HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
St. Louis

$70+ Cheap flights from Dulles Intl (IAD) to St. Louis (STL)

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 9/10. Fares are subject to change and may not be available on all flights or dates of travel.
IAD — STL
Aug 10 — Aug 171
Sun 8/10
Sun 8/17
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from Dulles Intl to St. Louis 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.

Cheapflights Tip: The best prices from Washington, D.C. Dulles Intl to Lambert-St Louis are usually found in July or May, booked 70 days in advance, depart on a Wednesday or Sunday and return on a Friday

Cheap flight deals from Dulles Intl to St. Louis

Discover tips and strategies to find the most affordable flight options for your journey from Dulles Intl (IAD) to St. Louis (STL). 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 August 5, 2025.

Round-trip from

$183
(United Airlines)

One-way from

$70
(United Airlines)

Popular in

December

Cheapest in

July

Average price

$408

Good round-trip deal

$504 or less

Good one-way deal

$244 or less
From Washington, D.C. Dulles Intl to Lambert-St Louis
Search Deals
One-way flight from Washington, D.C. Dulles Intl to Lambert-St Louis
Search Deals
Highest demand for flights based on searches. 13% potential increase in price ($60 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($10 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in August 2025
Search Deals
Price to beat on a round-trip flight from Washington, D.C. Dulles Intl to Lambert-St Louis.
Search Deals
Price to beat on a one-way flight from Washington, D.C. Dulles Intl to Lambert-St Louis.
Search Deals

Find flight deals from Dulles Intl to St. Louis

Cheapest flights from Dulles Intl to St. Louis
Explore the most affordable flight options available from Dulles Intl to St. Louis. Find the lowest fares from popular airlines and budget airlines, with prices last updated on August 5, 2025.

This United Airlines deal was found by Cheapflights users on 8/5. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/210:15 amIAD - STL
1 stop6h 29mUnited Airlines
Tue 9/98:15 amSTL - IAD
Nonstop2h 10mUnited Airlines
Deal found 8/5$183
This Delta deal was found by Cheapflights users on 8/5. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/286:00 amIAD - STL
1 stop4h 15mDelta
Sun 8/316:00 amSTL - IAD
1 stop4h 44mDelta
Deal found 8/5$197
This United Airlines deal was found by Cheapflights users on 8/4. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/203:45 pmIAD - STL
1 stop6h 47mUnited Airlines
Mon 9/228:15 amSTL - IAD
Nonstop2h 10mUnited Airlines
Deal found 8/4$204
This Frontier deal was found by Cheapflights users on 8/4. 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.
Thu 8/76:10 amIAD - STL
1 stop8h 24mFrontier
Sat 8/92:52 pmSTL - IAD
1 stop7h 34mFrontier
Deal found 8/4$208
This Frontier deal was found by Cheapflights users on 8/4. 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 8/306:10 amIAD - STL
1 stop8h 23mFrontier
Sun 8/312:02 pmSTL - IAD
1 stop5h 46mFrontier
Deal found 8/4$212
This FlightHub deal was found by Cheapflights users on 8/3. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/166:10 amIAD - STL
1 stop8h 49mFrontier
Sun 8/175:40 pmSTL - IAD
1 stop18h 11mFrontier
Deal found 8/3$215
This Mytrip deal was found by Cheapflights users on 8/4. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/137:14 pmIAD - STL
1 stop18h 53mFrontier
Sun 9/144:00 pmSTL - IAD
1 stop7h 15mFrontier
Deal found 8/4$217
This Frontier deal was found by Cheapflights users on 8/5. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/146:10 amIAD - STL
1 stop8h 24mFrontier
Fri 8/152:27 pmSTL - IAD
1 stop15h 07mFrontier
Deal found 8/5$218
This Delta deal was found by Cheapflights users on 8/4. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/2512:35 pmIAD - STL
1 stop4h 30mDelta
Mon 9/295:11 pmSTL - IAD
1 stop6h 02mDelta
Deal found 8/4$219
This United Airlines deal was found by Cheapflights users on 8/5. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 9/78:40 amIAD - STL
Nonstop2h 22mUnited Airlines
Mon 9/86:35 amSTL - IAD
1 stop4h 20mUnited Airlines
Deal found 8/5$220
This FlightHub deal was found by Cheapflights users on 8/5. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 9/77:14 pmIAD - STL
1 stop18h 48mFrontier
Sun 9/214:00 pmSTL - IAD
1 stop7h 15mFrontier
Deal found 8/5$225

Cheapflights Fare Finder

 
Customize your flight search to find flights from Dulles Intl to St. Louis 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 August 5, 2025.
Use the filters below to find and compare flights from Washington, D.C. Dulles Intl Airport to St. Louis that are best for you.

Fly from

Dulles Intl

Fly to

St. Louis

Route

Depart

Return

Price

Washington, D.C.St. Louis

IAD - STL

IADSTL

Washington, D.C. Dulles Intl

Tue 9/2

10:15 am-3:44 pm

1 stop6h 29m

Lambert-St Louis

Tue 9/9

8:15 am-11:25 am

Nonstop2h 10m

$183

Washington, D.C.St. Louis

IAD - STL

IADSTL

Washington, D.C. Dulles Intl

Thu 8/28

6:00 am-9:32 am

1 stop4h 32m

Lambert-St Louis

Sun 8/31

6:00 am-11:44 am

1 stop4h 44m

$197

Washington, D.C.St. Louis

IAD - STL

IADSTL

Washington, D.C. Dulles Intl

Sat 9/20

3:45 pm-9:32 pm

1 stop6h 47m

Lambert-St Louis

Mon 9/22

8:15 am-11:25 am

Nonstop2h 10m

$204

Washington, D.C.St. Louis

IAD - STL

IADSTL

Washington, D.C. Dulles Intl

Thu 8/14

6:10 am-1:34 pm

1 stop8h 24m

Lambert-St Louis

Sat 8/16

2:52 pm-11:26 pm

1 stop7h 34m

$208

Washington, D.C.St. Louis

IAD - STL

IADSTL

Washington, D.C. Dulles Intl

Sat 8/30

6:10 am-1:33 pm

1 stop8h 23m

Lambert-St Louis

Sun 8/31

2:02 pm-8:48 pm

1 stop5h 46m

$212

Washington, D.C.St. Louis

IAD - STL

IADSTL

Washington, D.C. Dulles Intl

Sat 8/16

6:10 am-1:59 pm

1 stop8h 49m

Lambert-St Louis

Sun 8/17

5:40 pm-12:51 pm

1 stop18h 11m

$215

Washington, D.C.St. Louis

IAD - STL

IADSTL

Washington, D.C. Dulles Intl

Sat 9/13

7:14 pm-1:07 pm

1 stop18h 53m

Lambert-St Louis

Sun 9/14

4:00 pm-12:15 am

1 stop7h 15m

$217

Washington, D.C.St. Louis

IAD - STL

IADSTL

Washington, D.C. Dulles Intl

Thu 8/14

6:10 am-1:34 pm

1 stop8h 24m

Lambert-St Louis

Mon 8/18

2:37 pm-6:34 am

1 stop14h 57m

$218

Washington, D.C.St. Louis

IAD - STL

IADSTL

Washington, D.C. Dulles Intl

Thu 9/25

12:35 pm-4:05 pm

1 stop4h 30m

Lambert-St Louis

Mon 9/29

5:11 pm-12:13 am

1 stop6h 02m

$219

Washington, D.C.St. Louis

IAD - STL

IADSTL

Washington, D.C. Dulles Intl

Sun 9/7

8:40 am-10:02 am

Nonstop2h 22m

Lambert-St Louis

Mon 9/8

6:35 am-11:55 am

1 stop4h 20m

$220

Flights are sorted by cheapest round-trip flights first.

Deals found on 8/4

Showing 1-10 of 22 results
1
2
3

The best insider tips for Washington, D.C. Dulles Intl Airport to St. Louis 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 Washington, D.C. Dulles Intl Airport to St. Louis trip
Airports
IAD

For quick check-in at IAD, locate your airline’s counter by walking around the first row. Counters are like an island with desks on both sides.

Read more about IADby Ramsey Qubein
STL

Use the MetroLink light rail for a convenient, economical ride from STL to downtown St. Louis. It takes about 40 minutes and avoids traffic.

Read more about STLby Taryn White
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 Dulles Intl to St. Louis

Have a flexible travel schedule? Discover the best time to fly to St. Louis from Dulles Intl 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 Washington, D.C. Dulles Intl Airport to St. Louis

How far ahead should I book a flight from Washington, D.C. Dulles Intl Airport to St. Louis?

Use this chart to determine the optimal time to book a round-trip flight from Dulles Intl to St. Louis. Price data was last updated on August 1, 2025.

The best time to book flights from Washington, D.C. Dulles Intl Airport to St. Louis is 69 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 Washington, D.C. Dulles Intl Airport to St. Louis?

Currently, August is the cheapest month in which you can book a flight from Washington, D.C. Dulles Intl Airport to St. Louis (average of $311). Flying from Washington, D.C. Dulles Intl Airport to St. Louis in March is currently the most expensive (average of $356). 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 IAD to STL?

Find hourly flight availability from Dulles Intl to St. Louis. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated August 5, 2025.

It’s typically best to fly out from Washington, D.C. Dulles Intl Airport to St. Louis in the evening. Doing so could potentially save you 44% on the flight price compared to flying in the afternoon, which is usually more expensive.

What is the cheapest day to fly from Washington, D.C. Dulles Intl Airport to St. Louis?

Use this chart to determine the cheapest time to fly round-trip from Dulles Intl to St. Louis. Price data was last updated on August 3, 2025.

Travelers seeking maximum savings on their Washington, D.C. Dulles Intl Airport to St. Louis flight should consider departing on Wednesday at noon when fares are most often at their lowest. Tuesday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.

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

Explore weekly flight availability from Dulles Intl to St. Louis. 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 August 5, 2025.

The most flights from IAD to STL are scheduled on a Monday (8 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (8 on average).

Reviews of airlines servicing St. Louis

Get insights into the airlines that provide service to St. Louis. 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 St. Louis. Reviews last updated August 5, 2025.
Get a feel of what it's like to fly with Southwest, Delta, and United Airlines from Washington, D.C. Dulles Intl Airport to St. Louis by reading reviews from past customers. Users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,246 reviews

Comfort

8.0

Overall

8.0

Entertainment

7.5

Boarding

8.1

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Southwest
8.0
Very good
4,246 reviews
Southwest
8.0
Very good
4,246 reviews

Comfort

8.0

Overall

8.0

Entertainment

7.5

Boarding

8.1

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Delta
8.0
Very good
7,985 reviews
Southwest
8.0
Very good
4,246 reviews

Comfort

8.0

Overall

8.0

Entertainment

7.5

Boarding

8.1

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
United Airlines
7.4
Good
8,916 reviews
Southwest
8.0
Very good
4,246 reviews

Comfort

8.0

Overall

8.0

Entertainment

7.5

Boarding

8.1

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
American Airlines
7.2
Good
10,000 reviews
Southwest
8.0
Very good
4,246 reviews

Comfort

8.0

Overall

8.0

Entertainment

7.5

Boarding

8.1

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Frontier
5.9
Fair
3,232 reviews
Southwest
8.0
Very good
4,246 reviews

Comfort

8.0

Overall

8.0

Entertainment

7.5

Boarding

8.1

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.

Related info for your journey

Find useful and relevant information for your journey from Dulles Intl to St. Louis. 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 into for flights to St. Louis from Washington, D.C. Dulles Intl?

    If you book a flight to St. Louis from Washington, D.C. Dulles Intl, you will be flying to Lambert-St Louis, which is the city’s only airport. Lambert-St Louis (STL) is located 12.7 mi from the center of St. Louis. There are 8 flights from Washington, D.C. Dulles Intl to Lambert-St Louis per day from 3 different airlines.

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

    Cheapflights users have booked flights from Washington, D.C. Dulles Intl Airport to St. Louis round-trip from $183. Another airline that can offer you cheap pricing is Delta. These flights start at 54% lower than the current average price 3 months from now.

  • What are the most reliable airlines from Washington, D.C. Dulles Intl Airport to St. Louis?

    Consider GoJet (73%), Avianca (72%) or Copa Airlines (72%) when booking your flight. These represent the most reliable airlines when flying from Washington, D.C. Dulles Intl Airport to St. Louis.

  • What are the cheapest flights from Washington, D.C. Dulles Intl Airport to St. Louis?

    Looking for the cheapest flight from Washington, D.C. Dulles Intl Airport to St. Louis? While on average our users pay $466, our data indicates the cheapest price to be $189. The most popular route (Washington, D.C. Dulles Intl - Lambert-St Louis), is priced around $193.

  • Can I find deals for flights from Dulles Intl to St. Louis that include hotel bookings?

    Yes. In addition to deals on Dulles Intl to St. Louis flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Dulles Intl to St. Louis?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Dulles Intl to St. Louis.

  • Can I find deals for business class flights from Dulles Intl to St. Louis?

    Yes. Cheapflights offers flight deals from Dulles Intl to St. Louis 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 Washington, D.C. Dulles Intl Airport to St. Louis?

    Currently, August is the cheapest month in which you can book a flight from Washington, D.C. Dulles Intl Airport to St. Louis (average of $311). Flying from Washington, D.C. Dulles Intl Airport to St. Louis in March is currently the most expensive (average of $356). 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
O'Fallon
Maryland Heights
Fairview Heights
Collinsville
Eureka
St. Peters
Glencoe
Alton
Chesterfield
Farmington
Festus

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.

Alternative routes for Dulles Intl to St. Louis

See prices for flight routes from nearby airports that may be better suited for you.
Dulles Intl to Kansas City flights
Baltimore to Kansas City flights
Baltimore to St. Louis flights
Reagan-National to St. Louis flights
Reagan-National to Kansas City flights
Dulles Intl to Springfield flights
Baltimore to Springfield flights
Reagan-National to Springfield flights
Baltimore to Columbia flights
Dulles Intl to Columbia flights
Baltimore to Joplin flights
Reagan-National to Columbia flights
Dulles Intl to Joplin flights
Reagan-National to Joplin flights
Baltimore to Quincy flights
Baltimore to Fort Leonard Wood flights
Dulles Intl to Fort Leonard Wood flights
Dulles Intl to Kirksville flights
Baltimore to Kirksville flights
Dulles Intl to Branson flights
Reagan-National to Fort Leonard Wood flights
Reagan-National to Branson flights
Baltimore to Branson flights

Top 3 airlines flying from Dulles Intl to St. Louis

Discover the top 3 airlines that operate flights from Dulles Intl to St. Louis. 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 August 5, 2025.
AirlineCheapestAverageFlexibilityOn-time
DeltaCheapest$198Average$290FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$256Average$478FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$276Average$321FlexibilityNo cancel feeOn-time71%

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.