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Cheap flights from St. Louis to Washington, D.C. from $62

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from St. Louis to Washington, D.C. departing on 3/18. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
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Cheap round-trip flights

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Frontier Logo
8:20 pm - 9:34 am
STL
-
IAD
12h 14m
1 stop
Frontier Logo
8:54 am - 11:59 pm
IAD
-
STL
16h 05m
1 stop
$275Frontier
Fri, Feb 20 - Mon, Feb 23
Multiple Airlines Logo
11:21 am - 12:36 am
STL
-
IAD
12h 15m
1 stop
Multiple Airlines Logo
2:58 pm - 11:55 pm
IAD
-
STL
9h 57m
2 stops
$279Multiple Airlines
Thu, Apr 9 - Fri, Apr 10
Frontier Logo
4:51 pm - 7:24 am
STL
-
IAD
13h 33m
1 stop
Frontier Logo
6:20 am - 1:34 pm
IAD
-
STL
8h 14m
1 stop
$281Frontier
Sun, Mar 8 - Fri, Mar 13
Frontier Logo
4:21 pm - 7:24 am
STL
-
IAD
14h 03m
1 stop
Frontier Logo
8:15 am - 1:34 pm
IAD
-
STL
30h 19m
2 stops
$282Frontier
Fri, Mar 6 - Sun, Mar 15
Delta Logo
6:59 pm - 12:27 am
STL
-
IAD
4h 28m
1 stop
Delta Logo
7:18 am - 11:09 am
IAD
-
STL
4h 51m
1 stop
$283Delta
Mon, Mar 30 - Wed, Apr 1
Multiple Airlines Logo
3:49 pm - 7:20 am
STL
-
IAD
14h 31m
1 stop
Multiple Airlines Logo
7:05 pm - 6:51 am
IAD
-
STL
36h 46m
2 stops
$284Multiple Airlines
Thu, Feb 26 - Mon, Mar 2
Delta Logo
6:00 am - 11:52 am
STL
-
IAD
4h 52m
1 stop
Delta Logo
7:29 pm - 11:58 pm
IAD
-
STL
5h 29m
1 stop
$285Delta
Thu, Apr 2 - Tue, Apr 7
Frontier Logo
3:49 pm - 7:20 am
STL
-
IAD
14h 31m
1 stop
Frontier Logo
11:15 am - 6:51 am
IAD
-
STL
20h 36m
1 stop
$286Frontier
Thu, Feb 26 - Sun, Mar 1
Frontier Logo
4:54 pm - 11:33 am
STL
-
IAD
17h 39m
1 stop
Frontier Logo
8:30 pm - 10:30 am
IAD
-
STL
15h 00m
2 stops
$288Frontier
Wed, Apr 8 - Sat, Apr 11
Frontier Logo
12:16 pm - 12:31 am
STL
-
IAD
11h 15m
1 stop
Frontier Logo
8:15 am - 7:02 am
IAD
-
STL
23h 47m
1 stop
$289Frontier
Fri, Mar 13 - Sun, Mar 15

Frontier flights from St. Louis to Washington, D.C. Dulles Intl Airport

Our best Frontier deals on St. Louis to Washington, D.C. Dulles Intl Airport flight tickets
Frontier
Feb 20
STL8:20 pmLambert-St Louis
12h 14m
1 stop
IAD9:34 amWashington, D.C. Dulles Intl
Feb 23
IAD8:54 amWashington, D.C. Dulles Intl
16h 05m
1 stop
STL11:59 pmLambert-St Louis
$275
Frontier
Feb 13
STL8:20 pmLambert-St Louis
13h 22m
1 stop
IAD10:42 amWashington, D.C. Dulles Intl
Feb 15
IAD5:39 pmWashington, D.C. Dulles Intl
14h 12m
1 stop
STL6:51 amLambert-St Louis
$277
Frontier
Mar 8
STL4:51 pmLambert-St Louis
13h 33m
1 stop
IAD7:24 amWashington, D.C. Dulles Intl
Mar 13
IAD6:20 amWashington, D.C. Dulles Intl
8h 14m
1 stop
STL1:34 pmLambert-St Louis
$281

Delta flights from St. Louis to Washington, D.C. Dulles Intl Airport

Our best Delta deals on St. Louis to Washington, D.C. Dulles Intl Airport flight tickets
Delta
May 4
STL6:50 pmLambert-St Louis
4h 52m
1 stop
IAD12:42 amWashington, D.C. Dulles Intl
May 13
IAD6:00 amWashington, D.C. Dulles Intl
4h 26m
1 stop
STL9:26 amLambert-St Louis
$283
Delta
Apr 2
STL6:00 amLambert-St Louis
4h 52m
1 stop
IAD11:52 amWashington, D.C. Dulles Intl
Apr 7
IAD7:29 pmWashington, D.C. Dulles Intl
5h 29m
1 stop
STL11:58 pmLambert-St Louis
$285
Delta
Apr 8
STL7:03 amLambert-St Louis
6h 36m
1 stop
IAD2:39 pmWashington, D.C. Dulles Intl
Apr 11
IAD6:00 amWashington, D.C. Dulles Intl
4h 46m
1 stop
STL9:46 amLambert-St Louis
$294

momondo Fare Finder

 
Customize your flight search to find flights from St. Louis to Washington, D.C. Dulles Intl Airport that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, momondo users made 832,500 searches. Data last updated February 8, 2026.
Use the filters below to find and compare flights from St. Louis to Washington, D.C. Dulles Intl Airport that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 2/20

8:20 pm-9:34 am

1 stop12h 14m

Washington, D.C. Dulles Intl

Mon 2/23

8:54 am-11:59 pm

1 stop16h 05m

$275

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 4/9

11:21 am-12:36 am

1 stop12h 15m

Washington, D.C. Dulles Intl

Fri 4/10

2:58 pm-11:55 pm

2 stops9h 57m

$279

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sun 3/8

4:51 pm-7:24 am

1 stop13h 33m

Washington, D.C. Dulles Intl

Fri 3/13

6:20 am-1:34 pm

1 stop8h 14m

$281

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 3/6

4:21 pm-7:24 am

1 stop14h 03m

Washington, D.C. Dulles Intl

Sun 3/15

8:15 am-1:34 pm

2 stops30h 19m

$282

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Mon 3/30

6:59 pm-12:27 am

1 stop4h 28m

Washington, D.C. Dulles Intl

Wed 4/1

7:18 am-11:09 am

1 stop4h 51m

$283

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 2/26

3:49 pm-7:20 am

1 stop14h 31m

Washington, D.C. Dulles Intl

Mon 3/2

7:05 pm-6:51 am

2 stops36h 46m

$284

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 4/2

6:00 am-11:52 am

1 stop4h 52m

Washington, D.C. Dulles Intl

Tue 4/7

7:29 pm-11:58 pm

1 stop5h 29m

$285

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 2/26

3:49 pm-7:20 am

1 stop14h 31m

Washington, D.C. Dulles Intl

Sun 3/1

11:15 am-6:51 am

1 stop20h 36m

$286

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Wed 4/8

4:54 pm-11:33 am

1 stop17h 39m

Washington, D.C. Dulles Intl

Sat 4/11

8:30 pm-10:30 am

2 stops15h 00m

$288

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 3/13

12:16 pm-12:31 am

1 stop11h 15m

Washington, D.C. Dulles Intl

Sun 3/15

8:15 am-7:02 am

1 stop23h 47m

$289

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first
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See travel insights to Washington, D.C. from

How to get the cheapest flight ticket from St. Louis to Washington, D.C. Dulles Intl Airport

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

What is the cheapest month to fly to Washington, D.C. Dulles Intl Airport?

In general, March is the cheapest month to fly from St. Louis to Washington, D.C. Dulles Intl Airport. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $296. If you aren’t able to travel to Washington, D.C. Dulles Intl Airport during the month of March, then flying in September is also cheap. Prices for this month can be found on momondo for an average of $315.

What is the cheapest day to depart on your flight to Washington, D.C. Dulles Intl Airport?

Our data shows that Friday is the least expensive day to fly to Washington, D.C. Dulles Intl Airport. Tickets to fly out on this day can be as low as $796. When flying out on a Sunday, the most expensive travel day of the week, you can expect to see flight prices from St. Louis to Washington, D.C. Dulles Intl Airport for around $1,193.

What is the cheapest time of day to depart on your flight to Washington, D.C. Dulles Intl Airport?

Flying to Washington, D.C. Dulles Intl Airport from St. Louis in the morning is the least expensive time of day to depart. momondo users have found prices as low as $902 when looking at flights departing in the morning. If you have a flexible travel schedule, then try to avoid flying at noon when prices are $1,158 on average. Flights to Washington, D.C. Dulles Intl Airport from St. Louis at noon are generally more expensive because this time of day is more convenient for travelers’ schedules.

What is the cheapest Lambert-St Louis to Washington, D.C. Dulles Intl flight route?

Fly from Lambert-St Louis to Washington, D.C. Dulles Intl for the best Lambert-St Louis - Washington, D.C. Dulles Intl flight prices

How far in advance should I book a flight to Washington, D.C. Dulles Intl Airport?

You are more likely to see cheaper flights to Washington, D.C. Dulles Intl Airport from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to Washington, D.C. Dulles Intl Airport for around $381 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Washington, D.C. Dulles Intl Airport from St. Louis for as low as $212 on momondo.

What cabin class options are available on Lambert-St Louis to Washington, D.C. Dulles Intl flights?

There are 4 cabin classes available to choose from on Lambert-St Louis to Washington, D.C. Dulles Intl flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on St. Louis to Washington, D.C. Dulles Intl Airport flights?

You could potentially save up to 68% on your flight if you consider stops on a St. Louis to Washington, D.C. Dulles Intl Airport flight.

How have St. Louis to Washington, D.C. Dulles Intl Airport flight prices changed over time?

As of February 2026, prices for St. Louis to Washington, D.C. Dulles Intl Airport flights are approximately 20% more expensive when compared to flights at the same time last year.

When to book flights from St. Louis to Washington, D.C. Dulles Intl Airport

Are you open to changing your travel dates? Check out the ideal times to fly from St. Louis to Washington, D.C. Dulles Intl Airport according to our flight data. Find out which month and days have the cheapest flights.
Estimated round-trip price

Cheap St. Louis to Washington, D.C. Dulles Intl Airport (STL to IAD) flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from St. Louis to Washington, D.C. Dulles Intl Airport

Best Price Found

$296

Fastest flight time

2h 06m

Direct flights

Every day
The best one-way flight to Washington, D.C. Dulles Intl Airport from St. Louis in the past 72 hours is $296. The best round-trip flight deal from St. Louis to Washington, D.C. Dulles Intl Airport found on momondo in the last 72 hours is $471.
The fastest flight from St. Louis to Washington, D.C. Dulles Intl Airport takes 2h 06m
Direct flights go from St. Louis to Washington, D.C. Dulles Intl Airport every day.
Search flight deals

  • How far is Lambert-St Louis to Washington, D.C. Dulles Intl by plane?

    The straight-line distance from Lambert-St Louis to Washington, D.C. Dulles Intl is 685.9 mi. Flights usually cover this in 2h 06m, depending on flying conditions and air traffic around both airports.

  • When did momondo last update prices for flights from Lambert-St Louis Airport to Washington, D.C. Dulles Intl Airport?

    Prices for flights from Lambert-St Louis Airport to Washington, D.C. Dulles Intl Airport are refreshed on a daily basis.

  • How many operators does momondo search for flights from Lambert-St Louis Airport to Washington, D.C. Dulles Intl Airport?

  • How old do you have to be to fly from Lambert-St Louis Airport to Washington, D.C. Dulles Intl Airport?

    Although the minimum age for a child to fly alone is five, airlines that offer an unaccompanied minor (UMNR) service may have their own age limits, which could be impacted by factors such as flight length, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Lambert-St Louis Airport to Washington, D.C. Dulles Intl Airport.

  • What documentation or ID do you need to fly to Washington, D.C. Dulles Intl Airport?

    The necessary travel and health documents for your Washington, D.C. Dulles Intl Airport trip may vary depending on your travel plans and individual circumstances. Generally, you should have various documents, such as a national ID card or driver's license and a passport that is valid for six months beyond your scheduled arrival date. We recommend seeking advice from your airline or a trusted third party, such as IATA.

  • What is the most popular plane model from St. Louis to Washington, D.C. Dulles Intl Airport?

  • What is the most popular airline from St. Louis to Washington, D.C. Dulles Intl Airport?

Best airlines flying from St. Louis to Washington, D.C. Dulles Intl Airport

Compare and see reviews for airlines that fly from St. Louis to Washington, D.C. Dulles Intl Airport with momondo
Airline
Rating
Free Cancellation
Price
FrontierPriceFrom $73Free CancellationRating
5.7
3,052 reviews
Search Frontier flights
DeltaPriceFrom $99Free CancellationRating
7.9
8,172 reviews
Search Delta flights
American AirlinesPriceFrom $257Free CancellationRating
7.2
11,249 reviews
Search American Airlines flights
United AirlinesPriceFrom $263Free CancellationRating
7.4
9,254 reviews
Search United Airlines flights

  • United Airlines Flights From St. Louis to Washington, D.C. Dulles Intl Airport

    United Airlines flight deals from St. Louis to Washington, D.C. Dulles Intl Airport start from $263 round-trip. Over the 13 United Airlines flights for this route in a normal week, average airfare is usually $454 round-trip - but some users have found much cheaper deals with momondo.

Traveling to a place near Washington, D.C.?

Book flights to Washington, D.C. if you plan to visit one of these locations
Alexandria
National Harbor
Gettysburg
Arlington
Winchester
Waldorf
Woodbridge
Tysons
Laurel
Colonial Beach
Silver Spring
Towson
Fredericksburg
Gaithersburg
Rockville
Manassas
Springfield
Sterling
Fairfax
Linthicum Heights

Why use momondo?

Why should I use momondo to find a flight deal from St. Louis to Washington, D.C.?

We help find the flight that best suits your needs, momondo compares prices from hundreds of airlines and travel agents and helps you filter them to find the best flight from St. Louis to Washington, D.C. for you.

Can I find flights from St. Louis to Washington, D.C. with flexible booking policies on momondo?

Yes. momondo allows you to filter the results for St. Louis to Washington, D.C. flights to just show those with flexible booking policies.

How can momondo help me find flights from St. Louis to Washington, D.C.?

momondo offers useful filters to help you find the right flight. Choose specific flight times, airports or even what payment method you prefer. We have numerous options to help you book your ideal flight from St. Louis to Washington, D.C..

I’m not ready to book a flight from St. Louis to Washington, D.C. right now. Can momondo alert me if prices change?

Yes. momondo can track prices for St. Louis to Washington, D.C. flights and alert you when they change. Perform a search to set up the price alert. All that is required is a valid email address.

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