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Cheap Flights from St Louis to Denver (STL to DEN) from $29.00

Compare the cheapest St Louis (STL) to Denver (DEN) 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Save up to 40% with unpublished phone fares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 → Denver 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 The live fares below are bookable right now — or call to check for an unpublished fare on your dates.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 → Denver

showing indicative fares · loading live prices…
Frontier
Frontier CHEAPEST
STL → DEN · Economy
lowest fare seen on this route
$48.97
$29.38
Select
Southwest
Southwest
STL → DEN · Economy
lowest fare seen on this route
$113.23
$67.94
Select
American Airlines
American Airlines
STL → DEN · Economy
lowest fare seen on this route
$125.17
$75.10
Select
United Airlines
United Airlines
STL → DEN · Economy
lowest fare seen on this route
$135.88
$81.53
Select
Delta Air Lines
Delta Air Lines
STL → DEN · Economy
lowest fare seen on this route
$185.81
$111.49
Select
Alaska Airlines
Alaska Airlines
STL → DEN · Economy
lowest fare seen on this route
$702.16
$421.30
Select
See all flights & times → Prices per adult, one way, incl. taxes & fees. Availability changes constantly.
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Cheapest fares from St Louis to Denver

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

AirlineCabin Found fareOur discounted fare Fare found on
Frontier Frontier Economy $48.97 $29.38 Sep 19, 2026 Book
Southwest Southwest Economy $113.23 $67.94 Sep 19, 2026 Book
American Airlines American Airlines Economy $125.17 $75.10 Sep 19, 2026 Book
United Airlines United Airlines Economy $135.88 $81.53 Sep 19, 2026 Book
Delta Air Lines Delta Air Lines Economy $185.81 $111.49 Sep 19, 2026 Book
Alaska Airlines Alaska Airlines Economy $702.16 $421.30 Sep 19, 2026 Book
Air Canada Air Canada Economy $718.11 $430.87 Sep 19, 2026 Book

Discounted fares are negotiated phone deals from our vendor network and may not appear in online search results — call 1-856-513-6369 to lock one in. Fares were found on the dates shown, are per person in USD, and change with availability.

Related routes

↩ Denver to St Louis St Louis to Albuquerque St Louis to Cincinnati / Covington St Louis to Dallas St Louis to Dallas-Fort Worth St Louis to Detroit St Louis to El Paso Albany to Denver Anchorage to Denver Atlanta to Denver Austin to Denver Buffalo to Denver Burbank to Denver All routes →

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Page updated September 20, 2026 · fare data refreshed automatically from live flight searches.