Cheap Flights from Washington (IAD) to St. Louis (CPS)

Popular airlines from Washington Dulles Intl. Airport (IAD) to St. Louis, MO (CPS-St. Louis Downtown)

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Alternative airports near St. Louis

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

Select flight to Lambert-St. Louis Intl. STL. Cheapest option available. Average driving time to city center is 20 minutes. Flights from $571
STL
Lambert-St. Louis Intl.
Cheapest
Average driving time to city center20 min
Flights from $571

Frequently asked questions

How much does a flight from Washington Dulles Intl. Airport (IAD) to St. Louis Downtown Airport (CPS) cost?
Snag a cheap one-way flight or cheap return flight from Washington Dulles Intl. Airport (IAD) to St. Louis Downtown Airport (CPS) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to see our cheapest flight deals on this route.
What is the cheapest month to fly from Washington Dulles Intl. Airport (IAD) to St. Louis Downtown Airport (CPS)?
The cheapest month to fly from IAD to CPS is , when demand is low. Off-peak months are generally when you'll find cheap fares for travel between these airports.
What is the cheapest airline that flies from Washington Dulles Intl. Airport (IAD) to St. Louis Downtown Airport (CPS)?
Expedia's filter tool lets you easily compare different airlines, departure times and fares all in one place. Customize the search to your preferences, then sort by "Price (lowest to highest)" to find out which carrier offers the cheapest IAD to CPS flight.
How many flights per day from Washington Dulles Intl. Airport (IAD) to St. Louis Downtown Airport (CPS)?
Direct flights from Washington Dulles Intl. Airport (IAD) to St. Louis Downtown Airport (CPS) aren't available daily, so you'll need to take a flight with a layover. Explore your options with Expedia's filters. Enter your travel dates and pick either "1 Stop" or "2+ Stops."
What day of the week has the most flights from IAD to CPS?
You'll typically find Tuesday the quietest day for flights, while Fridays are often the busiest.* However this can vary from season to season and during peak travel times or public holidays.*Busiest/quietest day to travel is based on Expedia flight demand through January to December 2024.
What is the best time to fly from Washington Dulles Intl. Airport (IAD) to St. Louis Downtown Airport (CPS)?
To avoid possible delays on the Washington Dulles Intl. Airport (IAD) to St. Louis Downtown Airport (CPS) route, travel before 3 PM. Flights after this time are 22% more likely to be canceled.**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 East St. Louis from Washington Dulles Intl. Airport (IAD)?
Explore your flight options from Washington Dulles Intl. Airport (IAD) to Lambert-St. Louis Intl. Airport (STL). This is the only airport in East St. Louis you can fly into if you're taking a direct flight.
Is it cheaper to buy a plane ticket from Washington Dulles Intl. Airport (IAD) to St. Louis Downtown Airport (CPS) last-minute?
Waiting until right before your break to book your flight from IAD to CPS generally means paying more. While it's possible to find some last-minute deals, they're not always guaranteed. Allow some flexibility in your schedule for the best chance of snagging a bargain.
Is it cheaper to book an IAD to CPS flight and hotel package?
Compared with arranging flights and hotels separately, booking an IAD to CPS flight and hotel package with Expedia could lead to significant savings. Better still, having everything in one place takes the hassle out of travel planning. Simply pick your flights and choose from our extensive range of hotels, then tailor your trip with extras like activities, tours and car rentals.
Can I cancel or change the date of my flight from Washington Dulles Intl. Airport (IAD) to St. Louis Downtown Airport (CPS)?
In most cases, you're able to reschedule or cancel your IAD to CPS flight. However, there may be additional charges, especially if you made your booking more than 24 hours ago. Double-check your itinerary for the airline's fees and guidelines on flight changes, or if you'd like more information, head to our Customer Service portal.

Travel information

Origin airport
Washington Dulles Intl.
Destination airport
St. Louis Downtown
Distance
684 mi

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Washington to St. Louis Flights

The cheapest times to fly from Washington to St. Louis

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 Washington to St. Louis are during the month of . You can find some of the cheapest flights from Washington to St. Louis with Expedia's search tool and vast selection of airlines.

 

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

Sunday is one of the best days to book for cheap flights from Washington to St. Louis: 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 Washington to St. Louis

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 Washington to St. Louis in 2025. You can also book with separate airlines for your outbound and return journeys, from 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 Washington to St. Louis 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 Washington to St. Louis 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.

 

Washington to St. Louis Flights

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