STL - IAD

$68 Find Cheap Flights from St. Louis to Washington Dulles Airport - Compare and Save

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 11/5. 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.
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Everything you should know

Cheapest round-trip
$259
Typical prices: $238-$483
Frontier
Sat 10/31Mon 11/2
STL - IAD • 1 stop
Cheapest non-stop
$287
Typical prices: $354-$805
United Airlines
Sat 9/5Wed 9/9
STL - IAD • Non-stop
Advice from real travelers
AI-powered summary based on content written by travel experts. AI can make mistakes.
Lufthansa Economy Flex adds free rebooking; good for flexible St. Louis-IAD trips.
United Economy Plus adds up to 6 inches more legroom; Priority Boarding helps.
Expert advice
Expert advice
Expert advice
Expert advice
Top airlines
Cheapest • from $259 (round-trip)
Best reviews • 7.8 score
Airline reviews
Airline reviews
+1
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Airline reviews
Airline reviews
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Nonstop flights
You can fly direct with United Airlines. Average duration is 2h 11m
Direct flights
Direct flights
+1
+1
Direct flights
Direct flights
+1
Top layover airports
Cheapest • Avg $296 (round-trip)
Shortest trip • 4h 26m (one-way)
Insights
Insights
Insights
Insights
When to travel
Cheapest • 55% price drop
Most popular
Good to know
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We hope you love your trip to Dulles Intl!
Flight Deals
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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

Sat, Oct 31 - Mon, Nov 2
Frontier Logo
10:35 am - 12:28 am
STL
-
IAD
12h 53m
1 stop
Frontier Logo
7:00 am - 5:54 pm
IAD
-
STL
11h 54m
2 stops
$259Frontier
Fri, Oct 30 - Mon, Nov 2
Frontier Logo
10:35 am - 12:28 am
STL
-
IAD
12h 53m
1 stop
Frontier Logo
7:00 am - 7:15 pm
IAD
-
STL
13h 15m
2 stops
$259Frontier
Thu, Sep 3 - Sun, Sep 6
United Airlines Logo
8:00 am - 1:55 pm
STL
-
IAD
4h 55m
1 stop
United Airlines Logo
10:35 am - 2:57 pm
IAD
-
STL
5h 22m
1 stop
$262United Airlines
Sat, Sep 5 - Mon, Sep 7
United Airlines Logo
8:30 am - 1:55 pm
STL
-
IAD
4h 25m
1 stop
United Airlines Logo
8:20 am - 12:02 pm
IAD
-
STL
4h 42m
1 stop
$262United Airlines
Tue, Sep 1 - Sun, Sep 6
Delta Logo
6:00 am - 2:05 pm
STL
-
IAD
7h 05m
1 stop
Delta Logo
11:10 am - 4:38 pm
IAD
-
STL
6h 28m
1 stop
$262Delta
Tue, Sep 8 - Fri, Sep 11
Delta Logo
6:00 am - 2:11 pm
STL
-
IAD
7h 11m
1 stop
Delta Logo
8:08 am - 12:32 pm
IAD
-
STL
5h 24m
1 stop
$262Delta
Fri, Aug 14 - Fri, Aug 21
Multiple Airlines Logo
2:00 pm - 2:02 pm
STL
-
IAD
23h 02m
2 stops
Multiple Airlines Logo
6:20 am - 5:22 pm
IAD
-
STL
12h 02m
1 stop
$290Multiple Airlines
Thu, Sep 3 - Sun, Sep 6
American Airlines Logo
6:54 am - 12:48 pm
STL
-
IAD
4h 54m
1 stop
American Airlines Logo
6:33 am - 11:56 am
IAD
-
STL
6h 23m
1 stop
$292American Airlines
Fri, Sep 25 - Mon, Sep 28
American Airlines Logo
10:21 am - 5:31 pm
STL
-
IAD
6h 10m
1 stop
American Airlines Logo
6:14 am - 9:29 am
IAD
-
STL
4h 15m
1 stop
$297American Airlines
Mon, Aug 10 - Thu, Aug 13
Multiple Airlines Logo
4:57 pm - 4:40 pm
STL
-
IAD
22h 43m
1 stop
Multiple Airlines Logo
2:56 pm - 1:31 pm
IAD
-
STL
23h 35m
2 stops
$518Multiple Airlines
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?

This analysis is based on the cheapest round-trip price found on KAYAK in the last 12 months by searching for a flight from St. Louis to Washington, D.C. Dulles Intl Airport departing in October.

Flight prices are below average for this route right now.

Flights to Washington, D.C. Dulles Intl Airport from St. Louis usually cost between $355 and $665 in October.
The lowest price found in the past 5 days was $259 on Frontier (Oct 10-Oct 12).

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 Wednesday and avoid Thursdays if you are looking for the best rates. For your return to St. Louis, you’ll find the best rates on Saturdays 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 February, where tickets cost $170 (return) on average. On the other hand, the most expensive months are August and June, where the average cost of round-trip tickets is $510 and $477 respectively.

Can I save money by flying with a layover from St. Louis to Washington, D.C. Dulles Intl Airport?

The average round-trip price for all non-stop flights, flights with one layover, and flights with two layovers for the route found by users searching on KAYAK in the last 2 weeks.

Yes, flying with a layover may cost you more time, but you can also save money on the route, with a 1 stop layover the cheapest option at $375 on average.

Expert advice

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

 
AI-powered summary based on content written by travel experts. AI can make mistakes.
KAYAK teamed up with top travel experts to share the best tips for your journey.
Our travel experts
Jessica Macdonald

Jessica Macdonald

Expert on Lufthansa

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.

Stefanie Waldek

Stefanie Waldek

Expert on United Airlines and IAD

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.

Yulia Denisyuk

Yulia Denisyuk

Expert on STL

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.

Good to know

Low season

February

Cheapest flight

$68
Best time to beat the crowds with an average 55% 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 5 days, the lowest price for a flight from St. Louis to Washington, D.C. Dulles Intl Airport was $68 for a one-way ticket and $259 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, Air Canada, 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 $343 and an overall rating of 7.8, Delta is the most popular choice. United Airlines is also a great choice for the route, with an average price of $464 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 $227 or less one-way and $687 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.
7.8
DeltaOverall score based on 8487 reviews
7.2Food
8.1Boarding
8.5Crew
7.8Entertainment
7.8Comfort
Airline reviews

Chaotic boarding at these gates, multiple gates squeezed in at the very end of a concourse, behind a restaurant. Agents gave up on boarding by individual zones. Flight itself was uneventful, which is all we hope for any more.

6.0 GoodAnonymous, Jul 2026
DTW - DCA
Read more Delta reviews

Chaotic boarding at these gates, multiple gates squeezed in at the very end of a concourse, behind a restaurant. Agents gave up on boarding by individual zones. Flight itself was uneventful, which is all we hope for any more.

Flight delayed due to ground hold. Republic airways did a great job.

From checking to boarding, it was a seamless experience. The service agents were so helpful. The flight crew was so pleasant.

The flight was smooth, the crew was great but the plane was quite old

Great flight with Delta! Boarding was quick and easy, the amenities were solid, and the plane was in great shape. The flight attendants had a fun, lively energy while staying professional. All in all, a smooth trip — even managed to catch up on some rest. Thanks, Delta!

My flight was canceled after being rescheduled for four days canceling my trip. Kayak and everyone affiliated with it I.e the airlines, and just fly have been excruciating to deal with. My trip to visit family had to be canceled as there was no way to make it. I am furious at all of you.

They delayed our flight because of bad weather in NY which was completely understandable. Then they cancelled our flight and a later flight that evening. The earliest we could fly was the next morning. We ended up buying last minute tickets on another airline and made it home slightly delayed but safely that evening. Delta kept saying it was weather related but if that was the case how did we make it back on another airline? The weather in NY was cloudy but not bad.

The plane smelled like a sewer. Multiple passengers complained. It’s a safety and quality issue to clean these planes.

1st flight had mechanical issues after we boarded and almost took off. They tried to fix on runway but couldn’t do we went back to the gate. They couldn’t fix it there either. So we had to deplane and board another plane 2 hrs later. All in all our flight was delayed 4 hrs so we had to cancel some business meeting we had in London for the morning since we were supposed to arrive at 7am and did not arrive until 11:45am. Also, the 2nd plane had mechanical issues as well but fortunately they were able to fix on runway.

We were delayed 2 hours leaving STL. I had 20 mins from when we landed in SLC terminal A to make it to SLC terminal B. I had to actually run! thankfully I made my flight but 3/4 legs were delayed to some capacity.

Our flight was great with an unexpected upgrade. However, four days into our travel we are still without a piece of luggage. The bag tracker has not been accurate, the airline is not communicating with me or the luggage delivery service and no one is willing to take responsibility or guarantee any kind of support or reimbursement. Unfortunately, we do not have the option to easily shop to replace items as we are currently on a cruise. I have been very disappointed by United Airlines response.

It was terribly delayed with zero support from united airlines. I reached at 1 am in the night. They did not provide any option to change the flights.

Flight was delayed 14 hours due to DC air show and weather. Missed connection to MUC.

Horrible I am at almost 2,000,000 miles on United. This was probably the worst flight ever. An hour and a half before takeoff I get a message that they’re changing the plane and I no longer have a seat in Polaris business Supposedly, there was a problem with the plane, but then there was no other plane Finally, they decided to bring a plane from Newark to Washington Dulles Of course the original flight was at 10:45 PM so by the time the plane got there it was 12:30 AM. It had not been cleaned. It had not been catered. They don’t really have people available to do those things when it’s not pre-programmed at 1 o’clock in the morning. The crew had to be changed And the new plane held 28 fewer people than the scheduled plane There is no way you can hate United Airlines enough The people at the gate were actually just fine, but it was management who was completely useless And did they send extra help to the people at the gate? Did they send supervisors? Of course not. Just don’t take United find somebody else or buy a boat

MY FAMILY'S LUGGAGE WAS LOST FROM ROME TO BARI. I WAS THE ONLY ONE THAT RECEIVED MY LUGGAGE FROM ROME TO BARI. AFTER DEPLANING IN BARI, WE WASTED A LOT OF TIME AT BAG CLAIMS LOST AND FOUND REPORTING THE CLAIM AND PLEADING FOR THE BAGS TO BE DELIVERED THE NEXT DAY. WE WERE TOLD THAT IT TAKES 3 DAYS MINIMUM TO DELIVER. MY DAUGHTER AND MY GIRLFRIEND NEEDED THEIR PERSONAL THINGS AND WE WERE STAYING 3 HOURS AWAY FROM THE BARI AIRPORT. WE HAD TO DRIVE 3 HOURS TO THE AIRPORT TO COLLECT OUR LOST LUGGAGE THE NEXT DAY. WE ARE NOT HAPPY WITH THE EXPERIENCE

Our flight to Rome, Italy was cancelled the day of and we were never informed. We only found out because I was trying to get into my husbands account and called to get his account number. Had to pay more for worse seating on another airline.

We were a little disappointed to not be able to complete check in online without uploading pics of passports. Also we have KTN's and they weren't on our boarding passes when we got to security. Had to trek back to counter to have them fix.

Excellent service in Polaris class IAD to ZRH. Arrived rested and well fed after the overnight flight.

It's a short hop. My carryon was checked at the gate, I didn't have to drag it all over the airport. Excellent wheelchair assist.

Fine not above and beyond as I had a connection that was delayed due to maintenance

My luggage was not sent with us. Not sure if this is Envoy Air responsibility but that was a very BAD experience

American delayed the flight for a crew rest period. The delay occurred late in the evening - the earliest i can find is 10:20 pm. With a 6 am flight anyone on the flight would have already have been asleep (unless you are insane, a vampire or on drugs) and at least for me i was already on the way to the airport at 445 am the next morning when i discovered they delayed the flight until 9 am. Given the incoming flight was in the air at 6 pm the evening before this should have been figured out a lot more timely that was there only crew to use. Just frustrating given there is no consideration for customer experience anymore in flying.

Good crew and flight was on time. It’s a small plane with limited overhead luggage space. They said the overhead space was full and I had to check my bag. There was still space when I got on. Waiting for my checked luggage added 30 minutes to my trip. Not the end of the world but also not great.

Trip delayed for 2 hours because of rain. We boarded and have to get down the flight and reboard again.

No enough space plus only allowing one laggage instead of two like other airlines.

Concern Regarding Significant Gate Delay and Jet Bridge Issue Dear Customer Relations Team, I am writing to express my disappointment with the experience I had on my recent flight AA 2414 on Sunday January 18, 2026. What should have been a routine departure turned into a frustrating and avoidable delay due to an issue with the jet bridge at the gate. As a result, the flight was delayed by approximately 90 minutes while multiple gate changes were attempted. The lack of clear communication during this period made the situation even more challenging. Passengers were left uncertain about the cause of the delay, the expected timeline, and the next steps. This not only disrupted travel plans but also created unnecessary stress for everyone on board. I understand that operational issues can arise, but a malfunctioning jet bridge and the resulting extended delay suggest an area where procedures or equipment maintenance may need attention. I hope you will review this incident to prevent similar disruptions in the future. I would appreciate acknowledgment of this concern and consideration of appropriate compensation for the inconvenience and lost time caused by this delay. Thank you for taking the time to review my experience. I look forward to hearing from you. Sincerely, Dion Dillard

Qatar airways ,boarding arrangements at Hamid international airport could been better

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.

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

Overall boarding and debarking is a joke. I dont even bring luggage anymore on trips because you can never allow them to be place then in the overhead bin or you have to pay or you check them which is even worse having to wait for your luggage on the tarmac.

Great except upon arrival it took them a long time to open the doors

Frontier feels like a family I Worked for Eastern Airlines back in the day and I felt the family vibe that I had then. Thank you

Terrible. Delayed my family flight for several hours affecting family plans

Tiny seats, no entertainment, no amenities, delays, they charge for carry on and their allowed personal item is smaller than in other airlines.

The seats are tiny and they don’t recline. The planes are dirty and very small. You have to pay for carry on and even the personal item that you’re allowed is smaller than with other airlines. Flights are usually delayed and there’s no screens or any amenities or entertainment.

Crew was kind of grumpy and there was no beverage service at all. Sodas were $4. Disappointing.

There's no seats that lean back with little leg space i wad uncomfortable the entire flight. Your charges for extra baggage is despicable and costly!!

There was no food and no entertainment, so I'm not sure why these are even in the survey, as my understanding is frontier does not ever offer food without a few, not even a snack, and there are no screens so unless the flight safety talk is our entertainment why ask how we liked it?. One of the flight attendants say in the back of the plane as people filed in to their seats, yelling orders about where to put baggage and telling people to hurry up. It was the least professional experience I've ever had on a flight.

The worst. We never made our connection and they did absolutely nothing to help us at the airport.

I have come to accept Frontier as an absolute no-frills airline, paying for everything I want. A 4.5-hour flight should provide me with a complimentary beverage—rather, $4.9x for a soda. Or a bottle of water ought to be extended at no cost. 4 beers are on the menu, but only 1 type of beer is available (at $9.95). Also, so many restrictions to using a voucher from Barclay‘s Credit Card. Finally, try to reach a live agent for Frontier- impossible!

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

Information on your arrival and departure airports