$77 Cheap Flights from St. Louis (STL) to Washington (IAD)

View $77 flight on Mon, Oct 6, 2025Opens in a new window

Popular airlines from St. Louis Lambert Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD)

    notification illustration

    Be in the know

    Get alerts if flight prices drop or rise*
    deals illustration

    Book smarter

    Save up to 30% on select hotels after you book a flight*
    trophy illustration

    Earn twice

    Earn your airline miles on top of our OneKeyCash
    Learn about One Key

Cheap Flights from St. Louis to Washington (STL-IAD)

Prices were available within the past 7 days and start at $77 for one-way flights and $154 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Frontier Airlines
Mon, Oct 6 - Thu, Oct 9
STL
St. Louis
IAD
Washington
$154 Roundtrip, found 1 hour ago
$154
Roundtrip
found 1 hour ago
Select Frontier Airlines flight, departing Mon, Oct 6 from St. Louis to Washington, returning Thu, Oct 9, priced at $154 found 1 hour ago
Frontier Airlines
Fri, Oct 10 - Sun, Oct 12
STL
St. Louis
IAD
Washington
$176 Roundtrip, found 1 hour ago
$176
Roundtrip
found 1 hour ago
Select Frontier Airlines flight, departing Fri, Oct 10 from St. Louis to Washington, returning Sun, Oct 12, priced at $176 found 1 hour ago
Frontier Airlines
Fri, Nov 7 - Sun, Nov 9
STL
St. Louis
IAD
Washington
$183 Roundtrip, found 1 hour ago
$183
Roundtrip
found 1 hour ago
Select Frontier Airlines flight, departing Fri, Nov 7 from St. Louis to Washington, returning Sun, Nov 9, priced at $183 found 1 hour ago
Frontier Airlines
Thu, Nov 6 - Fri, Nov 7
STL
St. Louis
IAD
Washington
$196 Roundtrip, found 5 days ago
$196
Roundtrip
found 5 days ago
Select Frontier Airlines flight, departing Thu, Nov 6 from St. Louis to Washington, returning Fri, Nov 7, priced at $196 found 5 days ago
Frontier Airlines
Fri, Oct 3 - Thu, Oct 9
STL
St. Louis
IAD
Washington
$196 Roundtrip, found 1 hour ago
$196
Roundtrip
found 1 hour ago
Select Frontier Airlines flight, departing Fri, Oct 3 from St. Louis to Washington, returning Thu, Oct 9, priced at $196 found 1 hour ago
Delta
Wed, Oct 22 - Sun, Nov 2
STL
St. Louis
IAD
Washington
$202 Roundtrip, found 6 hours ago
$202
Roundtrip
found 6 hours ago
Select Delta flight, departing Wed, Oct 22 from St. Louis to Washington, returning Sun, Nov 2, priced at $202 found 6 hours ago
Frontier Airlines
Thu, Oct 9 - Sun, Oct 12
STL
St. Louis
IAD
Washington
$207 Roundtrip, found 1 hour ago
$207
Roundtrip
found 1 hour ago
Select Frontier Airlines flight, departing Thu, Oct 9 from St. Louis to Washington, returning Sun, Oct 12, priced at $207 found 1 hour ago
United
Wed, Oct 29 - Sun, Nov 16
STL
St. Louis
IAD
Washington
$221 Roundtrip, found 3 days ago
$221
Roundtrip
found 3 days ago
Select United flight, departing Wed, Oct 29 from St. Louis to Washington, returning Sun, Nov 16, priced at $221 found 3 days ago
Southwest Airlines
Wed, Nov 5 - Sun, Nov 9
STL
St. Louis
IAD
Washington
$227 Roundtrip, found 5 days ago
$227
Roundtrip
found 5 days ago
Select Southwest Airlines flight, departing Wed, Nov 5 from St. Louis to Washington, returning Sun, Nov 9, priced at $227 found 5 days ago
American Airlines
Tue, Dec 2 - Tue, Dec 9
STL
St. Louis
IAD
Washington
$261 Roundtrip, found 2 days ago
$261
Roundtrip
found 2 days ago
Select American Airlines flight, departing Tue, Dec 2 from St. Louis to Washington, returning Tue, Dec 9, priced at $261 found 2 days ago

Find the cheapest month to fly from St. Louis (STL) to Washington (IAD)

February is typically the cheapest month to fly

From $149 - $603 per traveler.

Alternative airports near Washington

Prices were available within the past 7 days. Prices and availability are subject to change.

Select flight to Ronald Reagan Washington National DCA. Closest option available. Average driving time to city center is 8 minutes. Flights from $449
DCA
Ronald Reagan Washington National
Closest
Average driving time to city center8 min
Flights from $449
Flights from St. Louis (STL) to Washington (IAD)
Origin airport
Lambert-St. Louis Intl.
Destination airport
Washington Dulles Intl.
Airlines serving
American Airlines, Delta, Frontier Airlines, Southwest Airlines, United
Roundtrip price
$154
Distance
694 mi
Average flight time
3 hours 10 mins

St. Louis to Washington Flights

The cheapest times to fly from St. Louis to Washington

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from St. Louis to Washington are during the month of October. You can find some of the cheapest flights from St. Louis to Washington with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from St. Louis to Washington

Sunday is one of the best days to book for cheap flights from St. Louis to Washington: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

 

How to find cheap round-trip tickets from St. Louis to Washington

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from St. Louis to Washington in 2025. You can also book with separate airlines for your outbound and return journeys, from $77 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

 

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap St. Louis to Washington flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

 

You could also save big by booking one of Expedia's vacation packages. Bundling together your St. Louis to Washington airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

 

*Terms apply.

 

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

 

Frequently asked questions

How much does a flight from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD) cost?
Snag a cheap one-way flight from $77 or cheap return flight from $154 from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to see our cheapest flight offers on this route.
What is the cheapest month to fly from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD)?
The cheapest month to fly from STL to IAD is October, when demand is low. Off-peak months are generally when you'll find lower airfares between these airports.
Which airlines fly direct from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD)?
Jump on a direct flight with United Airlines and fly straight from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD).
What is the cheapest airline that flies from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD)?
To find the cheapest airline flying from STL to IAD, use Expedia's filter tool. Tailor your search based on what matters most to you, such as preferred carriers and ideal departure window. You can then sort your results by "Price (lowest to highest)" to see the most affordable options first.
How many flights per day from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD)?
When flying out of Lambert-St. Louis Intl. Airport (STL), you'll have a choice from an average of 2 daily nonstop flights to Washington Dulles Intl. Airport (IAD).
What are the most popular departure times for flights from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD)?
Flights between STL and IAD are busiest at 8 AM. If you'd like a more relaxed atmosphere and potentially cheaper prices, choose a departure that's outside typical rush times.
What day of the week has the most flights from STL to IAD?
Depart on a Friday if you're after the biggest selection of flights from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD).
What is the earliest flight from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD)?
The earliest flight jetting off from Lambert-St. Louis Intl. Airport (STL) is at around 8:15AM UTC-6. Board this plane and you'll reach Washington Dulles Intl. Airport (IAD) at approximately 11:33AM UTC-5. The total time in the air is 2h 18m.
How long does it take to fly from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD)?
The average flight time from STL to IAD is 2 hours and 13 minutes, covering a total distance of 700 mi.
What airline has the least delays from STL to IAD?
With 88% of flights typically arriving as scheduled, United Airlines has the best on-time performance for direct flights from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD). To monitor your flight status and get notified if anything changes, use the Expedia App.
What is the best time to fly from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD)?
To touch down at Washington Dulles Intl. Airport (IAD) on schedule, opt for a flight that leaves Lambert-St. Louis Intl. Airport (STL) before 3 PM. The likelihood of cancellations is 22% higher, on average, for departures after this time.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
What airports do you fly into for Washington from Lambert-St. Louis Intl. Airport (STL)?
You can land at one of these Washington airports after your direct flight from Lambert-St. Louis Intl. Airport (STL):

  • Ronald Reagan Washington National Airport (DCA)
  • Washington Dulles Intl. Airport (IAD)
  • Baltimore Washington Intl. Thurgood Marshall Airport (BWI)

Is it cheaper to buy a plane ticket from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD) last-minute?
Last-minute bookings from STL to IAD are usually more expensive. To secure the best prices, start searching for flights ahead of time. That said, if you're flexible with your travel dates, you may find a cheap fare right before you leave.
Is it cheaper to book a STL to IAD flight and hotel package?
You'll generally save money by booking a STL to IAD flight and hotel package compared to booking separately. In fact, you could save hundreds of dollars by bundling with Expedia. And it's easy to manage everything in one convenient place. After selecting your ideal accommodations and flights, consider other add-ons like car rentals, tours and activities.
Can I cancel or change the date of my flight from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD)?
If you booked your STL to IAD flight within the last 24 hours, you may be able to modify or cancel it at no cost. Depending on the airline and the ticket type you purchased, additional charges may apply for changes after that time. Airline policies and contact information can be found in your itinerary or confirmation email. Or, go to our Customer Service portal if you'd like more information.

Explore a world of travel with Expedia

*Available to One Key members.