STL - IAD

$86 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 7/6. 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
$263
Typical prices: $731-$296
Frontier
Mon 7/6Wed 7/8
STL - IAD • 1 stop
Cheapest non-stop
$267
Typical prices: $805-$354
United Airlines
Tue 9/1Wed 9/2
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 $263 (round-trip)
Best reviews • 7.9 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 12m
Direct flights
Direct flights
+1
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Direct flights
Direct flights
+1
Top layover airports
Cheapest • Avg $281 (round-trip)
Shortest trip • 4h 24m (one-way)
Insights
Insights
Insights
Insights
When to book
in advance
Our data shows that travelers who book at least 3 weeks in advance save around 46% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
Cheapest • 53% price drop
Most popular
Good to know
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+1
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We hope you love your trip to Dulles Intl!
Flight Deals
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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

Mon, Jul 6 - Wed, Jul 8
Frontier Logo
4:09 pm - 12:47 pm
STL
-
IAD
19h 38m
1 stop
Frontier Logo
11:11 am - 11:59 pm
IAD
-
STL
13h 48m
1 stop
$263Frontier
Tue, Aug 11 - Mon, Aug 17
Delta Logo
10:33 am - 4:38 pm
STL
-
IAD
5h 05m
1 stop
Delta Logo
8:28 am - 11:46 am
IAD
-
STL
4h 18m
1 stop
$264Delta
Sat, Sep 26 - Mon, Sep 28
Delta Logo
6:40 am - 11:33 am
STL
-
IAD
3h 53m
1 stop
Delta Logo
3:13 pm - 7:44 pm
IAD
-
STL
5h 31m
1 stop
$265Delta
Mon, Aug 17 - Wed, Aug 19
American Airlines Logo
3:25 pm - 10:55 pm
STL
-
IAD
6h 30m
1 stop
American Airlines Logo
1:23 pm - 4:25 pm
IAD
-
STL
4h 02m
1 stop
$266American Airlines
Wed, Jul 1 - Wed, Jul 8
Delta Logo
10:51 am - 4:50 pm
STL
-
IAD
4h 59m
1 stop
Delta Logo
5:26 pm - 8:37 pm
IAD
-
STL
4h 11m
1 stop
$267Delta
Thu, Jul 16 - Mon, Jul 20
Frontier Logo
4:09 pm - 6:33 pm
STL
-
IAD
25h 24m
1 stop
Frontier Logo
9:50 am - 6:15 pm
IAD
-
STL
9h 25m
1 stop
$268Frontier
Sun, Jul 12 - Sun, Jul 19
Frontier Logo
6:34 pm - 5:14 pm
STL
-
IAD
21h 40m
1 stop
Frontier Logo
8:33 pm - 8:57 am
IAD
-
STL
13h 24m
1 stop
$269Frontier
Sat, Aug 1 - Sun, Aug 9
Frontier Logo
7:10 pm - 8:20 am
STL
-
IAD
12h 10m
1 stop
Frontier Logo
9:50 am - 6:15 pm
IAD
-
STL
9h 25m
1 stop
$270Frontier
Thu, Sep 24 - Mon, Sep 28
Delta Logo
10:00 am - 6:21 pm
STL
-
IAD
7h 21m
1 stop
Delta Logo
3:13 pm - 7:44 pm
IAD
-
STL
5h 31m
1 stop
$271Delta
Fri, Jul 10 - Sun, Jul 12
Frontier Logo
4:57 pm - 10:55 pm
STL
-
IAD
4h 58m
1 stop
Frontier Logo
7:49 am - 5:37 pm
IAD
-
STL
10h 48m
1 stop
$273Frontier
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 July.

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 Tuesday 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 July and June, where the average cost of round-trip tickets is $489 and $445 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 $363 on average.

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 3 weeks before departure, which saves you about 46% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 15 weeks before departure.

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 seasonFebruary
Cheapest flight$86
Best time to beat the crowds with an average 54% drop in price.
Most popular time to fly with an average 12% 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 $86 for a one-way ticket and $263 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 $338 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 $468 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 $223 or less one-way and $1,055 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 8400 reviews
7.2Food
8.1Boarding
8.5Crew
7.8Comfort
7.8Entertainment
Airline reviews

Five hour delays every hour, I wish it were all at once

2.0 MediocreAnonymous, Jun 2026
MCO - LGA
Read more Delta reviews

Five hour delays every hour, I wish it were all at once

Flight delayed four separate times. I’m now one hour hours late to landing.

worst flight ever from Delta, it got delayed and kept on delaying..

Should never have had to go to Detroit from Orlando back to Tennessee!

Got rerouted from a straight flight from Orlando to Atlanta to Knoxville to a flight from Orlando to Detroit to Knoxville! Seriously!! Flight delay out of Detroit! Long day for what should have been a pretty easy travel day!

Two delays on two separate planes with parts they could not easily find and replace.

Checkin was good, fllight ws good. Onlly complaint is lack of foot on 6 hour flight from Seattle to Boston. Snacks were flimsy - chips and cookies. could have offered something more substantial for such a long flight. I know you can buy food in airport but for the price you pay for a ticket, they should step up for the passengers.

Only beverages were offered to first class and I thought the flight attendant could have also served the Delta Comfort as well instead of sitting down and staring at her phone and walking past all of us to the back of the plane to charge her phone more. There was a complete lack of turbulence and was safe enough for flights attendant to walk around in the front of the plane, collect trash and serve a few people water and turn off the seat belt light. Also didn’t enforce people putting their seats into the upright position and allowed two passengers to remain reclined during landing. They seemed out to lunch completely. Usually my experience on Delta is much better.

Long story short, it was one of the better flight experiences I've had in some time when compared with other airlines.

Flight was great! This flight from Atlanta was even better than when I paid for Comfort from SNA to Atlanta.

Our flight was delayed 2.5 hours from Lisbon to DC so we missed our connection to Seattle that would have arrived at about 9 PM. The agent initially said we had to stay overnight in DC and there were no other options to put us on to get us to Seattle. While on board I discovered a flight via American he could have put us in but by the time we arrived in DC that was sold out. We were then put on a flight to San Francisco that was also delayed then arrived in San Francisco and our flight to Seattle was also delayed so we ended up not arriving until 2:15 am. Our son could not pick us up so we ended up having to pay over $100 to Uber home. This is the second trip with United that the flight has been delayed causing us to miss an evening in Las Vegas and we were given nothing.

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

There were no facilities in the middle of the aircraft and premium economy was not allowed to use the business class facilities, and had to share the only two toilets at the back with economy. The upgrade to Premium was definitely not worth it

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.

The economy seat was much less comfortable for an international flight in terms of recline and moving space when food tray is expanded. Per entertainment, it would be amazing if I could connect my Bluetooth headset or ear phones to the entertainment screen. Or provide in-flight wifi to connect directly from my own device.

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.

Was great in general, try to respect time and excuses when slight changes have been made, appreciated!

Terrific in every way. On time, professional staff, multiple movie options to select, great food and drink.

The airplane was an old model, the overhead didn’t have enough room for people’s items and made boarding and boarding disappointing and stressful. Crew allowed passengers to bring more than the permitted baggage sizes.

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.

It was great. Smooth flight, comfortable, left on time and landed on time.

Horrible experience upon landing. Probably more due to DCA utter incompetence than AA.

Easy boarding. Rows are smaller but that may be an older and bigger me now :)

Flight has been delayed every time I've ever taken it. Seats uncomfortable. Children behind me yelling the entire flight. Some of this is out of their control but overall just consistently not a great experience.

Poor communication ahead of time about flight delays and old planes/other equipment.

Never going to fly your airline again if it can be avoided.

Not to have gotten delayed by 2+ hours for the fourth straight American flight. They're the worst.

Other than nearly three hour delay for maintenance issues, everything went smooth

There weren't enough employees at check in took awhile to get bags checked. There wasn't a wheel chair for me, I was sent to someone who turns out to work for a different airline, if My flight hadn't been delayed I probably would have missed my flight as it was, by the time I arrived at my gate, they started boarding in about 15 minutes. I don't know who took me to my gate, definitely was not the normal people who take passengers to the gate. I'm guessing she may have been in a management position. I wish I knew her name, she went beyond to help me. With that said everyone was kind, and were doing the best they could. So, I choose to say it was an Adventure, stressful start, but good. In the end went well. The situation was not only difficult for passengers but the employee's.

The staff at the check in counter was so rude. Made you feel Incompetent

Frontier scheduled a 40 minute connection in DEN. What they failed to mention was that they “close the doors” 20 mins prior to departure, which means you only have 20 mins. Not enough time. Possibly against DOT regulations. Filing complaint.

Flight was scheduled at 9:40pm. Got delayed to 10 am, the next day. crazy

The bag check, flight check-in, and onboard experience convinced my wife and me that we will actively go out of our way to avoid flying Frontier Airlines in the future. At bag check, we were informed that check-in could only be completed via the Frontier mobile app. Unfortunately, the app was extremely frustrating—sending us through repetitive, confusing loops that repeatedly forced us to decline add-on services with nearly every click. While most airline apps upsell, this one felt intentionally exhausting. As the process dragged on, we became genuinely concerned that my phone battery would die before check-in could be completed. We approached the bag check staff—who were standing together talking—and explained both our frustration and our predicament. They laughed. Later, my wife described the interaction as “gaslighting,” which felt accurate. We were then informed it would cost $25 per person simply to have our boarding passes printed. From that point forward, the tone of the experience was consistently hostile. The bag check employees were condescending and combative, behaving more like bullies than customer service staff. Unfortunately, that same attitude continued onboard. One flight attendant argued with me when I attempted to stow my backpack in the overhead bin. I explained that we had each paid $75 to check our bags specifically so we would not need to use carry-on space and could have adequate legroom. She demanded to see my ticket, pointed out that it said “no carry-on”—which I acknowledged—and I reiterated that this was precisely why we paid to check our bags. Her response was, “I don’t make the rules.” She then walked away, but not before asking if I “truly wanted to fly back to Chicago today?”—an unnecessary and unmistakable threat. It is also worth noting that despite booking our tickets together in the same transaction, we were not seated together. Upon our return to Chicago—where we could once again sit together—we compared onboard experiences. We both remarked on how unhappy the flight attendants appeared and how each of us was separately asked whether we would like to purchase a beverage. We declined. At no point was water mentioned as an option, leaving us with the clear impression that even water came at a cost—or that complimentary water, if available at all, was deliberately left unmentioned. Overall, the experience was shocking and deeply disappointing, but it was also a profound learning experience—one we will not forget and will not repeat. -Steve

Plane was hot and miserable and the crew was rude!

12 hour delay required getting on and off plane 3 times - would have at least liked to have been offered a snack or drink

They didn’t offer a water, even after I asked

They switched our terminal 3 times and we were delayed for four plus hours!!!

It was an early flight and most people napped/slept and the crew let us which was nice.

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

Information on your arrival and departure airports