STL - IAD

$63 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 5/20. 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
$254
Typical prices: $538-$198
Frontier
Mon 5/25Sat 5/30
STL - IAD • 1 stop
Cheapest non-stop
$265
Typical prices: $793-$491
United Airlines
Tue 5/19Sat 5/23
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 $254 (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 $282 (round-trip)
Shortest trip • 4h 20m (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 44% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
Cheapest • 54% price drop
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
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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

Mon, May 25 - Sat, May 30
Frontier Logo
5:27 pm - 10:12 am
STL
-
IAD
15h 45m
1 stop
Frontier Logo
1:26 pm - 7:31 pm
IAD
-
STL
7h 05m
1 stop
$254Frontier
Wed, May 20 - Fri, May 22
Frontier Logo
5:27 pm - 12:01 pm
STL
-
IAD
17h 34m
1 stop
Frontier Logo
7:45 am - 8:55 am
IAD
-
STL
26h 10m
1 stop
$255Frontier
Sat, Jun 6 - Thu, Jun 11
Frontier Logo
5:27 pm - 10:12 am
STL
-
IAD
15h 45m
1 stop
Frontier Logo
8:57 pm - 12:09 am
IAD
-
STL
28h 12m
2 stops
$256Frontier
Mon, May 25 - Sun, May 31
Frontier Logo
5:27 pm - 10:12 am
STL
-
IAD
15h 45m
1 stop
Frontier Logo
8:47 pm - 8:55 am
IAD
-
STL
13h 08m
1 stop
$257Frontier
Thu, Jul 9 - Sun, Jul 12
Frontier Logo
2:52 pm - 8:20 am
STL
-
IAD
16h 28m
1 stop
Frontier Logo
1:36 pm - 11:59 pm
IAD
-
STL
11h 23m
1 stop
$261Frontier
Fri, May 15 - Mon, May 18
Frontier Logo
5:27 pm - 10:12 am
STL
-
IAD
15h 45m
1 stop
Frontier Logo
6:17 pm - 5:33 pm
IAD
-
STL
24h 16m
1 stop
$262Frontier
Fri, May 22 - Fri, May 29
Multiple Airlines Logo
5:27 pm - 7:50 pm
STL
-
IAD
49h 23m
2 stops
Multiple Airlines Logo
8:47 pm - 8:55 am
IAD
-
STL
13h 08m
1 stop
$263Multiple Airlines
Tue, May 19 - Sat, May 23
United Airlines Logo
8:45 am - 11:55 am
STL
-
IAD
2h 10mnonstop
United Airlines Logo
5:55 pm - 7:26 pm
IAD
-
STL
2h 31mnonstop
$265United Airlines
Fri, May 15 - Mon, May 18
Frontier Logo
8:08 pm - 10:12 am
STL
-
IAD
13h 04m
2 stops
Frontier Logo
6:17 pm - 5:33 pm
IAD
-
STL
24h 16m
1 stop
$266Frontier
Sat, May 23 - Mon, May 25
Frontier Logo
5:27 pm - 10:12 am
STL
-
IAD
15h 45m
1 stop
Frontier Logo
1:31 pm - 2:48 pm
IAD
-
STL
26h 17m
1 stop
$267Frontier
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 May.

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 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 May, where the average cost of round-trip tickets is $489 and $421 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.

No, with an average price for the route of $476, prices are generally cheapest when you fly direct.

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 44% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 14 weeks before departure.

Expert advice

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

 
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$63
Best time to beat the crowds with an average 54% drop in price.
Most popular time to fly with an average 9% increase in price.
Flight from St. Louis to Washington Dulles Airport

When to book flights from St. Louis to Dulles Intl

Are your dates flexible? Find out the best times to travel from St. Louis to Dulles Intl based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking St. Louis to Washington Dulles Airport flights

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

    In the last 3 days, the lowest price for a flight from St. Louis to Washington, D.C. Dulles Intl Airport was $63 for a one-way ticket and $254 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, 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 $279 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 $455 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 $366 or less one-way and $596 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 8465 reviews
7.8Entertainment
8.1Boarding
7.9Comfort
8.5Crew
7.2Food
Airline reviews

The agent at check in and at the gate were less than thrilled to be at work. I'm not a fan of Kayak's placement on the plane. I got put in the middle seat and none of my preferences were used.

4.0 OkayBradley, Apr 2026
RDU - ATL
Read more Delta reviews

The agent at check in and at the gate were less than thrilled to be at work. I'm not a fan of Kayak's placement on the plane. I got put in the middle seat and none of my preferences were used.

In ATL they have two sets of departure screens. Follow what is on your airline's departure board - the ATL Airport Authority departure board had completely incorrect details about the gate assignment for my flight, which would have made me miss boarding.

Flight was delayed it was hot while sitting on the plane, one engine was working on the plane until they had to do some jimmy rigging down the runway in order for the other engine to charge up. It was ridiculous

The flight was very good and the staff was very friendly and helpful!

The only thing I would say is we tried to get on a standby earlier flight, but with our fair we couldn’t. That seems senseless to leave with open seats..

Very easy to use and convenient, you can perform any action within the same portal

In a world of delays, Delta was on time both ways! Boarding was fast and efficient. Staff was friendly. AND wifi worked.

WiFi didn’t work. Flight delayed 3 hours Crew members were illiterate Seat lean back did not work.

Flight was delayed, we could have been notified earlier and in a consistent manner. App was not refreshing for another passenger to get the latest flight status. We could have stayed and waited at the hotel instead of waiting at the airport had we known the flight was going to delayed for more than 5 hours. The toilet is too tight, and needs to be cleaned more frequently (every hour). The entertainment screen froze, the touch screen not responding to touch. We were upgraded to comfort, it is more comfortable than regular economy seats.

This wasn't my experience with Delta. It was just the Pegasus flight. Seats were very hard. Staff was kinda rough. Not very nice. Charged me for snacks. For a 4 hour flight I would've expected more.

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.

My bags were misplaced!!! Im in a foreign country with no bags

I liked that it was on time, however, the food was not good.

Offered to check carry on to final destination. This is the most absurd thing in the world. I'm carrying on because I need what is in the carry-on. I'm okay with picking up at next stop but then I will be on much larger plane that can accommodate it. Also, if there is ever a change to your flight. Go to the airport and have the people there fix your ticket. Don't do it over the phone or online with United they screwed us up and ended up with flights for our last leg that took off before our first leg.

United is one airline which regardless of how many separate United tickets in existence, if one flight breaks down, the airline will take care of all the flights.

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

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

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.

The crew acted like they had never done this and kept barking passive aggressive orders at people. + the security line + the delay + sitting on the tarmac for 2 hours + none of the apps or signage updating with correct times

More inflight connection. And leg space is horrible. And the paying for baggage I'd ridiculous!!!

My flight was originally from SAT to MCO connecting from MCO to ORD. We got diverted to ATL and than Frontier staff there was sooo un helpful first they said they couldn’t give us any accommodation since our flight first got delayed that cancelled and now it’s 221am and I am still in ATL since they said they need to create a new flight my final destination is ORD and I have been delayed twice and cancelled. With no real help the frontier app didn’t work no email updates over all such a horrible experience

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.

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

Information on your arrival and departure airports