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St Louis to Seattle Flights — Fares from $245.00 | STL–SEA

Compare the cheapest St Louis (STL) to Seattle (SEA) fares found by our live flight search, then book online or over the phone with our travel experts.

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Adults
12+
1
Children
2–11
0
Infants
Under 2
0
Cabin
🏷️
Save up to 40% with unpublished phone fares
Consolidator deals on selected St Louis → Seattle flights that do not appear in online search results. The live fares below are bookable right now — or call to check for an unpublished fare on your dates.
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One-way fares St Louis → Seattle

showing indicative fares · loading live prices…
Delta Air Lines
Delta Air Lines CHEAPEST
STL → SEA · Economy
lowest fare seen on this route
$408.80
$245.28
Select
American Airlines
American Airlines
STL → SEA · Economy
lowest fare seen on this route
$482.00
$289.20
Select
Alaska Airlines
Alaska Airlines
STL → SEA · Economy
lowest fare seen on this route
$536.80
$322.08
Select
United Airlines
United Airlines
STL → SEA · Economy
lowest fare seen on this route
$594.00
$356.40
Select
Southwest
Southwest
STL → SEA · Economy
lowest fare seen on this route
$624.00
$374.40
Select
Frontier
Frontier
STL → SEA · Economy
lowest fare seen on this route
$1,346.00
$807.60
Select
See all flights & times → Prices per adult, one way, incl. taxes & fees. Availability changes constantly.
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Live fares we can book on STL–SEA

Lowest fare found per airline on the STL → SEA route, with our discounted phone-deal price.

AirlineCabin Found fareOur discounted fare Fare found on
Delta Air Lines Delta Air Lines Economy $408.80 $245.28 Aug 14, 2026 Book
American Airlines American Airlines Economy $482.00 $289.20 Aug 14, 2026 Book
Alaska Airlines Alaska Airlines Economy $536.80 $322.08 Aug 14, 2026 Book
United Airlines United Airlines Economy $594.00 $356.40 Aug 14, 2026 Book
Southwest Southwest Economy $624.00 $374.40 Aug 14, 2026 Book
Frontier Frontier Economy $1,346.00 $807.60 Aug 14, 2026 Book

Discounted fares are negotiated phone deals from our vendor network and may not appear in online search results — call 765-995-0868 to lock one in. Fares were found on the dates shown, are per person in USD, and change with availability.

More routes we cover

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Page updated August 16, 2026 · fare data refreshed automatically from live flight searches.