STL - IAD

$85 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 5/6. 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
Travelers love KAYAK
41.299.237 searches in the past 7 days on KAYAK

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Everything you should know

Cheapest round-trip
$246
Overall average: $374
Frontier
Fri 4/17Tue 4/21
STL - IAD • 1 stop
Cheapest non-stop
$265
Typical prices: $382-$623
United Airlines
Sat 4/11Sat 4/18
STL - IAD • Non-stop
Advice from real travelers
AI-powered summary based on content written by travel experts. AI can make mistakes.
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
Cheapest • from $246 (round-trip)
Best reviews • 7.9 score
Airline reviews
Airline reviews
+1
+1
Airline reviews
Airline reviews
+1
Nonstop flights
You can fly direct with United Airlines. Average duration is 2h 12m
Direct flights
Direct flights
+1
+1
Direct flights
Direct flights
+1
Top layover airports
Cheapest • Avg $276 (round-trip)
Shortest trip • 4h 23m (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 36% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
Cheapest • 55% price drop
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

Fri, Apr 17 - Tue, Apr 21
Frontier Logo
8:23 pm - 9:54 am
STL
-
IAD
12h 31m
1 stop
Frontier Logo
8:20 am - 11:19 pm
IAD
-
STL
15h 59m
2 stops
$246Frontier
Wed, Apr 8 - Sun, Apr 12
Frontier Logo
4:59 pm - 11:33 am
STL
-
IAD
17h 34m
1 stop
Frontier Logo
6:39 pm - 7:51 am
IAD
-
STL
14h 12m
1 stop
$247Frontier
Sun, Mar 29 - Wed, Apr 8
Frontier Logo
4:51 pm - 7:24 am
STL
-
IAD
13h 33m
1 stop
Frontier Logo
3:15 pm - 11:25 pm
IAD
-
STL
9h 10m
2 stops
$248Frontier
Thu, Apr 9 - Mon, Apr 13
Multiple Airlines Logo
6:29 pm - 4:49 pm
STL
-
IAD
21h 20m
1 stop
Multiple Airlines Logo
2:58 pm - 11:25 pm
IAD
-
STL
9h 27m
2 stops
$252Multiple Airlines
Fri, Apr 10 - Sun, Apr 12
Frontier Logo
4:59 pm - 10:11 am
STL
-
IAD
16h 12m
1 stop
Frontier Logo
6:00 am - 10:38 am
IAD
-
STL
5h 38m
1 stop
$255Frontier
Thu, May 7 - Sun, May 10
Frontier Logo
6:55 pm - 10:12 am
STL
-
IAD
14h 17m
1 stop
Frontier Logo
5:26 pm - 8:55 am
IAD
-
STL
16h 29m
1 stop
$256Frontier
Wed, Apr 8 - Wed, Apr 15
United Airlines Logo
6:30 am - 11:48 am
STL
-
IAD
4h 18m
1 stop
United Airlines Logo
8:20 am - 12:22 pm
IAD
-
STL
5h 02m
1 stop
$257United Airlines
Fri, Apr 17 - Sun, Apr 19
Frontier Logo
8:39 am - 7:24 pm
STL
-
IAD
9h 45m
1 stop
Frontier Logo
6:20 am - 6:50 am
IAD
-
STL
25h 30m
1 stop
$258Frontier
Thu, Apr 16 - Sun, Apr 19
Frontier Logo
11:25 am - 12:36 am
STL
-
IAD
12h 11m
1 stop
Frontier Logo
9:41 am - 6:50 am
IAD
-
STL
22h 09m
1 stop
$259Frontier
Thu, Apr 2 - Mon, Apr 6
Frontier Logo
6:29 pm - 12:36 am
STL
-
IAD
5h 07m
1 stop
Frontier Logo
10:25 pm - 10:30 am
IAD
-
STL
13h 05m
1 stop
$260Frontier
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 Thursdays 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 February, where tickets cost $170 (return) on average. On the other hand, the most expensive months are July and May, where the average cost of round-trip tickets is $569 and $459 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 $424 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 36% 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$85
Best time to beat the crowds with an average 55% drop in price.
Most popular time to fly with an average 21% 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 $85 for a one-way ticket and $246 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?

    American Airlines, Lufthansa, Delta, United Airlines, and Air Canada 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 $275 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 $465 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 $432 or less one-way and $491 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 8293 reviews
7.9Comfort
7.8Entertainment
8.5Crew
8.1Boarding
7.2Food
Airline reviews

We landed and sat on the tarmac for 45 minutes because they only have one gate at the airport and there was another plane running late so we had to wait

2.0 MediocreSusan, Mar 2026
JAX - ATL
Read more Delta reviews

We landed and sat on the tarmac for 45 minutes because they only have one gate at the airport and there was another plane running late so we had to wait

The WiFi was not working. That made for a long flight.

Absolutely no communication on why there's a delay and multiple flight time reschedules. I would have canceled the flight and drove back home if I known it was going to be rescheduled 3 or 4 times.

Another late night flight and MORE men belligerently drinking and yelling. I had to move from first to economy because they were so obnoxious and disruptive. Crazy to go from a cozy chair to cardboard when you were supposed to be in first. Delta allows was too much drinking which leads to belligerent behavior.

I was in first class and literally the men behind me were so aggressively loud I moved myself to economy. This has become so common on Delta - people using audio without headphones, and men on 12am / late night flights drinking and yelling to talk to each other which prevents anyone around them from resting. Pretty crazy to have to move from first to economy (poorer service, less comfort...). Wild wild. Looking into other airlines.

Love delta smaller commuter plane so no entertainment and paid wifi on MKE-LGA leg was extremely unreliable and slow

Stop changing gates. Stop cancelling flights Stop moving my seat.

Extremely disappointed with Delta. They canceled flight last minute and then I rebooked the other flights and with which were delayed as well

Could not get my connecting flight boarding pass until four hrs before departure! Ver annoying especially since the staff could not explain why!

The flight was flying with 30% capacity. The flight my seat from preferred seating to back of the seat. Even though i can understand that this was to balance the flight weight. The flight attendance decided to do the serving near my seat and in the middle , their noices woke me up from sleep , when i realized that the service has ended and when they were going back asked for a coffee, for which they answered they have completed teh service in my location. That really upset me as they woke me up and also rejected the coffee i asked. I ended up landing with a headache, thanks to the crew that screwed up my travel

It was okay, the food was good, but after the landing there was not enough time for luggage and security to catch a connection. It was crowded on board.

When I went to check in at the United counter in Barcelona, Spain I had 2 different menat 2 different times in United uniforms (standing around with a couple other employees) ask me if I was traveling alone. The one man asked me 3 different ways if I was traveling alone. I am, 68 yeaers old and have all my faculties. I thought it was weird and it made me feel very uncomfortable. What difference does it make if I was traveling alone or with someone? What if I was a recent widow? That would have been horrible. They never gave me a reason why they needed to know who I was traveling with. I was hesitant to question them because I needed to be on that flight.

Crew was great. 2 1/2 hour delay was due to staff needing "rest" was avoidable and self inflicted as United not willing to hire enough crew to keep flight on time.. Ridiculous. The crew and the passengers both suffered due to this.

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

Bad food, bad service, cold cabin with no additional blankets when asked for (they told me they don’t provide additional blankets). I’m a frequent traveler and this is one of the worst companies I traveled with (by the way I thought that I booked my ticket with Lufthansa but I didn’t see that the flights were handled by United).

Great other than a couple very drunk guys that for a while kept bumping my seat from behind. The staff did their best to control them. Even refused serving them alcohol and allowed the gal sitting next to them to move.

Good crew. Boarding delays. Almost two hours wait for the bags in DC.

Unfortunately weather delayed our flight waiting for our plane to arrive and due to a little snow time was needed to deice the plane so departure was very delayed and I missed the connecting flight

It was great. There were some issues prior to takeoff. The weather was poor so we had to go through deicing, and we were delayed a bit by the pilots' concern about one of the engines, but that's aviation. The pilots handled everything with aplomb, and kept us apprised

The seats were comfortable and we had leg room. Great entertainment.

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

Snow delayed boarding several times, which I understand happens. Issue I had was that after we did board, pilot told us we were going to roll out to be de-iced, then on our way. We were de-iced once, taxied to the tarmac and then stopped. Sat for another 30 minutes or so, the another de-icing. Then we rolled out to a parking spot, only to sit for another hour due to a traffic stop in DCA, which I'm confident they knew would happen before we boarded. Pilot gave no updates other than we had to hold, attendants did speak to the crew, but when asked, said the pilot would be updating us. We on the ground in the plane waiting for over 2 hours. They did communicate that bathrooms would be open, but no other news until we left. Would have been better to be up front about status.

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.

Flight was delayed. Not much information on when the flight would take off. Eventually we were told it was maintenance. App was not giving updates.

Flight was on time and there was an empty seat next to me. That makes for a good flight!

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!!

Remind customers of the need to have passport or new ID for boarding.

Flight was canceled. Most upsetting was message from Kayak, stating that the flight was canceled and click with Kayak for details regarding rebook, refund details. THERE'S NO INFORMATION PROVIDED BY KAYAK EXCEPT THAT FLIGHT IS CANCELED. AND NOW THIS SURVEY TO FIND OUT HOW WAS THE FLIGHT !!!!!!!

The flight never took off and we spent 7 hours at the airport

Gate not determined until I got to the airport - hard to plan the trip to the airport.

Our flight was canceled. I will never use Kayak nor Frontier for travel again. The entire experience was a headache.

Frontier.. nickel and dime add-ons. Flight late, on time, late again, last minute gate change, arrival gate required a shuttle to the terminal. They sure keep you guessing.. if you like a little chaos and airport anxiety, this is the airline for you!

This is my second time flying with Frontier. My current experience was very favorable. The staff from the gate to the plane was friendly, warm and professional. The food options lacked in my opinion. This area needs some attention in my opinion.

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.

Very well recently! Frontier is improving and less harrassing customer on luggages! Positive!

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

Information on your arrival and departure airports