$459 Cheap Flights from St. Louis (STL) to Seattle (BFI)

View $459 flight on Sat, Sep 13, 2025Opens in a new window

Popular airlines from St. Louis Lambert Intl. Airport (STL) to Seattle, WA (BFI-Boeing Field)

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Cheap Flights from St. Louis to Seattle (STL-BFI)

Prices were available within the past 7 days and start at $459 for one-way flights and $1,007 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Alaska Airlines
Sat, Sep 13 - Sun, Sep 21
STL
St. Louis
BFI
Seattle
$1,007 Roundtrip, found 6 days ago
$1,007
Roundtrip
found 6 days ago
Select Alaska Airlines flight, departing Sat, Sep 13 from St. Louis to Seattle, returning Sun, Sep 21, priced at $1,007 found 6 days ago
Alaska Airlines
Sat, Sep 13 - Sun, Sep 21
STL
St. Louis
BFI
Seattle
$1,057 Roundtrip, found 6 days ago
$1,057
Roundtrip
found 6 days ago
Select Alaska Airlines flight, departing Sat, Sep 13 from St. Louis to Seattle, returning Sun, Sep 21, priced at $1,057 found 6 days ago
Alaska Airlines
Sat, Sep 13 - Sun, Sep 21
STL
St. Louis
BFI
Seattle
$1,075 Roundtrip, found 6 days ago
$1,075
Roundtrip
found 6 days ago
Select Alaska Airlines flight, departing Sat, Sep 13 from St. Louis to Seattle, returning Sun, Sep 21, priced at $1,075 found 6 days ago
Alaska Airlines
Sat, Sep 13 - Sun, Sep 21
STL
St. Louis
BFI
Seattle
$1,125 Roundtrip, found 6 days ago
$1,125
Roundtrip
found 6 days ago
Select Alaska Airlines flight, departing Sat, Sep 13 from St. Louis to Seattle, returning Sun, Sep 21, priced at $1,125 found 6 days ago
Alaska Airlines
Wed, Aug 13 - Wed, Aug 20
STL
St. Louis
BFI
Seattle
$1,257 Roundtrip, found 1 day ago
$1,257
Roundtrip
found 1 day ago
Select Alaska Airlines flight, departing Wed, Aug 13 from St. Louis to Seattle, returning Wed, Aug 20, priced at $1,257 found 1 day ago
Alaska Airlines
Fri, Aug 29 - Mon, Sep 1
STL
St. Louis
BFI
Seattle
$1,322 Roundtrip, found 6 days ago
$1,322
Roundtrip
found 6 days ago
Select Alaska Airlines flight, departing Fri, Aug 29 from St. Louis to Seattle, returning Mon, Sep 1, priced at $1,322 found 6 days ago
Alaska Airlines
Wed, Aug 13 - Wed, Aug 20
STL
St. Louis
BFI
Seattle
$1,327 Roundtrip, found 1 day ago
$1,327
Roundtrip
found 1 day ago
Select Alaska Airlines flight, departing Wed, Aug 13 from St. Louis to Seattle, returning Wed, Aug 20, priced at $1,327 found 1 day ago
Alaska Airlines
Fri, Aug 29 - Mon, Sep 1
STL
St. Louis
BFI
Seattle
$1,350 Roundtrip, found 6 days ago
$1,350
Roundtrip
found 6 days ago
Select Alaska Airlines flight, departing Fri, Aug 29 from St. Louis to Seattle, returning Mon, Sep 1, priced at $1,350 found 6 days ago
Alaska Airlines
Fri, Aug 29 - Mon, Sep 1
STL
St. Louis
BFI
Seattle
$1,392 Roundtrip, found 6 days ago
$1,392
Roundtrip
found 6 days ago
Select Alaska Airlines flight, departing Fri, Aug 29 from St. Louis to Seattle, returning Mon, Sep 1, priced at $1,392 found 6 days ago
Alaska Airlines
Fri, Aug 29 - Mon, Sep 1
STL
St. Louis
BFI
Seattle
$1,404 Roundtrip, found 6 days ago
$1,404
Roundtrip
found 6 days ago
Select Alaska Airlines flight, departing Fri, Aug 29 from St. Louis to Seattle, returning Mon, Sep 1, priced at $1,404 found 6 days ago
Alaska Airlines
Fri, Aug 15 - Sun, Aug 17
STL
St. Louis
BFI
Seattle
$1,529 Roundtrip, found 5 days ago
$1,529
Roundtrip
found 5 days ago
Select Alaska Airlines flight, departing Fri, Aug 15 from St. Louis to Seattle, returning Sun, Aug 17, priced at $1,529 found 5 days ago
Alaska Airlines
Fri, Aug 15 - Sun, Aug 17
STL
St. Louis
BFI
Seattle
$1,736 Roundtrip, found 5 days ago
$1,736
Roundtrip
found 5 days ago
Select Alaska Airlines flight, departing Fri, Aug 15 from St. Louis to Seattle, returning Sun, Aug 17, priced at $1,736 found 5 days ago

Alternative airports near Seattle

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

Select flight to Seattle - Tacoma Intl. SEA. Cheapest option available. Average driving time to city center is 20 minutes. Flights from $351
SEA
Seattle - Tacoma Intl.
Cheapest
Average driving time to city center20 min
Flights from $351
Select flight to Snohomish County - Paine Field PAE. Average driving time to city center is 29 minutes. Flights from $7,738
PAE
Snohomish County - Paine Field
Average driving time to city center29 min
Flights from $7,738
Flights from St. Louis (STL) to Seattle (BFI)
Origin airport
Lambert-St. Louis Intl.
Destination airport
Boeing Field
Roundtrip price
$1,007
Distance
1706 mi

St. Louis to Seattle Flights

The cheapest times to fly from St. Louis to Seattle

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

 

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

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

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 Seattle in 2025. You can also book with separate airlines for your outbound and return journeys, from $459 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 Seattle 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 Seattle 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 Boeing Field Airport (BFI) cost?
Snag a cheap one-way flight from $459 or cheap return flight from $1,007 from Lambert-St. Louis Intl. Airport (STL) to Boeing Field Airport (BFI) 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 Boeing Field Airport (BFI)?
The cheapest month to fly from STL to BFI is September, when there's less demand. Off-peak season is usually when airlines offer better prices between these airports.
What is the cheapest airline that flies from Lambert-St. Louis Intl. Airport (STL) to Boeing Field Airport (BFI)?
Use the filters on Expedia to compare different airlines and find the most affordable carrier that'll fly you from STL to BFI. Then, sort your results by "Price (lowest to highest)" to pick up the best deal available.
How many flights per day from Lambert-St. Louis Intl. Airport (STL) to Boeing Field Airport (BFI)?
There are no daily direct flights departing from Lambert-St. Louis Intl. Airport (STL) to Boeing Field Airport (BFI). But you can choose flights with layovers. Filter your search on Expedia to include one or more stops, and you'll be cruising above the clouds before you know it.
What day of the week has the most flights from STL to BFI?
Friday is generally the busiest day for flights, while Tuesday tends to be the quietest.* Remember that flight schedules can vary based on a number of factors, including the airline and season.*Busiest/quietest day to travel is based on Expedia flight demand through January to December 2024.
What is the best time to fly from Lambert-St. Louis Intl. Airport (STL) to Boeing Field Airport (BFI)?
To arrive at Boeing Field Airport (BFI) on time, choose 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 Seattle from Lambert-St. Louis Intl. Airport (STL)?
Browse your flight options from Lambert-St. Louis Intl. Airport (STL) to Seattle - Tacoma Intl. Airport (SEA). This is the only Seattle airport you can jet into if you're taking a direct flight.
Is it cheaper to buy a plane ticket from Lambert-St. Louis Intl. Airport (STL) to Boeing Field Airport (BFI) last-minute?
Last-minute fares from STL to BFI are generally more expensive. To lock in the lowest prices, start searching for flights as early as possible. That being said, if your travel plans are flexible, it's possible to land a cheap ticket right before your trip.
Is it cheaper to book a STL to BFI flight and hotel package?
Compared with arranging hotels and flights separately, booking a STL to BFI flight and hotel package with Expedia could lead to significant savings. Better yet, having everything in one place takes the hassle out of planning your trip. Just secure your flights and choose from our wide range of stays, then tailor your trip with extras like tours and car rentals.
Can I cancel or change the date of my flight from Lambert-St. Louis Intl. Airport (STL) to Boeing Field Airport (BFI)?
In most instances, you're able to cancel or reschedule your STL to BFI flight. However, there may be additional charges, especially if you made your booking over 24 hours ago. Check your itinerary for the airline's policies and fees on flight changes, or if you want more information, visit our Customer Service portal.

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*Available to One Key members.