Seattle to St Louis flights

Routavio compares airline fares from several flight booking sites. The lowest one-way fare it found for Seattle to St Louis is €99 with United Airlines (checked on 17 Oct 2026).

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Lowest observed

€99

Average observed

€138

Cheapest month

November 2026

Last checked

24 Oct 2026

Observed fares. Prices may change.

Your next trip, last seen at €99

Lowest observed

18 Nov 2026

United Airlines · 1 stop · One way

Cheapest observed day · Last checked: 17 Oct 2026

Departure

22:56

When to fly

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One-way fare

One-way fare · No data: click and we will search

Lowest observed: €99, departing 18 Nov 2026 (Last checked: 17 Oct 2026)One-way fareCheck live prices for this route
Airlines seen: Alaska Airlines, Southwest Airlines, Frontier Airlines, United Airlines
Reported fastest flight: 3h 51m
Non-stop: Yes

Short answer

Routavio has seen Alaska Airlines fares from Seattle to St Louis, non-stop. The lowest fare Routavio's own searches returned is €99, seen on 17 Oct 2026. The average across the fares we caught is €138. November 2026 is the cheapest month in our observations, at €99. These are prices Routavio's searches returned on the dates shown, not quotes; run a live search for today's fare.

About this route

Explore the fares we observed from Seattle to St Louis. Prices move often, so pick your dates to see the latest options.

Route distance: 2,768 km
Reported fastest flight: 3h 51m
Alternative airports: BFI, SUS

Route-level information; individual journeys vary.
Published schedules report non-stop service with Alaska Airlines, Southwest Airlines. Check current timetables.

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Observed, not guaranteed

Every price is a fare we actually saw, and it may change at any time.

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How our prices work

Non-stop airlines seen on this route

Non-stop airlines seen on this route
Airline	Non-stop days / priced days	Fastest non-stop
Alaska Airlines	13 / 81

Departure days with a non-stop fare checked in the last 14 days. A carrier listed here had a non-stop fare on at least 3 days; schedules may differ.

Airport to city: straight-line distance

King County International Airport - Boeing Field (BFI) → Seattle, city gazetteer reference point (47.6062, -122.3321): ≈ 9 km.
Seattle–Tacoma International Airport (SEA) → Seattle, city gazetteer reference point (47.6062, -122.3321): ≈ 18 km.
St. Louis Lambert International Airport (STL) → St Louis, city gazetteer reference point (38.6270, -90.1994): ≈ 20 km.

Approximate distances calculated from coordinates, not road distances or travel times. These airports serve the city; they are not confirmed endpoints of an offer.

Lowest one-way fare we saw per airline

Cheapest airline from Seattle to St Louis: United Airlines, from €99 (checked 17 Oct 2026).

Lowest one-way fare we saw per airline
Airline	Lowest fare	Priced days
United Airlines	€99Nov 18, 2026	58
Frontier Airlines	€145Nov 6, 2026	9
Alaska Airlines	€161Nov 11, 2026	14

One-way fares checked in the last 14 days. An airline listed here had a fare on at least 3 departure days. Each figure is the lowest we saw, not a guaranteed fare. Connecting itineraries are included; the date is the departure day of that fare.

Frequently asked

How much is a flight from Seattle to St Louis?

The lowest fare Routavio has observed is €99, found on 17 Oct 2026. Prices move, so read it as a floor rather than a quote.

When is the cheapest month to fly from Seattle to St Louis?

In our observations November 2026 is the cheapest month so far, at €99.

Are there direct flights from Seattle to St Louis?

Yes. Published schedules report non-stop flights on this route with Alaska Airlines, Southwest Airlines.

Which airlines fly from Seattle to St Louis?

Routavio has seen these carriers on the route: Alaska Airlines, Southwest Airlines, Frontier Airlines, United Airlines.

How long does the flight from Seattle to St Louis take?

Across the 87 fares Routavio observed, the average journey time is 9h 01m, including any stops. Individual departures vary; the fastest observed flight is listed in the route facts above.

How many of the observed Seattle to St Louis fares were non-stop?

16 of the 87 fares we observed were non-stop; the rest included at least one stop. That describes our observations, not every flight that operates.

Which airlines had non-stop offers on at least 3 departure dates from Seattle to St Louis?

For Seattle to St Louis, examples of observed one-way non-stop offers checked within the last 14 days: Alaska Airlines (13). Each number counts distinct departure dates, not weekly flights; check current availability in search.

Which airline has the lowest fare from Seattle to St Louis?

Cheapest airline from Seattle to St Louis: United Airlines, from €99 (checked 17 Oct 2026).

How observed prices work, what "No data" means and what a fare includes: Read the flight price guide