How long is the flight from St. Louis to Washington, D.C. Dulles Intl Airport?

A quick flight from St. Louis to Washington, D.C. Dulles Intl Airport can take about 7h 07m. Delta provides one of the quickest options available for as low as $197. There are 694 mi between St. Louis and Washington, D.C. Dulles Intl Airport.

What are the cheapest airlines flying from St. Louis to Washington, D.C. Dulles Intl Airport round-trip?

Currently priced at $129, American Airlines will fly you from St. Louis to Washington, D.C. Dulles Intl Airport and back. In addition to American Airlines, many other airlines offer competitively priced options for your trip. Search Cheapflights for deals from Delta and United Airlines - these airlines can fly you to your destination from $168 and $211, respectively. American Airlines is 65% cheaper than the average price of flights available within the next 90 days to this destination.

What is the cheapest day to fly from St. Louis to Washington, D.C. Dulles Intl Airport?

Travelers seeking maximum savings on their St. Louis to Washington, D.C. Dulles Intl Airport flight should consider departing on Saturday afternoons when fares are most often at their lowest. Monday at noon flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from St. Louis to Washington, D.C. Dulles Intl Airport

The most flights from STL to IAD are scheduled on a Monday (7 on average). You will have fewer flight options on Wednesday, which is when the least amount of flights are scheduled (6 on average).

In terms of precipitation, rainfall in Washington, D.C. Dulles Intl Airport ranges from 2.6 - 4.0 inches per month. May is typically the wettest month, when rainfall can reach 4.0 in. February is typically the driest time to visit Washington, D.C. Dulles Intl Airport when rainfall is around 2.6 in.

If weather is an important factor for your trip to Washington, D.C. Dulles Intl Airport, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 80.6 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 35.6 F).

What are the cheapest flights from St. Louis to Washington, D.C. Dulles Intl Airport?

On average you can expect to pay $1,362 for a flight from St. Louis to Washington, D.C. Dulles Intl Airport. The cheapest flight overall is $138 while the most popular route, (Lambert-St Louis - Washington, D.C. Dulles Intl) is currently priced at $197.

What are the most reliable airlines from St. Louis to Washington, D.C. Dulles Intl Airport?

No one likes to see their flight delayed. When booking a flight from St. Louis to Washington, D.C. Dulles Intl Airport consider choosing Avianca (85%), Copa Airlines (85%) or Lufthansa (82%) as they are the most reliable in getting you off to your destination on time.

What are the most popular airlines that fly from St. Louis to Washington, D.C. Dulles Intl Airport?

American Airlines, Delta and United Airlines are the most popular airlines when flying from St. Louis to Washington, D.C. Dulles Intl Airport.

What airport do you fly from for flights from St. Louis to Washington, D.C. Dulles Intl?

Most people fly from Lambert-St Louis (STL) if they book a flight from St. Louis to Washington, D.C. Dulles Intl. On average, Lambert-St Louis has 6 outbound flights to Washington, D.C. Dulles Intl per day from 3 airlines. Lambert-St Louis is conveniently located just 12.7 mi from St. Louis’s city center.

Can I find deals for flights from St. Louis to Dulles Intl that include hotel bookings?

Yes. In addition to deals on St. Louis to Dulles Intl flights, Cheapflights offers vacation packages that include both flights and hotel.

How can I find direct flights from St. Louis to Dulles Intl?

After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from St. Louis to Dulles Intl.

Can I find deals for business class flights from St. Louis to Dulles Intl?

Yes. Cheapflights offers flight deals from St. Louis to Dulles Intl by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

$66+ Flights from St. Louis to Washington, D.C. Dulles Intl Airport

Q: How much does it cost to fly round-trip from St. Louis to Washington, D.C. Dulles Intl Airport?

Airfare is below average for this route at the moment. St. Louis to Washington, D.C. Dulles Intl Airport flights typically cost between $275 and $576 in October. The cheapest round-trip price found within the last 3 days was $184 on Frontier (Oct 16-Oct 23).

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Cheapflights Tip: The best prices from Lambert-St Louis to Washington, D.C. Dulles Intl are usually found in March or January, booked 75 days in advance, depart on a Friday or Tuesday and return on a Wednesday

Cheap flight deals from St. Louis to Dulles Intl

Round-trip from	$184 (Booking.com)
One-way from	$66 (United Airlines)
Popular in	July
Cheapest in	March
Average price	$315
Good round-trip deal	$590 or less
Good one-way deal	$405 or less

From Lambert-St Louis to Washington, D.C. Dulles Intl

Search Deals

One-way flight from Lambert-St Louis to Washington, D.C. Dulles Intl

Search Deals

Highest demand for flights based on searches. 5% potential increase in price ($19 potential increase over avg. RT price).

Search Deals

Cheapest flight prices on average. 3% potential price decrease ($12 potential savings vs. average RT price).

Search Deals

Average for round-trip flights in September 2025

Search Deals

Price to beat on a round-trip flight from Lambert-St Louis to Washington, D.C. Dulles Intl.

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Price to beat on a one-way flight from Lambert-St Louis to Washington, D.C. Dulles Intl.

Search Deals

Find flight deals from St. Louis to Dulles Intl

Cheapest flights from St. Louis to Dulles Intl
Explore the most affordable flight options available from St. Louis to Dulles Intl. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 17, 2025.

Thu 10/1611:32 amSTL - IAD

1 stop10h 57mFrontier

Thu 10/236:15 amIAD - STL

1 stop5h 22mFrontier

Deal found 9/16

$184

Sun 9/214:00 pmSTL - IAD

1 stop7h 15mFrontier

Mon 9/296:10 amIAD - STL

1 stop9h 54mFrontier

Deal found 9/16

$186

Wed 10/17:55 pmSTL - IAD

2 stops16h 00mFrontier

Sun 10/56:10 amIAD - STL

1 stop9h 54mFrontier

Deal found 9/16

$190

Tue 10/146:14 pmSTL - IAD

1 stop3h 46mDelta

Wed 10/156:05 amIAD - STL

1 stop4h 32mDelta

Deal found 9/14

$197

Fri 9/261:57 pmSTL - IAD

1 stop27h 27mFrontier

Mon 9/296:10 amIAD - STL

1 stop9h 54mFrontier

Deal found 9/16

$198

Fri 10/176:05 pmSTL - IAD

1 stop25h 48mFrontier

Sun 10/196:15 amIAD - STL

1 stop5h 22mFrontier

Deal found 9/15

$199

Fri 10/314:52 pmSTL - IAD

1 stop5h 37mFrontier

Mon 11/36:18 pmIAD - STL

2 stops39h 49mFrontier

Deal found 9/17

$202

Thu 9/2510:49 amSTL - IAD

2 stops12h 26mFrontier

Mon 9/296:10 amIAD - STL

1 stop9h 54mFrontier

Deal found 9/15

$204

Fri 10/314:52 pmSTL - IAD

1 stop5h 37mFrontier

Thu 11/69:52 pmIAD - STL

2 stops19h 09mFrontier

Deal found 9/17

$206

Thu 10/2310:17 amSTL - IAD

1 stop21h 52mFrontier

Sun 10/263:10 pmIAD - STL

2 stops19h 22mFrontier

Deal found 9/15

$208

Thu 9/2510:49 amSTL - IAD

2 stops12h 26mFrontier

Sun 9/286:10 amIAD - STL

1 stop9h 54mFrontier

Deal found 9/15

$209

Best flights from St. Louis to Dulles Intl
Discover carefully curated flight deals from St. Louis to Dulles Intl that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated September 17, 2025.

Tue 3/104:00 pmSTL - IAD

1 stop7h 07mDelta

Wed 3/111:00 pmIAD - STL

1 stop6h 04mDelta

Deal found 9/14

$197

Sat 11/13:59 pmSTL - IAD

1 stop6h 21mDelta

Sun 11/27:05 amIAD - STL

1 stop4h 26mDelta

Deal found 9/15

$197

Thu 11/611:36 amSTL - IAD

1 stop4h 21mDelta

Mon 11/105:59 pmIAD - STL

1 stop6h 41mDelta

Deal found 9/15

$197

Tue 12/235:55 pmSTL - IAD

1 stop4h 13mDelta

Wed 12/316:00 amIAD - STL

1 stop4h 24mDelta

Deal found 9/15

$197

Mon 10/271:30 pmSTL - IAD

1 stop7h 01mDelta

Tue 10/283:33 pmIAD - STL

1 stop7h 31mDelta

Deal found 9/15

$197

Fri 10/176:52 pmSTL - IAD

1 stop4h 20mDelta

Mon 10/207:35 pmIAD - STL

1 stop5h 06mDelta

Deal found 9/15

$277

Tue 10/76:14 pmSTL - IAD

1 stop3h 46mDelta

Tue 10/146:00 amIAD - STL

1 stop5h 26mDelta

Deal found 9/16

$277

Fri 11/149:21 amSTL - IAD

1 stop6h 43mDelta

Sun 11/237:01 amIAD - STL

1 stop6h 59mDelta

Deal found 9/15

$277

Tue 12/235:55 pmSTL - IAD

1 stop4h 13mDelta

Tue 12/3012:32 pmIAD - STL

1 stop5h 27mDelta

Deal found 9/17

$277

Fri 11/145:12 pmSTL - IAD

1 stop6h 06mDelta

Sun 11/166:00 amIAD - STL

1 stop5h 49mDelta

Deal found 9/16

$277

Wed 11/51:30 pmSTL - IAD

1 stop4h 56mDelta

Sat 11/89:00 amIAD - STL

1 stop6h 43mDelta

Deal found 9/16

$280

Last-minute flights from St. Louis to Dulles Intl
Discover last-minute flight deals from St. Louis to Dulles Intl. Data last updated September 17, 2025 and is based on user searches.

Sun 9/214:00 pmSTL - IAD

1 stop7h 15mFrontier

Mon 9/296:10 amIAD - STL

1 stop9h 54mFrontier

Deal found 9/16

$186

Thu 9/2510:49 amSTL - IAD

2 stops12h 26mFrontier

Mon 9/296:10 amIAD - STL

1 stop9h 54mFrontier

Deal found 9/15

$204

Thu 9/2510:49 amSTL - IAD

2 stops12h 26mFrontier

Sun 9/286:10 amIAD - STL

1 stop9h 54mFrontier

Deal found 9/15

$209

Fri 9/261:57 pmSTL - IAD

1 stop27h 27mFrontier

Mon 9/296:10 amIAD - STL

1 stop9h 54mFrontier

Deal found 9/17

$198

Wed 10/17:55 pmSTL - IAD

2 stops16h 00mFrontier

Sun 10/56:10 amIAD - STL

1 stop9h 54mFrontier

Deal found 9/16

$190

Tue 10/146:14 pmSTL - IAD

1 stop3h 46mDelta

Wed 10/156:05 amIAD - STL

1 stop4h 32mDelta

Deal found 9/14

$197

Thu 10/1611:32 amSTL - IAD

1 stop10h 57mFrontier

Thu 10/236:15 amIAD - STL

1 stop5h 22mFrontier

Deal found 9/16

$184

Fri 10/176:05 pmSTL - IAD

1 stop25h 48mFrontier

Sun 10/196:15 amIAD - STL

1 stop5h 22mFrontier

Deal found 9/15

$199

Thu 10/2310:17 amSTL - IAD

1 stop21h 52mFrontier

Sun 10/263:10 pmIAD - STL

2 stops19h 22mFrontier

Deal found 9/15

$208

Fri 10/314:52 pmSTL - IAD

1 stop5h 37mFrontier

Mon 11/36:18 pmIAD - STL

2 stops39h 49mFrontier

Deal found 9/17

$202

Fri 10/314:52 pmSTL - IAD

1 stop5h 37mFrontier

Thu 11/69:52 pmIAD - STL

2 stops19h 09mFrontier

Deal found 9/17

$206

One-way flights from St. Louis to Dulles Intl
Search for one-way flight options from St. Louis to Dulles Intl. Find affordable one-way fares based on user searches. Data last updated September 17, 2025.

Tue 11/181:10 pmSTL - IAD

Nonstop2h 07mUnited Airlines

Deal found 9/15

$66

Thu 10/3011:07 amSTL - IAD

1 stop4h 27mFrontier

Deal found 9/15

$72

Sun 9/281:52 pmSTL - IAD

1 stop27h 32mFrontier

Deal found 9/15

$78

Sun 10/51:57 pmSTL - IAD

1 stop27h 27mFrontier

Deal found 9/15

$79

Sat 11/158:25 amSTL - IAD

Nonstop2h 08mUnited Airlines

Deal found 9/15

$80

Thu 10/24:00 pmSTL - IAD

1 stop6h 39mFrontier

Deal found 9/17

$83

Wed 11/197:24 pmSTL - IAD

1 stop13h 53mFrontier

Deal found 9/16

$84

Wed 11/128:25 amSTL - IAD

Nonstop2h 08mUnited Airlines

Deal found 9/15

$85

Thu 10/2311:32 amSTL - IAD

1 stop10h 57mFrontier

Deal found 9/14

$89

Thu 10/911:32 amSTL - IAD

1 stop10h 57mFrontier

Deal found 9/17

$95

Sat 10/187:05 amSTL - IAD

1 stop6h 33mDelta

Deal found 9/14

$99

Thu 11/1311:07 amSTL - IAD

1 stop4h 27mFrontier

Deal found 9/16

$100

Cheapflights Fare Finder

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

Tue 3/10

4:00 pm-12:07 am

1 stop7h 07m

Washington, D.C. Dulles Intl

Wed 3/11

1:00 pm-6:04 pm

1 stop6h 04m

$197

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Sat 11/1

3:59 pm-11:20 pm

1 stop6h 21m

Washington, D.C. Dulles Intl

Sun 11/2

7:05 am-10:31 am

1 stop4h 26m

$197

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Thu 11/6

11:36 am-4:57 pm

1 stop4h 21m

Washington, D.C. Dulles Intl

Mon 11/10

5:59 pm-11:40 pm

1 stop6h 41m

$197

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 12/23

5:55 pm-11:08 pm

1 stop4h 13m

Washington, D.C. Dulles Intl

Wed 12/31

6:00 am-9:24 am

1 stop4h 24m

$197

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Mon 10/27

1:30 pm-9:31 pm

1 stop7h 01m

Washington, D.C. Dulles Intl

Tue 10/28

3:33 pm-10:04 pm

1 stop7h 31m

$197

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 10/17

6:52 pm-12:12 am

1 stop4h 20m

Washington, D.C. Dulles Intl

Mon 10/20

7:35 pm-11:41 pm

1 stop5h 06m

$277

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 10/7

6:14 pm-11:00 pm

1 stop3h 46m

Washington, D.C. Dulles Intl

Tue 10/14

6:00 am-10:26 am

1 stop5h 26m

$277

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Fri 11/14

9:21 am-5:04 pm

1 stop6h 43m

Washington, D.C. Dulles Intl

Sun 11/23

7:01 am-1:00 pm

1 stop6h 59m

$277

St. LouisWashington, D.C.

STL - IAD

STLIAD

Lambert-St Louis

Tue 12/23

5:55 pm-11:08 pm

1 stop4h 13m

Washington, D.C. Dulles Intl

Tue 12/30

12:32 pm-4:59 pm

1 stop5h 27m

$277

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 11/16

6:00 am-10:49 am

1 stop5h 49m

$277

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/15

Showing 1-10 of 21 results

The best insider tips for St. Louis to Washington, D.C. Dulles Intl Airport flights

Cheapflights partnered with top experts to bring you the best recommendations for your St. Louis to Washington, D.C. Dulles Intl Airport trip

Airports

STL

Expect security screening at STL to take 5-10 minutes during off-peak times. Check real-time wait times online before heading to the airport.

IAD

The Washington Metro Silver Line reaches IAD in under 40 minutes, offering a cheap and convenient way to get to the airport.

Our travel experts

Taryn White

Expert on STL

Ramsey Qubein

Expert on IAD

Best time to book a flight from St. Louis to Dulles Intl

Have a flexible travel schedule? Discover the best time to fly to Dulles Intl from St. Louis with our price prediction graph.

Estimated round-trip price

Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from St. Louis to Washington, D.C. Dulles Intl Airport

Prices

Airlines

How far ahead should I book a flight from St. Louis to Washington, D.C. Dulles Intl Airport?

The best time to book flights from St. Louis to Washington, D.C. Dulles Intl Airport is 75 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.

What is the cheapest month to book a flight from St. Louis to Washington, D.C. Dulles Intl Airport?

Currently, August is the cheapest month in which you can book a flight from St. Louis to Washington, D.C. Dulles Intl Airport (average of $292). Flying from St. Louis to Washington, D.C. Dulles Intl Airport in April is currently the most expensive (average of $337). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from STL to IAD?

It’s optimal to fly from St. Louis to Washington, D.C. Dulles Intl Airport in the evening. By choosing this option you can save up to 78% on the cost of your flight, compared to a flight at noon.

How much does it cost to fly round-trip from St. Louis to Washington, D.C. Dulles Intl Airport?

Reviews of airlines servicing Dulles Intl

Peruse reviews from past customers who have flown with Delta, United Airlines, and American Airlines from St. Louis to Washington, D.C. Dulles Intl Airport to help guide your decision. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.

Delta

8.0

Very good

7,961 reviews

Reviews

1 / 20

10.0

Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!

Delta

8.0

Very good

7,961 reviews

Delta

8.0

Very good

7,961 reviews

Reviews

1 / 20

10.0

Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!

United Airlines

7.4

Good

8,926 reviews

Delta

8.0

Very good

7,961 reviews

Reviews

1 / 20

10.0

Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!

American Airlines

7.2

Good

10,000 reviews

Delta

8.0

Very good

7,961 reviews

Reviews

1 / 20

10.0

Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!

Related info for your journey

What airport do you fly from for flights from St. Louis to Washington, D.C. Dulles Intl?
Most people fly from Lambert-St Louis (STL) if they book a flight from St. Louis to Washington, D.C. Dulles Intl. On average, Lambert-St Louis has 6 outbound flights to Washington, D.C. Dulles Intl per day from 3 airlines. Lambert-St Louis is conveniently located just 12.7 mi from St. Louis’s city center.
How long is the flight from St. Louis to Washington, D.C. Dulles Intl Airport?
A quick flight from St. Louis to Washington, D.C. Dulles Intl Airport can take about 7h 07m. Delta provides one of the quickest options available for as low as $197. There are 694 mi between St. Louis and Washington, D.C. Dulles Intl Airport.
What are the cheapest airlines flying from St. Louis to Washington, D.C. Dulles Intl Airport round-trip?
Currently priced at $129, American Airlines will fly you from St. Louis to Washington, D.C. Dulles Intl Airport and back. In addition to American Airlines, many other airlines offer competitively priced options for your trip. Search Cheapflights for deals from Delta and United Airlines - these airlines can fly you to your destination from $168 and $211, respectively. American Airlines is 65% cheaper than the average price of flights available within the next 90 days to this destination.
What are the most reliable airlines from St. Louis to Washington, D.C. Dulles Intl Airport?
No one likes to see their flight delayed. When booking a flight from St. Louis to Washington, D.C. Dulles Intl Airport consider choosing Avianca (85%), Copa Airlines (85%) or Lufthansa (82%) as they are the most reliable in getting you off to your destination on time.
What are the cheapest flights from St. Louis to Washington, D.C. Dulles Intl Airport?
On average you can expect to pay $1,362 for a flight from St. Louis to Washington, D.C. Dulles Intl Airport. The cheapest flight overall is $138 while the most popular route, (Lambert-St Louis - Washington, D.C. Dulles Intl) is currently priced at $197.
Can I find deals for flights from St. Louis to Dulles Intl that include hotel bookings?
Yes. In addition to deals on St. Louis to Dulles Intl flights, Cheapflights offers vacation packages that include both flights and hotel.
How can I find direct flights from St. Louis to Dulles Intl?
After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from St. Louis to Dulles Intl.
Can I find deals for business class flights from St. Louis to Dulles Intl?
Yes. Cheapflights offers flight deals from St. Louis to Dulles Intl by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.
What is the cheapest month to book a flight from St. Louis to Washington, D.C. Dulles Intl Airport?
Currently, August is the cheapest month in which you can book a flight from St. Louis to Washington, D.C. Dulles Intl Airport (average of $292). Flying from St. Louis to Washington, D.C. Dulles Intl Airport in April is currently the most expensive (average of $337). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

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Top 3 airlines flying from St. Louis to Dulles Intl

Airline	Cheapest	Average	Flexibility	On-time
American Airlines	Cheapest$129	Average$315	FlexibilityNo cancel fee	On-time71%
Delta	Cheapest$168	Average$265	FlexibilityNo cancel fee	On-timeN/A
United Airlines	Cheapest$211	Average$444	FlexibilityNo cancel fee	On-time69%

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$66+ Cheap flights from St. Louis (STL) to Dulles Intl (IAD)

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 11/18. Fares are subject to change and may not be available on all flights or dates of travel.

Find cheap flights from St. Louis to Dulles Intl with Cheapflights

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3. Compare prices and book

Cheapflights Tip: The best prices from Lambert-St Louis to Washington, D.C. Dulles Intl are usually found in March or January, booked 75 days in advance, depart on a Friday or Tuesday and return on a Wednesday

Cheap flight deals from St. Louis to Dulles Intl

Round-trip from

One-way from

Popular in

Cheapest in

Average price

Good round-trip deal

Good one-way deal

Find flight deals from St. Louis to Dulles Intl

Cheapest flights from St. Louis to Dulles IntlExplore the most affordable flight options available from St. Louis to Dulles Intl. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 17, 2025.

Explore the most affordable flight options available from St. Louis to Dulles Intl. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 17, 2025.

Cheapflights Fare Finder

Use the filters below to find and compare flights from St. Louis to Washington, D.C. Dulles Intl Airport that are best for you.

The best insider tips for St. Louis to Washington, D.C. Dulles Intl Airport flights

Cheapflights partnered with top experts to bring you the best recommendations for your St. Louis to Washington, D.C. Dulles Intl Airport trip

Airports

STL

IAD

Our travel experts

Best time to book a flight from St. Louis to Dulles Intl

Have a flexible travel schedule? Discover the best time to fly to Dulles Intl from St. Louis with our price prediction graph.

Cheapflights Insights

Everything you need to know about your flight from St. Louis to Washington, D.C. Dulles Intl Airport

How far ahead should I book a flight from St. Louis to Washington, D.C. Dulles Intl Airport?

What is the cheapest month to book a flight from St. Louis to Washington, D.C. Dulles Intl Airport?

What is the cheapest time of day to fly from STL to IAD?

How much does it cost to fly round-trip from St. Louis to Washington, D.C. Dulles Intl Airport?

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Cheapest flights from St. Louis to Dulles Intl
Explore the most affordable flight options available from St. Louis to Dulles Intl. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 17, 2025.