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Cheap flights from St. Louis to Washington, D.C. from $66

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 11/18. 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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Find the cheapest flights from St. Louis to Washington, D.C.

Cheap round-trip flights

Frontier Logo
11:32 am - 11:29 pmSTL-IAD
10h 57m1 stop
Frontier Logo
6:15 am - 10:37 amIAD-STL
5h 22m1 stop
$184Frontier
Find Deal
Thu, Oct 16 - Thu, Oct 23
Frontier Logo
4:00 pm - 11:39 pmSTL-IAD
6h 39m1 stop
Frontier Logo
10:09 pm - 3:04 pmIAD-STL
17h 55m2 stops
$186Frontier
Find Deal
Thu, Oct 2 - Sun, Oct 5
Delta Logo
6:14 pm - 11:00 pmSTL-IAD
3h 46m1 stop
Delta Logo
6:05 am - 9:37 amIAD-STL
4h 32m1 stop
$197Delta
Find Deal
Tue, Oct 14 - Wed, Oct 15
United Airlines Logo
8:05 am - 11:15 amSTL-IAD
2h 10mnonstop
United Airlines Logo
8:40 am - 10:02 amIAD-STL
2h 22mnonstop
$215United Airlines
Find Deal
Fri, Oct 10 - Sun, Oct 12
United Airlines Logo
5:28 pm - 12:21 amSTL-IAD
5h 53m1 stop
United Airlines Logo
8:40 am - 10:02 amIAD-STL
2h 22mnonstop
$256United Airlines
Find Deal
Fri, Oct 10 - Sun, Oct 12
American Airlines Logo
12:51 pm - 6:54 pmSTL-IAD
5h 03m1 stop
American Airlines Logo
8:09 am - 12:06 pmIAD-STL
4h 57m1 stop
$276American Airlines
Find Deal
Tue, Oct 14 - Wed, Oct 15
Delta Logo
5:12 pm - 12:18 amSTL-IAD
6h 06m1 stop
Delta Logo
7:01 am - 10:49 amIAD-STL
4h 48m1 stop
$277Delta
Find Deal
Fri, Nov 14 - Sun, Nov 23
Multiple Airlines Logo
11:07 am - 11:29 pmSTL-IAD
11h 22m1 stop
Multiple Airlines Logo
7:10 am - 6:10 pmIAD-STL
12h 00m2 stops
$294Multiple Airlines
Find Deal
Thu, Oct 30 - Sat, Nov 1
American Airlines Logo
6:52 am - 1:34 pmSTL-IAD
5h 42m1 stop
American Airlines Logo
9:12 am - 1:14 pmIAD-STL
5h 02m1 stop
$301American Airlines
Find Deal
Tue, Dec 16 - Tue, Dec 23
Multiple Airlines Logo
11:32 am - 11:29 pmSTL-IAD
10h 57m1 stop
Multiple Airlines Logo
7:15 am - 6:10 pmIAD-STL
11h 55m2 stops
$307Multiple Airlines
Find Deal
Thu, Oct 16 - Sat, Oct 18

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
Oct 10
STL8:05 amLambert-St Louis
2h 10m
IAD11:15 amWashington, D.C. Dulles Intl
Oct 12
IAD8:40 amWashington, D.C. Dulles Intl
2h 22m
STL10:02 amLambert-St Louis
$215
Find similar
United Airlines
Oct 10
STL5:28 pmLambert-St Louis
5h 53m
1 stop
IAD12:21 amWashington, D.C. Dulles Intl
Oct 12
IAD8:40 amWashington, D.C. Dulles Intl
2h 22m
STL10:02 amLambert-St Louis
$256
Find similar
United Airlines
Oct 8
STL6:30 amLambert-St Louis
6h 21m
1 stop
IAD1:51 pmWashington, D.C. Dulles Intl
Oct 12
IAD8:40 amWashington, D.C. Dulles Intl
2h 22m
STL10:02 amLambert-St Louis
$274
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
Oct 16
STL11:32 amLambert-St Louis
10h 57m
1 stop
IAD11:29 pmWashington, D.C. Dulles Intl
Oct 23
IAD6:15 amWashington, D.C. Dulles Intl
5h 22m
1 stop
STL10:37 amLambert-St Louis
$184
Find similar
Frontier
Oct 2
STL4:00 pmLambert-St Louis
6h 39m
1 stop
IAD11:39 pmWashington, D.C. Dulles Intl
Oct 5
IAD10:09 pmWashington, D.C. Dulles Intl
17h 55m
2 stops
STL3:04 pmLambert-St Louis
$186
Find similar
Frontier
Oct 1
STL7:55 pmLambert-St Louis
16h 00m
2 stops
IAD12:55 pmWashington, D.C. Dulles Intl
Oct 5
IAD6:10 amWashington, D.C. Dulles Intl
9h 54m
1 stop
STL3:04 pmLambert-St Louis
$190
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 September 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 10/16

11:32 am-11:29 pm

1 stop10h 57m

Washington, D.C. Dulles Intl

Thu 10/23

6:15 am-10:37 am

1 stop5h 22m

$184

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 10/2

4:00 pm-11:39 pm

1 stop6h 39m

Washington, D.C. Dulles Intl

Sun 10/5

10:09 pm-3:04 pm

2 stops17h 55m

$186

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 10/14

6:14 pm-11:00 pm

1 stop3h 46m

Washington, D.C. Dulles Intl

Wed 10/15

6:05 am-9:37 am

1 stop4h 32m

$197

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 10/10

8:05 am-11:15 am

Nonstop2h 10m

Washington, D.C. Dulles Intl

Sun 10/12

8:40 am-10:02 am

Nonstop2h 22m

$215

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 10/10

5:28 pm-12:21 am

1 stop5h 53m

Washington, D.C. Dulles Intl

Sun 10/12

8:40 am-10:02 am

Nonstop2h 22m

$256

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 10/14

12:51 pm-6:54 pm

1 stop5h 03m

Washington, D.C. Dulles Intl

Wed 10/15

8:09 am-12:06 pm

1 stop4h 57m

$276

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 11/14

5:12 pm-12:18 am

1 stop6h 06m

Washington, D.C. Dulles Intl

Sun 11/23

7:01 am-10:49 am

1 stop4h 48m

$277

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 10/30

11:07 am-11:29 pm

1 stop11h 22m

Washington, D.C. Dulles Intl

Sat 11/1

7:10 am-6:10 pm

2 stops12h 00m

$294

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 12/16

6:52 am-1:34 pm

1 stop5h 42m

Washington, D.C. Dulles Intl

Tue 12/23

9:12 am-1:14 pm

1 stop5h 02m

$301

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 10/16

11:32 am-11:29 pm

1 stop10h 57m

Washington, D.C. Dulles Intl

Sat 10/18

7:15 am-6:10 pm

2 stops11h 55m

$307

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 typical price of a round-trip flight between St. Louis and Washington, D.C. Dulles Intl Airport?

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 $750. 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 $1,118.

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 $1,184 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 $377 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?

No. A direct flight is the cheapest option for a flight between St. Louis to Washington, D.C. Dulles Intl Airport.

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

As of September 2025, prices for St. Louis to Washington, D.C. Dulles Intl Airport flights are approximately 50% 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

$405

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 $405. 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 $590.
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 08m, 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
American AirlinesPriceFrom $129Free CancellationRating
7.2
10,000 reviews
Search American Airlines flights
DeltaPriceFrom $168Free CancellationRating
7.9
7,957 reviews
Search Delta flights
United AirlinesPriceFrom $211Free CancellationRating
7.4
8,924 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 $211 round-trip. Over the 12 United Airlines flights for this route in a normal week, average airfare is usually $444 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
Gettysburg
National Harbor
Arlington
Winchester
Woodbridge
Waldorf
Tysons
Laurel
Colonial Beach
Silver Spring
Fredericksburg
Harpers Ferry
Towson
Rockville
Manassas
Reston
Fairfax
Glen Burnie
Gaithersburg

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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