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Cheap flights from St. Louis to Washington, D.C. from $99

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 8/9. 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
2:52 pm - 11:26 pmSTL-IAD
7h 34m1 stop
Frontier Logo
6:10 am - 1:33 pmIAD-STL
8h 23m1 stop
$198Frontier
Find Deal
Sat, Aug 16 - Sat, Aug 23
Frontier Logo
3:02 pm - 11:00 pmSTL-IAD
6h 58m1 stop
Frontier Logo
6:10 am - 12:56 pmIAD-STL
7h 46m1 stop
$208Frontier
Find Deal
Sat, Aug 30 - Mon, Sep 1
Delta Logo
5:20 pm - 11:18 pmSTL-IAD
4h 58m1 stop
Delta Logo
5:10 pm - 8:23 pmIAD-STL
4h 13m1 stop
$237Delta
Find Deal
Sat, Oct 11 - Tue, Oct 14
United Airlines Logo
6:35 am - 2:37 pmSTL-IAD
7h 02m1 stop
United Airlines Logo
8:40 am - 10:02 amIAD-STL
2h 22mnonstop
$239United Airlines
Find Deal
Wed, Aug 27 - Wed, Sep 3
United Airlines Logo
7:04 pm - 12:32 amSTL-IAD
4h 28m1 stop
United Airlines Logo
8:40 am - 10:02 amIAD-STL
2h 22mnonstop
$244United Airlines
Find Deal
Tue, Sep 2 - Thu, Sep 4
Delta Logo
6:40 am - 11:28 amSTL-IAD
3h 48m1 stop
Delta Logo
12:35 pm - 4:05 pmIAD-STL
4h 30m1 stop
$254Delta
Find Deal
Thu, Sep 18 - Sat, Oct 4
American Airlines Logo
6:29 am - 1:49 pmSTL-IAD
6h 20m1 stop
American Airlines Logo
7:17 pm - 11:07 pmIAD-STL
4h 50m1 stop
$271American Airlines
Find Deal
Sat, Sep 13 - Sat, Sep 20
American Airlines Logo
6:06 am - 6:52 pmSTL-IAD
11h 46m2 stops
American Airlines Logo
7:44 am - 1:51 pmIAD-STL
7h 07m1 stop
$299American Airlines
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Tue, Aug 26 - Wed, Aug 27
Logo
10:37 am - 2:23 pmSTL-IAD
26h 46m3 stops
Logo
4:56 pm - 1:32 pmIAD-STL
21h 36m3 stops
$318
Find Deal
Sun, Aug 17 - Thu, Aug 21
Logo
10:37 am - 2:23 pmSTL-IAD
26h 46m3 stops
Logo
11:04 am - 6:41 pmIAD-STL
8h 37m2 stops
$319
Find Deal
Thu, Aug 14 - Sun, Aug 17

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
Aug 16
STL2:52 pmLambert-St Louis
7h 34m
1 stop
IAD11:26 pmWashington, D.C. Dulles Intl
Aug 23
IAD6:10 amWashington, D.C. Dulles Intl
8h 23m
1 stop
STL1:33 pmLambert-St Louis
$198
Find similar
Frontier
Aug 30
STL3:02 pmLambert-St Louis
6h 58m
1 stop
IAD11:00 pmWashington, D.C. Dulles Intl
Sep 1
IAD6:10 amWashington, D.C. Dulles Intl
7h 46m
1 stop
STL12:56 pmLambert-St Louis
$208
Find similar
Frontier
Aug 16
STL2:52 pmLambert-St Louis
7h 34m
1 stop
IAD11:26 pmWashington, D.C. Dulles Intl
Aug 24
IAD9:33 pmWashington, D.C. Dulles Intl
17h 48m
1 stop
STL2:21 pmLambert-St Louis
$215
Find similar

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
Oct 11
STL5:20 pmLambert-St Louis
4h 58m
1 stop
IAD11:18 pmWashington, D.C. Dulles Intl
Oct 14
IAD5:10 pmWashington, D.C. Dulles Intl
4h 13m
1 stop
STL8:23 pmLambert-St Louis
$237
Find similar
Delta
Sep 18
STL6:40 amLambert-St Louis
3h 48m
1 stop
IAD11:28 amWashington, D.C. Dulles Intl
Oct 4
IAD12:35 pmWashington, D.C. Dulles Intl
4h 30m
1 stop
STL4:05 pmLambert-St Louis
$254
Find similar
Delta
Aug 30
STL5:11 pmLambert-St Louis
5h 10m
1 stop
IAD11:21 pmWashington, D.C. Dulles Intl
Aug 31
IAD6:15 pmWashington, D.C. Dulles Intl
4h 40m
1 stop
STL9:55 pmLambert-St Louis
$255
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 July 31, 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

Sat 8/16

2:52 pm-11:26 pm

1 stop7h 34m

Washington, D.C. Dulles Intl

Sat 8/23

6:10 am-1:33 pm

1 stop8h 23m

$198

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sat 8/30

3:02 pm-11:00 pm

1 stop6h 58m

Washington, D.C. Dulles Intl

Mon 9/1

6:10 am-12:56 pm

1 stop7h 46m

$208

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sat 10/11

5:20 pm-11:18 pm

1 stop4h 58m

Washington, D.C. Dulles Intl

Tue 10/14

5:10 pm-8:23 pm

1 stop4h 13m

$237

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Wed 8/27

6:35 am-2:37 pm

1 stop7h 02m

Washington, D.C. Dulles Intl

Wed 9/3

8:40 am-10:02 am

Nonstop2h 22m

$239

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 9/2

7:04 pm-12:32 am

1 stop4h 28m

Washington, D.C. Dulles Intl

Thu 9/4

8:40 am-10:02 am

Nonstop2h 22m

$244

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 9/18

6:40 am-11:28 am

1 stop3h 48m

Washington, D.C. Dulles Intl

Sat 10/4

12:35 pm-4:05 pm

1 stop4h 30m

$254

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sat 9/13

6:29 am-1:49 pm

1 stop6h 20m

Washington, D.C. Dulles Intl

Sat 9/20

7:17 pm-11:07 pm

1 stop4h 50m

$271

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 8/26

6:06 am-6:52 pm

2 stops11h 46m

Washington, D.C. Dulles Intl

Wed 8/27

7:44 am-1:51 pm

1 stop7h 07m

$299

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sun 8/17

10:37 am-2:23 pm

3 stops26h 46m

Washington, D.C. Dulles Intl

Thu 8/21

4:56 pm-1:32 pm

3 stops21h 36m

$318

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 8/14

10:37 am-2:23 pm

3 stops26h 46m

Washington, D.C. Dulles Intl

Sun 8/17

11:04 am-6:41 pm

2 stops8h 37m

$319

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, August 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 $294. If you aren’t able to travel to Washington, D.C. Dulles Intl Airport during the month of August, then flying in January is also cheap. Prices for this month can be found on momondo for an average of $299.

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 $747. When flying out on a Monday, 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 $1,150.

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 $1,232 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 $378 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 $249 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 July 2025, prices for St. Louis to Washington, D.C. Dulles Intl Airport flights are approximately 18% 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

$99

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 $99. 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 $198.
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
8.0
7,981 reviews
Search Delta flights
United AirlinesPriceFrom $209Free CancellationRating
7.4
8,900 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 $209 round-trip. Over the 14 United Airlines flights for this route in a normal week, average airfare is usually $437 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
Arlington
National Harbor
Winchester
Woodbridge
Laurel
Tysons
Silver Spring
Waldorf
Fredericksburg
Manassas
Harpers Ferry
Towson
Rockville
Colonial Beach
Gaithersburg
Fairfax
Reston
Glen Burnie

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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