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$29+ Cheap flights from St. Louis to Denver (STL - DEN)

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 1/10. Fares are subject to change and may not be available on all flights or dates of travel.
STL — DEN
Jan 9 — Jan 161
Fri 1/9
Fri 1/16
1 adult, Economy
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Find cheap flights from St. Louis to Denver with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.

Cheapflights Tip: The best prices from Lambert-St Louis to Denver Intl are usually found in October or February, booked 75 days in advance, depart on a Wednesday or Friday and return on a Friday

Cheap flight deals from St. Louis to Denver

Cheapest flights from St. Louis to Denver
Explore the most affordable flight options available from St. Louis to Denver. Find the lowest fares from popular airlines and budget airlines, with prices last updated on December 10, 2025.

This Cheapflightsfares deal was found by Cheapflights users on 12/7. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/317:43 pmSTL - DEN
Nonstop2h 32mFrontier
Mon 1/56:50 amDEN - STL
Nonstop2h 12mFrontier
Deal found 12/7$160
This Frontier deal was found by Cheapflights users on 12/9. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/177:43 pmSTL - DEN
Nonstop2h 32mFrontier
Wed 12/316:50 amDEN - STL
Nonstop2h 12mFrontier
Deal found 12/9$169
This Frontier deal was found by Cheapflights users on 12/8. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/2210:10 pmSTL - DEN
1 stop6h 48mFrontier
Sat 12/276:50 amDEN - STL
Nonstop2h 12mFrontier
Deal found 12/8$171
This Expedia deal was found by Cheapflights users on 12/8. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/177:43 pmSTL - DEN
Nonstop2h 32mFrontier
Fri 12/196:15 amDEN - STL
1 stop12h 32mFrontier
Deal found 12/8$176
This CheapOair deal was found by Cheapflights users on 12/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/317:43 pmSTL - DEN
Nonstop2h 32mFrontier
Tue 1/611:59 pmDEN - STL
1 stop21h 34mFrontier
Deal found 12/10$178
This Super.com deal was found by Cheapflights users on 12/9. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/177:43 pmSTL - DEN
Nonstop2h 32mFrontier
Sat 12/206:50 amDEN - STL
Nonstop2h 12mFrontier
Deal found 12/9$181
This Super.com deal was found by Cheapflights users on 12/7. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/2010:10 pmSTL - DEN
1 stop6h 48mFrontier
Sat 12/276:50 amDEN - STL
Nonstop2h 12mFrontier
Deal found 12/7$191
This Kiwi.com deal was found by Cheapflights users on 12/8. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/151:16 pmSTL - DEN
1 stop15h 42mFrontier
Tue 12/168:00 amDEN - STL
2 stops13h 33mFrontier
Deal found 12/8$193

Find flight deals from St. Louis to Denver

Discover tips and strategies to find the most affordable flight options for your journey from St. Louis (STL) to Denver (DEN). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated December 10, 2025.

Most accurate provider

CheapOair
3 stars

Most trusted provider

CheapOair
3 stars

Round-trip from

$73
(Frontier)

One-way from

$29
(Expedia)

Popular in

March

Cheapest in

October

Average price

$229

Good round-trip deal

$218 or less

Good one-way deal

$128 or less
Provider with most accurate pricing for Lambert-St Louis-Denver Intl flight deals.
Search Deals
Provider most trusted by Cheapflights users for Lambert-St Louis-Denver Intl flights.
Search Deals
From Lambert-St Louis to Denver Intl
Search Deals
One-way flight from Lambert-St Louis to Denver Intl
Search Deals
Highest demand for flights based on searches. 7% potential increase in price ($19 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 4% potential price decrease ($10 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
Search Deals
Price to beat on a round-trip flight from Lambert-St Louis to Denver Intl.
Search Deals
Price to beat on a one-way flight from Lambert-St Louis to Denver Intl.
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from St. Louis to Denver that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated December 10, 2025.
Use the filters below to find and compare flights from St. Louis to Denver that are best for you.

Fly from

St. Louis

Fly to

Denver

Route

Depart

Return

Price

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Sat 1/17

7:00 am-11:54 am

1 stop5h 54m

Denver Intl

Sat 1/17

5:51 pm-11:25 pm

1 stop4h 34m

$177

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 1/14

6:05 am-11:50 am

1 stop6h 45m

Denver Intl

Wed 1/21

6:40 pm-9:45 pm

Nonstop2h 05m

$207

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 2/18

6:35 am-1:35 pm

1 stop8h 00m

Denver Intl

Tue 2/24

7:05 am-2:47 pm

1 stop6h 42m

$237

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Thu 1/8

8:45 am-10:21 am

Nonstop2h 36m

Denver Intl

Sat 1/10

5:50 pm-8:58 pm

Nonstop2h 08m

$250

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 1/7

6:00 pm-7:38 pm

Nonstop2h 38m

Denver Intl

Sun 1/11

1:53 pm-4:55 pm

Nonstop2h 02m

$262

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Fri 1/30

6:00 pm-7:38 pm

Nonstop2h 38m

Denver Intl

Sun 2/1

10:10 am-1:16 pm

Nonstop2h 06m

$262

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Fri 1/23

8:45 am-10:21 am

Nonstop2h 36m

Denver Intl

Sun 1/25

5:50 pm-8:58 pm

Nonstop2h 08m

$262

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Thu 1/1

10:35 am-3:40 pm

2 stops6h 05m

Denver Intl

Wed 1/7

6:40 pm-9:45 pm

Nonstop2h 05m

$267

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Mon 1/12

6:20 am-7:50 am

Nonstop2h 30m

Denver Intl

Thu 1/15

6:35 pm-9:40 pm

Nonstop2h 05m

$270

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 1/21

10:15 am-3:30 pm

2 stops6h 15m

Denver Intl

Sat 1/24

9:45 am-5:00 pm

1 stop6h 15m

$282

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/8

Showing 1-10 of 20 results
1
2

Compare providers for flights from St. Louis to Denver

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from St. Louis to Denver in December.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy2 starsTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*1 star
eDreamsPrice Accuracy3 starsTrust Score*3 stars
CheapflightsfaresPrice Accuracy3 starsTrust Score*2 stars
JustAirTicketPrice Accuracy-Trust Score*1 star
CheapOairPrice Accuracy3 starsTrust Score*3 stars
CheapTicketsDealPrice Accuracy3 starsTrust Score*3 stars
CheapfaremartPrice Accuracy-Trust Score*1 star

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on St. Louis-Denver flights, users find the pricing of CheapOair to be most consistent on Cheapflights vs. CheapOair Users can find the same prices on St. Louis-Denver flight deals on Cheapflights vs. CheapOair >95% of the time. Price accuracy is based on data collected from St. Louis-Denver flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on St. Louis-Denver flights, Cheapflights users trust CheapOair the most. CheapOair has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for St. Louis-Denver flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

Best time to book a flight from St. Louis to Denver

Have a flexible travel schedule? Discover the best time to fly to Denver from St. Louis with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from St. Louis to Denver

How far ahead should I book a flight from St. Louis to Denver?

Use this chart to determine the optimal time to book a round-trip flight from St. Louis to Denver. Price data was last updated on December 5, 2025.

Booking 75 days in advance of your planned departure date is, on average, the best time to get cheap flights from St. Louis to Denver. The general trend is that the closer you book to the departure date, the more expensive your flight will be.

What is the cheapest month to book a flight from St. Louis to Denver?

Currently, February is the cheapest month in which you can book a flight from St. Louis to Denver (average of $36). Flying from St. Louis to Denver in July is currently the most expensive (average of $104). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from STL to DEN?

Find hourly flight availability from St. Louis to Denver. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated December 10, 2025.

It’s optimal to fly from St. Louis to Denver in the evening. By choosing this option you can save up to 62% on the cost of your flight, compared to a flight at noon.

What is the cheapest day to fly from St. Louis to Denver?

Use this chart to determine the cheapest time to fly round-trip from St. Louis to Denver. Price data was last updated on December 6, 2025.

Travelers seeking maximum savings on their St. Louis to Denver flight should consider departing on Saturday evenings when fares are most often at their lowest. Monday at noon flights should be avoided if possible as fares are typically the most expensive at this time.

The best insider tips for St. Louis to Denver flights

AI-powered summary based on content written by travel experts. AI can make mistakes.
Cheapflights partnered with top experts to bring you the best recommendations for your St. Louis to Denver trip
Airlines
Frontier

Frontier's UpFront Plus guarantees an empty middle seat for extra comfort.


Early check-in helps secure your place due to frequent overbooking.

Read more about FrontierBy Marisa Garcia
United Airlines

Basic Economy allows a personal item only; no carry-on bags without extra fees.


Economy Plus offers extra legroom seats at the front of the economy cabin.

Read more about United AirlinesBy Harriet Baskas
Airports
STL

Security at STL is generally quick, taking 5 to 10 minutes during off-peak times. Check real-time wait times online before heading to the airport.

Read more about STLBy Taryn White
DEN

Take the A Line train from DEN to Union Station in 37 minutes. It runs every 15 minutes and is a cost-effective way to reach downtown Denver.

Read more about DENBy Emily Zemler
Our travel experts
Marisa Garcia

Marisa Garcia

Expert on Frontier

Marisa Garcia

Marisa Garcia

Marisa knows planes inside and out, spending 16 years working on aircraft in hangars at airports around the world. She is an aviation industry expert, specialized in airline interiors and regulations. Ten years ago, she pivoted to journalism. She shares her insights in leading aviation, travel, and business publications and on her site FlightChic.

Read more
Harriet Baskas

Harriet Baskas

Expert on United Airlines

Harriet Baskas

Harriet Baskas

Harriet is an award-winning journalist who is happiest in an airport or an unusual museum. Her stories about airports, air travel, and the business of travel have appeared on NBC News, CNBC, USA TODAY, The Points Guy and other outlets. She is the creator of the StuckatTheAirport.com blog and the author of nine books. When not out on the road or exploring the latest airport amenities, she’s home in Seattle getting ready for the next adventure.

Read more
Taryn White

Taryn White

Expert on STL

Taryn White

Taryn White

Taryn White is a freelance travel writer, digital creator, and travel advisor who has visited nearly 100 countries and all 50 states. She’s familiar with many airports and enjoys beach hopping, boutique hotels, spa experiences, and exploring local culture. Her work has appeared in Travel + Leisure, Condé Nast Traveler, National Geographic, Smithsonian Magazine, AFAR, and more.

Read more
Emily Zemler

Emily Zemler

Expert on DEN

Emily Zemler

Emily Zemler

Emily is a freelance writer and book author based in London covering entertainment and travel. Her work has appeared in Los Angeles Times, Observer, and Conde Nast Traveler She has ventured to more than 40 countries and all seven continents, always in search of a great art museum. She has written extensively about hotels, luxury travel, and aviation.

Read more

Reviews of airlines servicing Denver

Get insights into the airlines that provide service to Denver. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Denver. Reviews last updated December 10, 2025.
Get a feel of what it's like to fly with Southwest, Delta, and United Airlines from St. Louis to Denver by reading reviews from past customers. Users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
7.9
Good
4,253 reviews

Comfort

8.0

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Crew

8.6

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Southwest
7.9
Good
4,253 reviews
Southwest
7.9
Good
4,253 reviews

Comfort

8.0

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Crew

8.6

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Delta
7.9
Good
8,007 reviews
Southwest
7.9
Good
4,253 reviews

Comfort

8.0

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Crew

8.6

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
United Airlines
7.4
Good
9,092 reviews
Southwest
7.9
Good
4,253 reviews

Comfort

8.0

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Crew

8.6

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
American Airlines
7.2
Good
11,048 reviews
Southwest
7.9
Good
4,253 reviews

Comfort

8.0

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Crew

8.6

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Frontier
5.8
Fair
3,085 reviews
Southwest
7.9
Good
4,253 reviews

Comfort

8.0

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Crew

8.6

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

Related info for your journey

Find useful and relevant information for your journey from St. Louis to Denver. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airports do I use to fly from St. Louis to Denver?

    You will need to book a flight from Lambert-St Louis to Denver Intl if you want to fly from St. Louis to Denver. At least 5 different airlines have flights from Lambert-St Louis (STL) to Denver Intl (DEN) on a regular basis. There are 9 flights to Denver from the St. Louis airport per day. If you manage to book one that is nonstop, then you can expect the flight time from STL to DEN to be around 2h 20m.

  • How popular is this St. Louis to Denver flight route?

    Flights from Lambert-St Louis to Denver Intl have been viewed 179 times in the past calendar month.

  • How long is the flight from St. Louis to Denver?

    Departing from St. Louis to Denver will take you 2h 36m. Airlines will cover a distance of 767 mi. Both multi-stop and nonstop flights can be found to your destination and back.

  • What are the cheapest airlines flying from St. Louis to Denver round-trip?

    Frontier, at $46, was found to be the cheapest airline from St. Louis to Denver.Alternate airlines to your destination round-trip include Delta and United Airlines. Users have found that Frontier is 79% cheaper than the other options available to this destination.

  • What are the cheapest airlines to fly from St. Louis to Denver one-way?

    One-way options have recently been found by users for as low as $29 on Frontier. Other airlines that offer cheap prices include Southwest from $78 and United Airlines from $89 one-way.

  • What are the most reliable airlines from St. Louis to Denver?

    No one likes to see their flight delayed. When booking a flight from St. Louis to Denver consider choosing SkyWest Airlines (100%), Frontier (90%) or Air Canada (84%) as they are the most reliable in getting you off to your destination on time.

  • What are the cheapest flights from St. Louis to Denver?

    Looking for the cheapest flight from St. Louis to Denver? While on average our users pay $1,054, our data indicates the cheapest price to be $65. The most popular route (Lambert-St Louis - Denver Intl), is priced around $109.

  • Can I find deals for flights from St. Louis to Denver that include hotel bookings?

    Yes. In addition to deals on St. Louis to Denver flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from St. Louis to Denver?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from St. Louis to Denver.

  • Can I find deals for business class flights from St. Louis to Denver?

    Yes. Cheapflights offers flight deals from St. Louis to Denver by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from St. Louis to Denver?

    Currently, February is the cheapest month in which you can book a flight from St. Louis to Denver (average of $36). Flying from St. Louis to Denver in July is currently the most expensive (average of $104). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Traveling to a place near Denver?

Book flights to Denver if you plan to visit one of these locations
Black Hawk
Thornton
Westminster
Broomfield
Lakewood
Golden
Winter Park
Greeley
Lone Tree
Cripple Creek
Silverthorne
Central City
Frisco
Wheat Ridge
Manitou Springs
Fort Morgan
Brighton
Longmont
Idaho Springs
Parker

Browse thousands of different options on Cheapflights for your next trip

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Alternative routes for St. Louis to Denver

See prices for flight routes from nearby airports that may be better suited for you.
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Top 5 airlines flying from St. Louis to Denver

Discover the top 5 airlines that operate flights from St. Louis to Denver. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated December 10, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$50Average$125FlexibilityNo cancel feeOn-time62%
DeltaCheapest$128Average$326FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$158Average$316FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$176Average$297FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$201Average$259FlexibilityNo cancel feeOn-time71%

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