IAD - STL

$55 Find Cheap Flights from Washington Dulles Airport to St. Louis

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Dulles Intl to St. Louis departing on 12/4. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

KAYAK searches hundreds of travel sites at once for deals on flights to St. Louis

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Washington, D.C. to St. Louis, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Washington, D.C. to St. Louis, as well as popular online travel agencies
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Flight Deals

Cheap Flights from Dulles Intl to St. Louis (IAD-STL)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Dulles Intl to St. Louis that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Dulles Intl to St. Louis

Sat, Dec 6 - Fri, Dec 12
Frontier Logo
5:45 am - 10:33 pmIAD-STL
17h 48m2 stops
Frontier Logo
10:42 am - 11:05 pmSTL-IAD
11h 23m1 stop
$223Frontier
Find Deal
Tue, Nov 18 - Thu, Nov 20
Frontier Logo
8:40 am - 10:05 amIAD-STL
26h 25m2 stops
Frontier Logo
4:13 pm - 7:50 amSTL-IAD
14h 37m1 stop
$226Frontier
Find Deal
Sun, Nov 16 - Tue, Nov 18
Frontier Logo
6:00 am - 10:12 amIAD-STL
5h 12m1 stop
Frontier Logo
7:45 pm - 8:20 pmSTL-IAD
23h 35m2 stops
$228Frontier
Find Deal
Wed, Nov 12 - Thu, Nov 13
Multiple Airlines Logo
8:40 am - 10:12 amIAD-STL
26h 32m1 stop
Multiple Airlines Logo
7:02 pm - 7:51 pmSTL-IAD
23h 49m2 stops
$231Multiple Airlines
Find Deal
Thu, Nov 20 - Sun, Nov 23
Multiple Airlines Logo
6:55 am - 2:29 pmIAD-STL
8h 34m1 stop
Multiple Airlines Logo
11:08 am - 11:59 pmSTL-IAD
35h 51m2 stops
$237Multiple Airlines
Find Deal
Sat, Jan 17 - Mon, Jan 19
United Airlines Logo
8:40 am - 10:13 amIAD-STL
2h 33mnonstop
United Airlines Logo
8:30 am - 11:40 amSTL-IAD
2h 10mnonstop
$261United Airlines
Find Deal
Tue, Dec 2 - Wed, Dec 3
United Airlines Logo
6:30 am - 12:15 pmIAD-STL
6h 45m1 stop
United Airlines Logo
8:30 am - 11:40 amSTL-IAD
2h 10mnonstop
$273United Airlines
Find Deal
Thu, Jan 8 - Mon, Jan 12
American Airlines Logo
7:01 am - 6:14 pmIAD-STL
12h 13m2 stops
American Airlines Logo
3:54 pm - 11:12 pmSTL-IAD
6h 18m1 stop
$308American Airlines
Find Deal
Fri, Dec 5 - Wed, Dec 10
Delta Logo
12:19 pm - 4:35 pmIAD-STL
5h 16m1 stop
Delta Logo
10:45 am - 4:23 pmSTL-IAD
4h 38m1 stop
$317Delta
Find Deal
Tue, Dec 2 - Tue, Dec 9
Delta Logo
12:19 pm - 4:35 pmIAD-STL
5h 16m1 stop
Delta Logo
5:12 pm - 12:12 amSTL-IAD
6h 00m1 stop
$318Delta
Find Deal

Everything you should know

Our travelers' advice
AI-generated summary based on content written by travel experts
For quick navigation at Dulles, use the AeroTrain.
Use MetroLink for easy access from STL to downtown.
Expert advice
Expert advice
Expert advice
Expert advice
Top airlines
Frontier
Cheapest • from $223 (round-trip)
Delta
Best reviews • 7.9 score
Airline reviews
Airline reviews
+1
+1
Airline reviews
Airline reviews
+1
When to book
4 weeks
in advance
Our data shows that travelers who book at least 4 weeks in advance save around 50% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
August
Cheapest • 27% price drop
November
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
Cheapest round-trip
$223
Overall average: $470
Frontier
Sat 12/6Fri 12/12
IAD - STL • 2 stops
Cheapest non-stop
$261
Typical prices: $424-$598
United Airlines
Sat 1/17Mon 1/19
IAD - STL • Non-stop
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KAYAK searches 100s of sites at once to find you the best travel deals.
We hope you love your trip to St. Louis!
Booking Insights

KAYAK's insights & trends for Dulles Intl to St. Louis flights

Get data-powered insights and trends into flights from Dulles Intl to St. Louis to help you find the cheapest flights, the best time to fly and much more.

What’s the cheapest day of the week to fly from Washington Dulles Airport to St. Louis?

The average price of all round-trip flights from Washington, D.C. Dulles Intl Airport to St. Louis clicked on KAYAK for each day over the last 12 months.

For Washington Dulles Airport to St. Louis, Wednesday is the cheapest day to fly on average and Monday is the most expensive. Flying from St. Louis back to Washington Dulles Airport, the best deals are generally found on Friday, with Saturday being the most expensive.

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

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Washington, D.C. Dulles Intl Airport to St. Louis, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from Washington, D.C. Dulles Intl Airport to St. Louis is August, where tickets cost $290 (return) on average. On the other hand, the most expensive months are September and January, where the average cost of round-trip tickets is $505 and $478 respectively.

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

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from Washington, D.C. Dulles Intl Airport to St. Louis, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.

To get a below average price on the flight from Washington, D.C. Dulles Intl Airport to St. Louis, you should book around 4 weeks before departure, which saves you about 50% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 11 weeks before departure.

Expert advice

Expert advice for your flight from Dulles Intl to St. Louis

 
Snippets provided in this section are AI-generated based on a summarization of KAYAK-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.
KAYAK teamed up with top travel experts to share the best tips for your journey.
Airports
IAD

For quick navigation at Dulles, use the AeroTrain for Concourses A, B, and C. Mobile lounges connect to Concourse D.

Read more about IADby Stefanie Waldek
STL

Use MetroLink for easy access from STL to downtown St. Louis. The Red Line connects the airport to key city areas.

Read more about STLby Yulia Denisyuk
Our travel experts
Yulia Denisyuk

Yulia Denisyuk

Expert on STL

Yulia Denisyuk

Yulia Denisyuk

Yulia is a freelance journalist who’s dispatched from 90+ countries. Her work focuses on cultures, adventure trips and air travel, appearing in NatGeo, NYT, CNTraveler, and more. For past assignments, she’s stayed with nomads in Mongolia and learned the art of Imigongo in Rwanda. She’s based in Chicago; in winter she often questions that decision.

Read more
Stefanie Waldek

Stefanie Waldek

Expert on IAD

Stefanie Waldek

Stefanie Waldek

Stefanie Waldek is a freelance space, travel, and design writer based in Saratoga Springs, NY. Her words have appeared in Space.com, Travel + Leisure, Condé Nast Traveler, Architectural Digest, and House Beautiful, among other publications. An expert in aviation and expedition cruising, Stefanie is frequently up in the air or on the sea, likely en route to Antarctica or the Arctic.

Read more

Good to know

Low seasonJune
Cheapest flight$55
Best time to beat the crowds with an average 3% drop in price.
Most popular time to fly with an average 5% increase in price.
Flight from Washington Dulles Airport to St. Louis

When to book flights from Dulles Intl to St. Louis

Are your dates flexible? Find out the best times to travel from Dulles Intl to St. Louis based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking Washington Dulles Airport to St. Louis flights

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

    In the last 3 days, the lowest price for a flight from Washington, D.C. Dulles Intl Airport to St. Louis was $55 for a one-way ticket and $223 for a round-trip.

  • Do I need a passport to fly between Washington Dulles Airport and St. Louis?

    No, a passport isn't needed to fly from Washington Dulles Airport to St. Louis. However, local authorities might ask for an official ID.

  • Which airports will I be using when flying from Washington Dulles Airport to St. Louis?

    When flying out of Washington Dulles Airport you will be using Washington, D.C. Dulles Intl. You will be landing at St. Louis, also known as Lambert-St Louis.

  • Which airlines offer Wi-Fi service onboard planes from Washington Dulles Airport to St. Louis?

    Only American Airlines offers inflight Wi-Fi service on the Washington Dulles Airport to St. Louis flight route.

  • Which aircraft models fly most regularly from Washington Dulles Airport to St. Louis?

    The Canadair (Bombardier) Regional Jet CRJ-550 is the aircraft model that flies most regularly on the Washington Dulles Airport to St. Louis flight route.

  • Which airline alliances offer flights from Washington Dulles Airport to St. Louis?

    oneworld, SkyTeam, and Star Alliance are the airline alliances operating flights between Washington Dulles Airport and St. Louis, with oneworld being the most commonly used for this route.

  • On which days can I fly direct from Washington Dulles Airport to St. Louis?

    There are nonstop flights from Washington Dulles Airport to St. Louis on a daily basis.

  • Which is the best airline for flights from Washington, D.C. to St. Louis, Delta or United Airlines?

    The two airlines most popular with KAYAK users for flights from Washington, D.C. to St. Louis are Delta and United Airlines. With an average price for the route of $304 and an overall rating of 7.9, Delta is the most popular choice. United Airlines is also a great choice for the route, with an average price of $471 and an overall rating of 7.4.

  • How does KAYAK find such low prices on flights from Washington Dulles Airport to St. Louis?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Washington Dulles Airport to St. Louis.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Washington Dulles Airport to St. Louis?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to St. Louis from Washington Dulles Airport is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Washington Dulles Airport to St. Louis?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to St. Louis with an airline and back to Washington Dulles Airport with another airline. Booking your flights between Washington Dulles Airport and STL can sometimes prove cheaper using this method.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Washington Dulles Airport to St. Louis?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to St. Louis from Washington Dulles Airport up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

KAYAK’s top tips for finding a cheap flight from Washington, D.C. Dulles Intl Airport to St. Louis

  • Looking for a cheap flight? 25% of our users found flights on this route for $149 or less one-way and $335 or less round-trip.

Prefer to fly direct from Washington Dulles Airport to St. Louis?

 
Direct data is based off flight results for the next 60 days. Find direct flights from all airlines flying direct from Washington, D.C. Dulles Intl to Lambert-St Louis.
Find which airlines fly direct from Washington, D.C. Dulles Intl Airport to Lambert-St Louis Airport, which days they fly and book direct flights.

Direct departures

Washington, D.C. Dulles Intl to Lambert-St Louis

Monday

United Airlines

United Airlines

Tuesday

United Airlines

United Airlines

Wednesday

United Airlines

United Airlines

Thursday

United Airlines

United Airlines

Friday

United Airlines

United Airlines

Saturday

United Airlines

United Airlines

Sunday

United Airlines

United Airlines

See more direct flights

Direct returns

Lambert-St Louis to Washington, D.C. Dulles Intl

Monday

United Airlines

United Airlines

Tuesday

United Airlines

United Airlines

Wednesday

United Airlines

United Airlines

Thursday

United Airlines

United Airlines

Friday

United Airlines

United Airlines

Saturday

United Airlines

United Airlines

Sunday

United Airlines

United Airlines

See more direct flights

Reviews of the top 4 airlines serving from Dulles Intl to St. Louis

 
See real verified KAYAK customer reviews for airlines flying from Washington, D.C. to St. Louis. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Dulles Intl to St. Louis? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
7.9
DeltaOverall score based on 7998 reviews
8.5Crew
7.9Comfort
7.3Food
8.2Boarding
7.9Entertainment
Airline reviews

Staff were friendly and happy. Delta could make sure passengers that don't have the app know of changes. Without Kayak I would not have known about the change of gate or the delay. Kayak was faster to notify me.

8.0 ExcellentJulie, Oct 2025LAX - SFO
Read more Delta reviews

Staff were friendly and happy. Delta could make sure passengers that don't have the app know of changes. Without Kayak I would not have known about the change of gate or the delay. Kayak was faster to notify me.

They ended up paying for the bag twice, but the counter wouldn't take my baggage receipt. Left it to me to resolve. Not sure how to resolve the issue.

The customer service before board was very rude and when I expressed my concerns about making the connecting flight she laughed and told me I bought the wrong ticket. I explained once it showed the flight was delayed it no longer let me change seats or anything. I was trying to upgrade to make sure I would get to the next gate on time.

Non stop on long haul is the way to go. Great experience

The flight used a B767 with a very old interior from before 2014. The entertainment system did not work at all during the flight despite attempts to reset the system. It was like they flew this route just to be competitive.

They changed planes and the new plane couldn’t carry enough fuel to fly across the country so we had to stop in Kansas City to refuel. Flight was delayed .

Flight was too crowded and seats are too small, especially since passengrs are getting larger. Having a middle seat is ALWAYS tough! Woman on my left was large & kept creeping in to my space. Flight personnel were great! Have more savory rather than sweet snacks please.

Flight was crowded and the woman sitting on my left was large & kept crouching in to my space. You need bigger seats or smaller passengers to fit into the seats you DO have! Snack were OK. Would appreciate if airlines had more savory rather than sweet snacks, thank you!

Delayed flight (1hour) plus a long layover after an overnight flight with no backup plane available.

We were delayed, which I think had to do with air traffic control. Otherwise, everything was great.

Excellent flight. Smooth, efficient boarding. Quick flight. Arrived early at STL.

During booking, I kept trying submitting my payment from the Mexican website and it didn't work. After I had the idea to change it to the Canadian website, it worked but I had to be charged the equivalent of 50 CAD more. I received the clear instruction that I would only be able to check-in at the airport and that it was impossible to select a seat 24 hours before departure, that I had to pay 144 CAD to do so, although not only was I able to check-in 24 hours before departure, but I could have selected my seats for free then. All in all, I almost threw $200 out the window due to misleading information. Besides, the app kept crashing, the information to get to the gate on the app was inaccurate, my gate was switched and I was only informed once in the air (luckily I had noticed the departure pannel), I was not addressed in my language beforehand and even if I tried I was immediately answered in English (which meant the crew understood but didn't want to answer accordingly), there was only one snack & beverage service on my medium haul flight and no beverage service on my short haul flight. To be fair, the planes were comfortable, the crew apart from the language issue was helpful, dynamic and engaging, the plane was clean and the directions were clear and direct. United has a lot of potential to be one of my favourite airlines, but the devil is in the details and a lot of them missed the target.

Better WiFi. I cannot understand that in 2025, United is so behind on a technology that is now a necessity and still painfully unreliable, slow and keeps disconnecting.

Great service on board. Boarding a bit slow due to process. Food was pretty average.

Very small cramped plane for an international flight. Everything else was good, but it was maybe the smallest comfort-wise I've ever been on for longer than 3-4 hours and the trip was 7.5

Flight was delayed 3 hours. No food and drink vouchers was provided. They offered a mini pretzel bag and water .

Staff was rude. Didn’t give water for 2 hours. Worst service

Was on time until within 1 hour of flight-how does that happen? Staff very friendly.

I liked the choice of lemon ginger tea. I think stewardesses can be more considerate of older people needs.

We were given vouchers we couldn’t use with a 5.5 hour delay

The flight attendant, a black woman with curly hair who sat near Row 21, was wonderful and kind.

It took way too long to diagnose and solve the problem of a broken crew member cabin seat. Though compensation for the volunteer who left the flight was very kind.

We fly American Airlines quite a bit. And we always fly business class when traveling internationally. We were a bit disappointed with the comfort of this particular plane as well as the entertainment options.

The AA staff person who checked our bags was curt and almost rude. The FA also seemed unhappy doing her job. Overall it was like riding the school bus back in grade school.

They are still charging me after taking 466 and 833 for round trip from AR to to Bradley airport from 19 to 21. Then poor experience. Am hurt and I will say it on social media. Please stay away from this airline. I see in my bank account they are still taking 644. Am trying to stop it. I used to fly United airlines and I suggest that if you don't want extra charges and good service you go back there. American airlines delayed my flight again and I was late for my meeting, no recompensation but charging me over and over.

They changed our Gate 5 times, and concourse twice. Changed our seats twice.

Pitch was very small. Knees were on the seat back in front of me.

Wonderful as usual except for other guests that were unruly and not kept in check by the Crew.

The flight was initially delayed, then cancelled. American Airlines says the cancellation was weather related, though the actual weather was not bad in both Washington and Providence and between. There were very few cancellations that day. In fact, AA2120 from Washington, DC to Boston flew with a minor delay at about the same time. So, the weather somehow affected only this particular flight AA5230. The next available flight was the following morning. The American Airlines refused to reimburse accommodation (hotel at DCA)

Fine. On time, cabin service was fine, bag arrived. All good. Flying into DCA so did not collide with any helicopters, which is also good. Horrid incident that could have and should have been prevented.

Terrible. The canceled my entire flight when I requested a refund for a trip frontier canceled trip one way.

Boarding was on time and plane departed as scheduled. There are obviously no amenities (food, drink, entertainment) on Frontier, but there also didn't seem to be any issues with luggage space either.

Inbound plane was on time and flight departed on time with no issues while boarding.

I knew going into this that Frontier, being a low cost carrier, would be pretty bare bones and charge for most extras but this was made up for by the fact that the airplane was a reasonably new Airbus, every employee was great and best of all, Everett Washington is an amazing airport - thanks Frontier for flying there!!!

i was unable to check in the flight. refund requested

It was well done. It was my first time flying with them and I was nervous b/c I have heard of many cancelled and/or delray flights. Everything went smoothly.

Just know that everything, and I mean everything is “ala cart”. 60$ just to put something in the overhead bin. I will never fly Frontier again nor do I recommend them to anyone else.

The single worst check in experience I could imagine. I’ll never do any business with Frontier or any affiliated company

Too many extra fees, uncomfortable, little leg room. Will not recommend this airline.

Everyone seemed to be in zone 1 for boarding. Maybe break it up a little. Otherwise, smooth flight.

Everything you need to know for your flight from Dulles Intl to St. Louis

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