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Cheap flights from St. Louis to Washington, D.C. from $55

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 11/13. 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
10:57 am - 4:58 pmSTL-IAD
5h 01m1 stop
Frontier Logo
7:01 pm - 9:40 amIAD-STL
15h 39m1 stop
$200Frontier
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Sun, Dec 21 - Wed, Dec 24
Frontier Logo
4:27 pm - 9:03 pmSTL-IAD
27h 36m1 stop
Frontier Logo
7:01 pm - 9:40 amIAD-STL
15h 39m1 stop
$201Frontier
Find Deal
Sat, Dec 20 - Wed, Dec 24
Frontier Logo
10:25 am - 7:51 pmSTL-IAD
8h 26m1 stop
Frontier Logo
6:00 am - 10:12 amIAD-STL
5h 12m1 stop
$202Frontier
Find Deal
Mon, Nov 3 - Thu, Nov 6
Frontier Logo
4:27 pm - 11:38 amSTL-IAD
18h 11m2 stops
Frontier Logo
7:11 pm - 9:40 amIAD-STL
15h 29m1 stop
$203Frontier
Find Deal
Sun, Dec 21 - Sat, Dec 27
Frontier Logo
11:07 am - 4:34 pmSTL-IAD
4h 27m1 stop
Frontier Logo
8:36 pm - 4:18 pmIAD-STL
20h 42m1 stop
$204Frontier
Find Deal
Thu, Nov 6 - Sat, Nov 8
Frontier Logo
4:56 pm - 12:11 amSTL-IAD
6h 15m1 stop
Frontier Logo
8:40 am - 9:07 amIAD-STL
25h 27m2 stops
$207Frontier
Find Deal
Fri, Nov 14 - Tue, Nov 18
Frontier Logo
10:42 am - 4:43 pmSTL-IAD
5h 01m1 stop
Frontier Logo
10:23 pm - 10:33 pmIAD-STL
25h 10m1 stop
$211Frontier
Find Deal
Thu, Jan 15 - Mon, Jan 19
Multiple Airlines Logo
10:48 am - 4:37 pmSTL-IAD
4h 49m1 stop
Multiple Airlines Logo
7:06 pm - 10:56 amIAD-STL
16h 50m2 stops
$223Multiple Airlines
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Tue, Dec 23 - Mon, Dec 29
United Airlines Logo
8:30 am - 11:40 amSTL-IAD
2h 10mnonstop
United Airlines Logo
5:19 pm - 11:44 pmIAD-STL
7h 25m1 stop
$273United Airlines
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Wed, Dec 3 - Sat, Dec 6
United Airlines Logo
8:30 am - 11:40 amSTL-IAD
2h 10mnonstop
United Airlines Logo
8:40 am - 10:07 amIAD-STL
2h 27mnonstop
$274United Airlines
Find Deal
Wed, Dec 3 - Sat, Dec 6

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
Dec 21
STL10:57 amLambert-St Louis
5h 01m
1 stop
IAD4:58 pmWashington, D.C. Dulles Intl
Dec 24
IAD7:01 pmWashington, D.C. Dulles Intl
15h 39m
1 stop
STL9:40 amLambert-St Louis
$200
Find similar
Frontier
Dec 20
STL4:27 pmLambert-St Louis
27h 36m
1 stop
IAD9:03 pmWashington, D.C. Dulles Intl
Dec 24
IAD7:01 pmWashington, D.C. Dulles Intl
15h 39m
1 stop
STL9:40 amLambert-St Louis
$201
Find similar
Frontier
Nov 3
STL10:25 amLambert-St Louis
8h 26m
1 stop
IAD7:51 pmWashington, D.C. Dulles Intl
Nov 6
IAD6:00 amWashington, D.C. Dulles Intl
5h 12m
1 stop
STL10:12 amLambert-St Louis
$202
Find similar

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

Our best United Airlines deals on St. Louis to Washington, D.C. Dulles Intl Airport flight tickets
United Airlines
Dec 3
STL8:30 amLambert-St Louis
2h 10m
IAD11:40 amWashington, D.C. Dulles Intl
Dec 6
IAD5:19 pmWashington, D.C. Dulles Intl
7h 25m
1 stop
STL11:44 pmLambert-St Louis
$273
Find similar
United Airlines
Dec 3
STL8:30 amLambert-St Louis
2h 10m
IAD11:40 amWashington, D.C. Dulles Intl
Dec 6
IAD8:40 amWashington, D.C. Dulles Intl
2h 27m
STL10:07 amLambert-St Louis
$274
Find similar
United Airlines
Nov 13
STL8:25 amLambert-St Louis
2h 08m
IAD11:33 amWashington, D.C. Dulles Intl
Nov 16
IAD8:30 amWashington, D.C. Dulles Intl
6h 54m
1 stop
STL2:24 pmLambert-St Louis
$547
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 October 30, 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

Sun 12/21

10:57 am-4:58 pm

1 stop5h 01m

Washington, D.C. Dulles Intl

Wed 12/24

7:01 pm-9:40 am

1 stop15h 39m

$200

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sat 12/20

4:27 pm-9:03 pm

1 stop27h 36m

Washington, D.C. Dulles Intl

Wed 12/24

7:01 pm-9:40 am

1 stop15h 39m

$201

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Mon 11/3

10:25 am-7:51 pm

1 stop8h 26m

Washington, D.C. Dulles Intl

Thu 11/6

6:00 am-10:12 am

1 stop5h 12m

$202

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sun 12/21

4:27 pm-11:38 am

2 stops18h 11m

Washington, D.C. Dulles Intl

Sat 12/27

7:11 pm-9:40 am

1 stop15h 29m

$203

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 11/6

11:07 am-4:34 pm

1 stop4h 27m

Washington, D.C. Dulles Intl

Sat 11/8

8:36 pm-4:18 pm

1 stop20h 42m

$204

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 11/14

4:56 pm-12:11 am

1 stop6h 15m

Washington, D.C. Dulles Intl

Tue 11/18

8:40 am-9:07 am

2 stops25h 27m

$207

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 1/15

10:42 am-4:43 pm

1 stop5h 01m

Washington, D.C. Dulles Intl

Mon 1/19

10:23 pm-10:33 pm

1 stop25h 10m

$211

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 12/23

10:48 am-4:37 pm

1 stop4h 49m

Washington, D.C. Dulles Intl

Mon 12/29

7:06 pm-10:56 am

2 stops16h 50m

$223

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Wed 12/3

8:30 am-11:40 am

Nonstop2h 10m

Washington, D.C. Dulles Intl

Sat 12/6

5:19 pm-11:44 pm

1 stop7h 25m

$273

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Wed 12/3

8:30 am-11:40 am

Nonstop2h 10m

Washington, D.C. Dulles Intl

Sat 12/6

8:40 am-10:07 am

Nonstop2h 27m

$274

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 $300. 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 $304.

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 $786. 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 $1,128.

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 $1,151 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 $373 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 $246 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 18% 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 October 2025, prices for St. Louis to Washington, D.C. Dulles Intl Airport flights are approximately 34% cheaper 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

$298

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 $298. 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 $465.
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 10m, 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 $111Free CancellationRating
5.8
3,122 reviews
Search Frontier flights
DeltaPriceFrom $124Free CancellationRating
7.9
7,998 reviews
Search Delta flights
United AirlinesPriceFrom $238Free CancellationRating
7.4
8,998 reviews
Search United Airlines flights
American AirlinesPriceFrom $250Free CancellationRating
7.2
11,035 reviews
Search American 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 $238 round-trip. Over the 8 United Airlines flights for this route in a normal week, average airfare is usually $426 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
Harpers Ferry
Towson
Rockville
Manassas
Reston
Gaithersburg
Fairfax
Sterling

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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