STL - IAD

$72 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 10/30. 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

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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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

Fri, Oct 10 - Sat, Oct 11
Frontier Logo
11:32 am - 11:29 pmSTL-IAD
10h 57m1 stop
Frontier Logo
4:22 pm - 9:22 amIAD-STL
18h 00m2 stops
$186Frontier
Find Deal
Fri, Dec 5 - Sun, Dec 7
Frontier Logo
6:26 pm - 12:19 amSTL-IAD
4h 53m1 stop
Frontier Logo
6:00 am - 5:31 pmIAD-STL
12h 31m1 stop
$189Frontier
Find Deal
Thu, Nov 13 - Sun, Nov 16
Frontier Logo
11:07 am - 4:34 pmSTL-IAD
4h 27m1 stop
Frontier Logo
6:00 am - 10:12 amIAD-STL
5h 12m1 stop
$192Frontier
Find Deal
Mon, Nov 10 - Tue, Nov 18
Delta Logo
6:09 pm - 11:03 pmSTL-IAD
3h 54m1 stop
Delta Logo
12:36 pm - 4:07 pmIAD-STL
4h 31m1 stop
$197Delta
Find Deal
Mon, Sep 29 - Sat, Oct 4
Frontier Logo
4:00 pm - 12:15 amSTL-IAD
7h 15m1 stop
Frontier Logo
7:14 pm - 1:02 pmIAD-STL
18h 48m1 stop
$199Frontier
Find Deal
Sun, Oct 5 - Sun, Oct 12
United Airlines Logo
8:05 am - 11:15 amSTL-IAD
2h 10mnonstop
United Airlines Logo
6:30 am - 10:49 amIAD-STL
5h 19m1 stop
$212United Airlines
Find Deal
Wed, Nov 12 - Fri, Nov 14
United Airlines Logo
8:25 am - 11:33 amSTL-IAD
2h 08mnonstop
United Airlines Logo
5:33 pm - 11:44 pmIAD-STL
7h 11m1 stop
$229United Airlines
Find Deal
Tue, Oct 14 - Wed, Oct 15
American Airlines Logo
12:51 pm - 6:54 pmSTL-IAD
5h 03m1 stop
American Airlines Logo
8:09 am - 12:06 pmIAD-STL
4h 57m1 stop
$276American Airlines
Find Deal
Fri, Nov 14 - Sun, Nov 23
Delta Logo
9:21 am - 5:04 pmSTL-IAD
6h 43m1 stop
Delta Logo
7:01 am - 1:00 pmIAD-STL
6h 59m1 stop
$277Delta
Find Deal
Thu, Feb 19 - Sat, Feb 21
American Airlines Logo
7:30 am - 12:41 pmSTL-IAD
4h 11m1 stop
American Airlines Logo
2:06 pm - 5:13 pmIAD-STL
4h 07m1 stop
$283American Airlines
Find Deal

Everything you should know

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 $186 (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 43% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
March
Cheapest • 20% price drop
November
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
Cheapest round-trip
$186
Typical prices: $271-634
Frontier
Fri 10/10Sat 10/11
STL - IAD • 1 stop
Cheapest non-stop
$246
Typical prices: $504-693
United Airlines
Sun 10/5Sun 10/12
STL - IAD • Non-stop
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!
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
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.

How much is a round-trip flight from St. Louis to Washington, D.C. Dulles Intl Airport?

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 October, where the average cost of round-trip tickets is $501 and $475 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 43% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 14 weeks before departure.

Good to know

Low seasonMarch
Cheapest flight$72
Best time to beat the crowds with an average 21% drop in price.
Most popular time to fly and prices are also 19% lower on average.
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 $72 for a one-way ticket and $186 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?

    Star Alliance is the only airline alliance operating flights between St. Louis and Washington Dulles Airport.

  • 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 $265 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 $444 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 $355 or less one-way and $613 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 3 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 7954 reviews
8.5Crew
7.9Comfort
7.9Entertainment
8.2Boarding
7.3Food
Airline reviews

Perfect flight both ways. On time, courteous staff, plane comfortable and cool. Best domestic flights I’ve had in awhile.

10.0 ExcellentAnonymous, Sep 2025CLT - BOS
Read more Delta reviews

Perfect flight both ways. On time, courteous staff, plane comfortable and cool. Best domestic flights I’ve had in awhile.

Really low quality food especially for an international flight. The crew also was surprisingly unpleasant except couple of ladies. I know we were not in first class but that’s no reason to treat customers as less.

Flight delayed for two and half hours and then canceled altogether due to mechanical issues. No mechanic onsite to fix so had to send one from LAX.

Crew was good. The reservation got mixed up and they didn't have my TSA number. I am also a Silver Medallion and wasn't able to use Sky Priority.

Delta made it easy, comfortable and timely. The crew was fantastic.

This route with Delta always has delays or is cancelled. Aircrafts seem smaller and older. I fly Delta quite a bit - haven’t had issues with the international flights. But this route has always been the troublesome one

Three seats in first class were broken and while they were able to still acommodate us it was looking very touch and go and they had others they could not acommodate

Mechanic delay in addition to a 2 hour change in takeoff time was frustrating.

Delayed due to thunderstorms and no in-flight service due to rough weather — both of which are out of Delta’s control. Flight was good overall.

The flight attendants in SLC were rude. I arrived 40 minutes early to gate. Ticket said I needed check in for seat assignments and tried check in and attendants said they weren’t doing it. And proceeded to never call me to give me a ticket so when time to board I received the very last seat. Please relay to employees to do their job better..,

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

United airlines, mediocre at best. No issues , nothing great . Worked for me

Turbulent taking off & landing to Dulles from Raleigh. Flight from Dulles to Tokyo very good!!

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

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

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