/711:00 amSTL - IAD
1 stop22h 32mFrontier
Sun 3/165:54 pmIAD - STL
1 stop16h 42mFrontier
Deal found 1/23$246
This American Airlines deal was found by Cheapflights users on 1/22. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/15:55 amSTL - IAD
2 stops10h 02mAmerican Airlines
Fri 4/49:10 amIAD - STL
1 stop4h 43mAmerican Airlines
Deal found 1/22$320

Find flights from St. Louis to Dulles Intl within your budget

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 January 23, 2025.

Fly from

Any airport

Fly to

Any airport

Route

Depart

Return

Price

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sat 2/15

4:40 pm-12:20 am

1 stop6h 40m

Washington, D.C. Dulles Intl

Sun 2/23

6:00 am-11:46 am

1 stop6h 46m

$233

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 2/27

8:25 am-11:34 am

Nonstop2h 09m

Washington, D.C. Dulles Intl

Fri 2/28

8:30 am-2:36 pm

1 stop7h 06m

$240

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 3/7

11:00 am-10:32 am

1 stop22h 32m

Washington, D.C. Dulles Intl

Sun 3/16

5:54 pm-9:36 am

1 stop16h 42m

$246

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 4/1

11:55 am-11:58 pm

2 stops11h 03m

Washington, D.C. Dulles Intl

Sat 4/5

5:00 am-8:30 am

1 stop4h 30m

$320

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Wed 5/28

8:15 am-11:23 am

Nonstop2h 08m

$115

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sat 5/3

7:20 am-12:59 pm

1 stop4h 39m

$119

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 4/10

4:57 pm-5:02 pm

1 stop23h 05m

$136

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 3/20

6:32 pm-11:58 pm

1 stop4h 26m

$139

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 2/27

4:00 pm-4:15 pm

3 stops23h 15m

$155

Flights are sorted by cheapest round-trip flights first.

Deals found on 1/22

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 January.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy1 starTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*3 stars
eDreamsPrice Accuracy3 starsTrust Score*3 stars
PricelinePrice Accuracy2 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.

Travel insights for flights from St. Louis to Dulles Intl

Get recent, data-driven insights about flights from St. Louis to Dulles Intl including ideal travel times, pricing trends, and more.

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 January 17, 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, August is the cheapest month in which you can book a flight from St. Louis to Washington, D.C. Dulles Intl Airport (average of $309). Flying from St. Louis to Washington, D.C. Dulles Intl Airport in June is currently the most expensive (average of $389). 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 January 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 79% on the cost of your flight, compared to a flight at noon.

Weekly flight availability from St. Louis to Washington, D.C. Dulles Intl Airport

Explore weekly flight availability from St. Louis to Dulles Intl. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated January 23, 2025.

The most flights from STL to IAD are scheduled on a Monday (6 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (6 on average).

Rainfall in Dulles Intl by month

Plan your trip to Dulles Intl by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Washington, D.C. Dulles Intl Airport ranges from 2.6 - 4.0 inches per month. May is typically the wettest month, when rainfall can reach 4.0 in. February is typically the driest time to visit Washington, D.C. Dulles Intl Airport when rainfall is around 2.6 in.

Temperature in Dulles Intl by month

Plan your trip to Dulles Intl by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Washington, D.C. Dulles Intl Airport, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 80.6 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 35.6 F).

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 January 23, 2025.
To help decide which airline to fly from St. Louis to Washington, D.C., see what other customers have to say about United Airlines, American Airlines and Delta. In addition to providing an overall rating, users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Delta
8.0
Very good
8,512 reviews

Crew

8.6

Boarding

8.2

Food

7.3

Overall

8.0

Comfort

8.0

Entertainment

7.9

Reviews

1 / 10

Delta has consistently been the best U.S. airline for my travels and this flight was no exception

Delta
8.0
Very good
8,512 reviews
Delta
8.0
Very good
8,512 reviews

Crew

8.6

Boarding

8.2

Food

7.3

Overall

8.0

Comfort

8.0

Entertainment

7.9

Reviews

1 / 10

Delta has consistently been the best U.S. airline for my travels and this flight was no exception

United Airlines
7.4
Good
8,970 reviews
Delta
8.0
Very good
8,512 reviews

Crew

8.6

Boarding

8.2

Food

7.3

Overall

8.0

Comfort

8.0

Entertainment

7.9

Reviews

1 / 10

Delta has consistently been the best U.S. airline for my travels and this flight was no exception

American Airlines
7.2
Good
10,000 reviews
Delta
8.0
Very good
8,512 reviews

Crew

8.6

Boarding

8.2

Food

7.3

Overall

8.0

Comfort

8.0

Entertainment

7.9

Reviews

1 / 10

Delta has consistently been the best U.S. airline for my travels and this flight was no exception

Frontier
6.1
Okay
3,441 reviews
Delta
8.0
Very good
8,512 reviews

Crew

8.6

Boarding

8.2

Food

7.3

Overall

8.0

Comfort

8.0

Entertainment

7.9

Reviews

1 / 10

Delta has consistently been the best U.S. airline for my travels and this flight was no exception

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 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 $233, Delta will fly you from St. Louis to Washington, D.C. Dulles Intl Airport and back. In addition to Delta, many other airlines offer competitively priced options for your trip. Search Cheapflights for deals from United Airlines and Frontier - these airlines can fly you to your destination from $240 and $246, respectively. Delta is 38% 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 United Airlines, which is currently one of the cheapest options available, starting at $115. Frontier flights start at $136 while deals on American Airlines start at $139 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 (80%), Copa Airlines (80%) or GoJet (75%) 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 $776 for a flight from St. Louis to Washington, D.C. Dulles Intl Airport. The cheapest flight overall is $114 while the most popular route, (Lambert-St Louis - Washington, D.C. Dulles Intl) is currently priced at $155.

  • 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, August is the cheapest month in which you can book a flight from St. Louis to Washington, D.C. Dulles Intl Airport (average of $309). Flying from St. Louis to Washington, D.C. Dulles Intl Airport in June is currently the most expensive (average of $389). 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 St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
Fairfax
Arlington
Alexandria
Springfield
Silver Spring
Rockville
Tysons
Gaithersburg
Fredericksburg
Linthicum Heights
Laurel
Falls Church
Greenbelt
Sterling
Easton
Oxon Hill
Herndon
Woodbridge
Bowie
Reston

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 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 January 23, 2025.
AirlineCheapestAverageFlexibilityOn-time
American AirlinesCheapest$129Average$298FlexibilityNo cancel feeOn-time71%
DeltaCheapest$177Average$264FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$211Average$453FlexibilityNo 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.