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Cheap flights from St. Louis to Washington, D.C. from $70

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 1/24. 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
5:42 pm - 8:40 am
STL
-
IAD
13h 58m1 stop
Frontier Logo
5:33 pm - 6:51 am
IAD
-
STL
14h 18m1 stop
$205Frontier
Thu, Jan 22 - Fri, Jan 23
Frontier Logo
3:43 pm - 2:08 pm
STL
-
IAD
21h 25m2 stops
Frontier Logo
8:35 am - 10:33 pm
IAD
-
STL
14h 58m1 stop
$211Frontier
Thu, Jan 8 - Mon, Jan 12
Frontier Logo
10:48 am - 4:37 pm
STL
-
IAD
4h 49m1 stop
Frontier Logo
5:35 am - 9:40 am
IAD
-
STL
5h 05m1 stop
$214Frontier
Tue, Dec 30 - Sun, Jan 4
Frontier Logo
10:40 am - 9:03 pm
STL
-
IAD
9h 23m1 stop
Frontier Logo
6:00 am - 2:48 pm
IAD
-
STL
9h 48m1 stop
$218Frontier
Mon, Jan 5 - Fri, Jan 9
Frontier Logo
10:42 am - 6:16 pm
STL
-
IAD
6h 34m1 stop
Frontier Logo
9:58 pm - 10:33 pm
IAD
-
STL
25h 35m1 stop
$219Frontier
Thu, Jan 1 - Mon, Jan 5
Frontier Logo
4:51 pm - 7:24 am
STL
-
IAD
13h 33m1 stop
Frontier Logo
8:09 am - 7:07 am
IAD
-
STL
23h 58m1 stop
$232Frontier
Fri, Mar 6 - Sun, Mar 8
Multiple Airlines Logo
8:39 am - 9:13 pm
STL
-
IAD
11h 34m2 stops
Multiple Airlines Logo
5:50 pm - 6:51 am
IAD
-
STL
14h 01m1 stop
$242Multiple Airlines
Fri, Jan 16 - Sun, Jan 18
Frontier Logo
5:11 pm - 9:08 am
STL
-
IAD
14h 57m1 stop
Frontier Logo
6:00 am - 2:48 pm
IAD
-
STL
9h 48m1 stop
$246Frontier
Fri, Jan 9 - Sun, Jan 11
Delta Logo
12:00 pm - 5:17 pm
STL
-
IAD
4h 17m1 stop
Delta Logo
5:26 pm - 8:43 pm
IAD
-
STL
4h 17m1 stop
$251Delta
Tue, Jan 13 - Tue, Jan 20
American Airlines Logo
10:17 am - 5:16 pm
STL
-
IAD
5h 59m1 stop
American Airlines Logo
11:34 am - 3:04 pm
IAD
-
STL
4h 30m1 stop
$255American Airlines
Tue, Jan 13 - Tue, Jan 20

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

Our best American Airlines deals on St. Louis to Washington, D.C. Dulles Intl Airport flight tickets
American Airlines
Jan 13
STL10:17 amLambert-St Louis
5h 59m
1 stop
IAD5:16 pmWashington, D.C. Dulles Intl
Jan 20
IAD11:34 amWashington, D.C. Dulles Intl
4h 30m
1 stop
STL3:04 pmLambert-St Louis
$255
Find similar
American Airlines
Jan 12
STL3:54 pmLambert-St Louis
6h 18m
1 stop
IAD11:12 pmWashington, D.C. Dulles Intl
Jan 19
IAD5:46 pmWashington, D.C. Dulles Intl
6h 26m
1 stop
STL11:12 pmLambert-St Louis
$323
Find similar
American Airlines
Jan 7
STL6:52 amLambert-St Louis
4h 44m
1 stop
IAD12:36 pmWashington, D.C. Dulles Intl
Jan 10
IAD11:34 amWashington, D.C. Dulles Intl
4h 30m
1 stop
STL3:04 pmLambert-St Louis
$325
Find similar

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
Jan 22
STL5:42 pmLambert-St Louis
13h 58m
1 stop
IAD8:40 amWashington, D.C. Dulles Intl
Jan 23
IAD5:33 pmWashington, D.C. Dulles Intl
14h 18m
1 stop
STL6:51 amLambert-St Louis
$205
Find similar
Frontier
Dec 18
STL10:42 amLambert-St Louis
6h 34m
1 stop
IAD6:16 pmWashington, D.C. Dulles Intl
Jan 8
IAD6:00 amWashington, D.C. Dulles Intl
9h 48m
1 stop
STL2:48 pmLambert-St Louis
$213
Find similar
Frontier
Dec 30
STL10:48 amLambert-St Louis
4h 49m
1 stop
IAD4:37 pmWashington, D.C. Dulles Intl
Jan 4
IAD5:35 amWashington, D.C. Dulles Intl
5h 05m
1 stop
STL9:40 amLambert-St Louis
$214
Find similar

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 December 16, 2025.
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

Thu 1/22

5:42 pm-8:40 am

1 stop13h 58m

Washington, D.C. Dulles Intl

Fri 1/23

5:33 pm-6:51 am

1 stop14h 18m

$205

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 1/8

3:43 pm-2:08 pm

2 stops21h 25m

Washington, D.C. Dulles Intl

Mon 1/12

8:35 am-10:33 pm

1 stop14h 58m

$211

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 12/30

10:48 am-4:37 pm

1 stop4h 49m

Washington, D.C. Dulles Intl

Sun 1/4

5:35 am-9:40 am

1 stop5h 05m

$214

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Mon 1/5

10:40 am-9:03 pm

1 stop9h 23m

Washington, D.C. Dulles Intl

Fri 1/9

6:00 am-2:48 pm

1 stop9h 48m

$218

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 1/1

10:42 am-6:16 pm

1 stop6h 34m

Washington, D.C. Dulles Intl

Mon 1/5

9:58 pm-10:33 pm

1 stop25h 35m

$219

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 3/6

4:51 pm-7:24 am

1 stop13h 33m

Washington, D.C. Dulles Intl

Sun 3/8

8:09 am-7:07 am

1 stop23h 58m

$232

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 1/16

8:39 am-9:13 pm

2 stops11h 34m

Washington, D.C. Dulles Intl

Sun 1/18

5:50 pm-6:51 am

1 stop14h 01m

$242

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 1/9

5:11 pm-9:08 am

1 stop14h 57m

Washington, D.C. Dulles Intl

Sun 1/11

6:00 am-2:48 pm

1 stop9h 48m

$246

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 1/13

12:00 pm-5:17 pm

1 stop4h 17m

Washington, D.C. Dulles Intl

Tue 1/20

5:26 pm-8:43 pm

1 stop4h 17m

$251

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 1/13

10:17 am-5:16 pm

1 stop5h 59m

Washington, D.C. Dulles Intl

Tue 1/20

11:34 am-3:04 pm

1 stop4h 30m

$255

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 $290. If you aren’t able to travel to Washington, D.C. Dulles Intl Airport during the month of March, then flying in January is also cheap. Prices for this month can be found on momondo for an average of $310.

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 $809. When flying out on a Saturday, 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 $1,157.

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 evening is the least expensive time of day to depart. momondo users have found prices as low as $262 when looking at flights departing in the evening. If you have a flexible travel schedule, then try to avoid flying at noon when prices are $1,141 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 $372 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 26% 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 December 2025, prices for St. Louis to Washington, D.C. Dulles Intl Airport flights are approximately 34% 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

$238

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 $238. 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 $576.
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 $113Free CancellationRating
5.8
3,082 reviews
Search Frontier flights
DeltaPriceFrom $124Free CancellationRating
7.9
8,010 reviews
Search Delta flights
American AirlinesPriceFrom $250Free CancellationRating
7.2
11,048 reviews
Search American Airlines flights
United AirlinesPriceFrom $264Free CancellationRating
7.4
9,094 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 $264 round-trip. Over the 6 United Airlines flights for this route in a normal week, average airfare is usually $459 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
Woodbridge
Waldorf
Tysons
Laurel
Colonial Beach
Silver Spring
Fredericksburg
Towson
Harpers Ferry
Rockville
Gaithersburg
Reston
Manassas
Sterling
Fairfax

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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