STL - IAD

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

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from St. Louis to Dulles Intl departing on 11/13. 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 Washington, D.C. Dulles Intl Airport

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

Cheapest round-trip
$200
Overall average: $330
Frontier
Sun 12/21Wed 12/24
STL - IAD • 1 stop
Cheapest non-stop
$261
Typical prices: $266-$520
United Airlines
Thu 1/15Sun 1/18
STL - IAD • Non-stop
Our travelers' advice
AI-generated summary based on content written by travel experts
United's Economy Plus offers extra legroom for comfort.
Use the Silver Line Metro for easy access to downtown D.C.
Expert advice
Expert advice
Expert advice
Expert advice
Top airlines
Frontier
Cheapest • from $200 (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 42% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
March
Cheapest • 20% price drop
October
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
Start a new search
KAYAK searches 100s of sites at once to find you the best travel deals.
We hope you love your trip to Dulles Intl!
Flight Deals
Booking Insights
Expert advice
Flight Deals

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

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from St. Louis to Dulles Intl 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 St. Louis to Dulles Intl

Sun, Dec 21 - Wed, Dec 24
Frontier Logo
10:57 am - 4:58 pmSTL-IAD
5h 01m1 stop
Frontier Logo
7:01 pm - 9:40 amIAD-STL
15h 39m1 stop
$200Frontier
Find Deal
Sat, Dec 20 - Wed, Dec 24
Frontier Logo
4:27 pm - 9:03 pmSTL-IAD
27h 36m1 stop
Frontier Logo
7:01 pm - 9:40 amIAD-STL
15h 39m1 stop
$201Frontier
Find Deal
Thu, Dec 11 - Sun, Dec 14
Frontier Logo
12:04 pm - 6:18 pmSTL-IAD
5h 14m1 stop
Frontier Logo
5:45 am - 9:47 amIAD-STL
5h 02m1 stop
$202Frontier
Find Deal
Sun, Dec 21 - Sat, Dec 27
Frontier Logo
4:27 pm - 11:38 amSTL-IAD
18h 11m2 stops
Frontier Logo
7:11 pm - 9:40 amIAD-STL
15h 29m1 stop
$203Frontier
Find Deal
Fri, Nov 14 - Tue, Nov 18
Frontier Logo
4:56 pm - 12:11 amSTL-IAD
6h 15m1 stop
Frontier Logo
8:40 am - 9:07 amIAD-STL
25h 27m2 stops
$207Frontier
Find Deal
Tue, Dec 23 - Mon, Dec 29
Multiple Airlines Logo
10:48 am - 4:37 pmSTL-IAD
4h 49m1 stop
Multiple Airlines Logo
7:06 pm - 10:56 amIAD-STL
16h 50m2 stops
$223Multiple Airlines
Find Deal
Wed, Dec 10 - Thu, Dec 11
United Airlines Logo
8:30 am - 11:40 amSTL-IAD
2h 10mnonstop
United Airlines Logo
8:40 am - 10:07 amIAD-STL
2h 27mnonstop
$272United Airlines
Find Deal
Wed, Dec 3 - Sat, Dec 6
United Airlines Logo
8:30 am - 11:40 amSTL-IAD
2h 10mnonstop
United Airlines Logo
5:19 pm - 11:44 pmIAD-STL
7h 25m1 stop
$273United Airlines
Find Deal
Wed, Dec 3 - Sat, Dec 6
United Airlines Logo
8:30 am - 11:40 amSTL-IAD
2h 10mnonstop
United Airlines Logo
8:40 am - 10:07 amIAD-STL
2h 27mnonstop
$274United Airlines
Find Deal
Tue, Dec 9 - Thu, Dec 11
United Airlines Logo
8:30 am - 11:40 amSTL-IAD
2h 10mnonstop
United Airlines Logo
8:40 am - 10:07 amIAD-STL
2h 27mnonstop
$275United Airlines
Find Deal
Booking Insights

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

Get data-powered insights and trends into flights from St. Louis to Dulles Intl 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 St. Louis to Washington Dulles Airport?

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

When flying from St. Louis to Washington Dulles Airport, you should consider leaving on a Friday and avoid Saturdays if you are looking for the best rates. For your return to St. Louis, you’ll find the best rates on Wednesdays and the most expensive ones on Mondays.

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

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from St. Louis to Washington, D.C. Dulles Intl Airport, 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 St. Louis to Washington, D.C. Dulles Intl Airport is March, where tickets cost $300 (return) on average. On the other hand, the most expensive months are July and February, where the average cost of round-trip tickets is $489 and $453 respectively.

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

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from St. Louis to Washington, D.C. Dulles Intl Airport, 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 St. Louis to Washington, D.C. Dulles Intl Airport, you should book around 4 weeks before departure, which saves you about 42% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 14 weeks before departure.

Expert advice

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

 
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.
Airlines
Lufthansa

Lufthansa's Economy Flex allows free rebooking, ideal for flexible travel plans.


Lufthansa offers FlyNet Messaging for free to Miles & More members on short-haul flights.

Read more about Lufthansaby Jessica Macdonald
United Airlines

United offers Priority Boarding to avoid gate-checking carry-ons, ideal for quick boarding.


United's Economy Plus seats offer up to six inches more legroom than standard economy.

Airports
STL

Avoid peak hours at STL to minimize wait times. Early mornings and afternoons can be particularly crowded.

Read more about STLby Yulia Denisyuk
IAD

Use the Silver Line Metro for a convenient 50-minute ride from IAD to downtown D.C. It's cost-effective and avoids traffic.

Read more about IADby Stefanie Waldek
Our travel experts
Jessica Macdonald

Jessica Macdonald

Expert on Lufthansa

Jessica Macdonald

Jessica Macdonald

Currently based in Scotland after living in South Africa and the United States, Jessica has been writing travel and aviation content for more than 10 years. She regularly contributes to Travel + Leisure and TripSavvy, and has had work published by Condé Nast Traveller and The Independent. She has traveled to more than 50 countries across six continents.

Read more
Stefanie Waldek

Stefanie Waldek

Expert on United Airlines and 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
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

Good to know

Low seasonMarch
Cheapest flight$55
Best time to beat the crowds with an average 20% drop in price.
Most popular time to fly with an average 9% increase in price.
Flight from St. Louis to Washington Dulles Airport

When to book flights from St. Louis to Dulles Intl

Are your dates flexible? Find out the best times to travel from St. Louis to Dulles Intl 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 St. Louis to Washington Dulles Airport flights

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

    In the last 3 days, the lowest price for a flight from St. Louis to Washington, D.C. Dulles Intl Airport was $55 for a one-way ticket and $200 for a round-trip.

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

    No

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

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

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

    Lufthansa, American Airlines, Delta, and United Airlines offer inflight Wi-Fi service on the St. Louis to Washington Dulles Airport flight route.

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

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

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

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

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

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

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

    The two airlines most popular with KAYAK users for flights from St. Louis to Washington, D.C. are Delta and United Airlines. With an average price for the route of $271 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 $426 and an overall rating of 7.4.

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

    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 St. Louis to Washington Dulles Airport.

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Washington Dulles Airport from St. Louis 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 St. Louis to Washington Dulles Airport?

    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 Washington Dulles Airport with an airline and back to St. Louis with another airline. Booking your flights between St. Louis and IAD 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 St. Louis to Washington Dulles Airport?

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

  • Looking for a cheap flight? 25% of our users found flights on this route for $298 or less one-way and $465 or less round-trip.

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

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

Direct departures

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

Direct returns

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

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

 
See real verified KAYAK customer reviews for airlines flying from St. Louis to Washington, D.C.. 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 St. Louis to Dulles Intl? 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 7992 reviews
7.9Comfort
8.2Boarding
7.3Food
7.9Entertainment
8.5Crew
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.

Crew was dismissive. Snacks and refills not offered. Poor business class experience. Bed not comfortable compared to Emirates or BA.

Flight was delayed for 5 hours because crew didn’t have enough time to rest - this seems like it could have been avoided with better scheduling. Food was not good.

IAD with the archaic people movers is just a place to be avoided.

Overall, it was good. I was seating next to a wonderful lady and did not notice how time flew. Thanks

This is the best united airlines flight that I took. The crew was very friendly and the food was tasty!

It is clear that someone knew, and competent, is in charge of food at United Airlines at least for the international flights. I was flying in coach, but the choices of the dinner were excellent. Tasty, and appropriate size. I had the beef, which was a little bit like a shepherds pie, and it was good. Nothing comparable has been served on a United flight in years. It will not be confused with three star food, but it is very good for airline food. Even better was the breakfast choice between a cinnamon roll and a breakfast sandwich. I chose the breakfast sandwich which was absolutely delicious and which I would happily order again at my local Starbucks or Panera. It is clear that someone knew indifferent is in charge of the food and it’s about time.

Had one staff that was not pleasant. Seems they are stressed with too many people to care for.

I would have liked an opportunity to move to a different seat ( even would have checked in my hand luggage)as I had health issues where I didn't have to clamber over the passenger next to me to for toilet use/ movement [ She was a highly unpleasant neighbor to sit next to]. In addition, I found that my European phone plan had run out of data and so I was not receiving emails from yourselves on airport wifi to be able to check in online and verifications difficult as did not accept the ticket number I had. I asked for an extra blanket but was told there was none. Then I saw other passengers receiving them. I couldn't eat the food and asked for snacks : Stewardess said " on the way" but they did not bring. The best bit was the check in process in Lisbon. Very efficient. However, I did not understand why we had to collect our bags at Washington then go through customs again. It was not explained. I also with my leg and health issue had approximately mile walk to the gate ( which then changed) . There appeared to be no moving walkways or help provided.

The attendant were friendly. I suggest you have a medical attendant on board every flight so that in case someone is sick , he/she will help them.

We had a very long diversion and our food voucher didn’t work because the restaurants were closed

After we'd boarded , they canceled the flight. The crew didn't even know , we just all received text messages. Then after they deplaned us , AA was just like "too bad, go F your self, we sure ain't gonna help you"

Initial flight was cancelled at the time of arrival to the airport, flight alternative requires switching from direct to flight with a layover, and the plane felt like it would split apart, it was so rattle-y.

Weather delay for 2.5 hours followed by half hour crew delay, did not have ginger ale, uncomfortable seats

It was nobody’s fault - but the plane came 4-hrs late and we were updated randomly in 20-30 mins increments which left us hostage to sit and wait expectantly. It was very long and got very late. Our plane didn’t land until nearly 1 am! Also the toilet wasn’t working. The hosts were nice enough but were clearly “about to pass out” as one told me. Lastly, there was no snack or even time for it. Just a bad experience overall.

The boarding crew was incredibly helpful getting me on an earlier flight

Two flight changes before the scheduled flight. On the day of the flight, the flight was delayed, which caused the connecting flight to be missed. Then, I was directed to another airport (CUN) and traveled to Tulum. American gave a $12 voucher for lunch. The least expensive item on the menu at a Mexican restaurant was $9.99. Driving to Tulum was a bad auto crash, and traffic was delayed two-plus hours. The bottom line is that we should have been at the hotel at noon, but it ended up at 11:30 PM.

Great experience. Flight boarded easily. Departed early. Smooth flight. Great arrival in DC--almost no taxing! Almost direct to gate from runway. Crew was terrific. Same cookies and beverages in main cabin. I did not use the entertainment system on this flight.

Flight delayed on both ends - have a gate ready at DCA, don't make us sit for 30min after being late to take off as well.

AA can't control the weather. But the airplane was hot and stuffy while stuck on the runway with a broken entertainment system.

Miami lounges were overcrowded and we were unable to get in. We only had a short time. But the banks are too tight in all American hubs

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 St. Louis to Dulles Intl

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