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$84+ 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 8/14. Fares are subject to change and may not be available on all flights or dates of travel.
STL — DEN
Jul 7 — Jul 141
Mon 7/7
Mon 7/14
1 adult, Economy
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Cheapflights Tip: The best prices from Lambert-St Louis to Denver Intl are usually found in September or August, booked 23 days in advance, depart on a Wednesday or Friday and return on a Wednesday

Cheap 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 July 2, 2025.

Round-trip from

$122
(Frontier)

One-way from

$84
(Southwest)

Popular in

March

Cheapest in

September

Average price

$214

Good round-trip deal

$257 or less

Good one-way deal

$132 or less
From Lambert-St Louis to Denver Intl
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One-way flight from Lambert-St Louis to Denver Intl
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Highest demand for flights based on searches. 15% potential increase in price ($40 potential increase over avg. RT price).
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Cheapest flight prices on average. 5% potential price decrease ($11 potential savings vs. average RT price).
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Average for round-trip flights in July 2025
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Price to beat on a round-trip flight from Lambert-St Louis to Denver Intl.
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Price to beat on a one-way flight from Lambert-St Louis to Denver Intl.
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Find 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 July 2, 2025.

This Frontier deal was found by Cheapflights users on 7/1. 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.
Fri 7/117:29 pmSTL - DEN
Nonstop2h 29mFrontier
Mon 7/146:00 amDEN - STL
Nonstop2h 11mFrontier
Deal found 7/1$122
This Southwest deal was found by Cheapflights users on 7/2. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/165:45 amSTL - DEN
Nonstop2h 15mSouthwest
Mon 8/187:45 amDEN - STL
Nonstop2h 05mSouthwest
Deal found 7/2$157

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 July 2, 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

Fri 8/1

7:29 pm-8:58 pm

Nonstop2h 29m

Denver Intl

Fri 8/8

6:00 am-9:11 am

Nonstop2h 11m

$123

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Sat 8/16

5:45 am-7:00 am

Nonstop2h 15m

Denver Intl

Mon 8/18

7:45 am-10:50 am

Nonstop2h 05m

$157

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Mon 8/25

7:23 am-1:25 pm

1 stop7h 02m

Denver Intl

Wed 8/27

9:41 am-3:49 pm

1 stop5h 08m

$177

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Thu 8/14

9:50 am-12:15 pm

1 stop3h 25m

$84

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Thu 10/9

9:47 am-8:27 pm

1 stop11h 40m

$85

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Sat 11/1

7:01 am-11:46 am

1 stop5h 45m

$93

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Thu 11/27

8:30 am-2:58 pm

1 stop7h 28m

$99

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Sat 7/12

8:40 am-8:56 pm

1 stop13h 16m

$113

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Mon 11/24

4:43 pm-6:14 pm

Nonstop2h 31m

$115

Flights are sorted by cheapest round-trip flights first.

Deals found on 6/30

The best insider tips for St. Louis to Denver flights

Snippets provided in this section are AI-generated based on a summarization of Cheapflights-commissioned articles. The articles are presented as-is, for general informational purposes only, and may not be up-to-date. The opinions contained in the articles are original to the author and reflect their authentic experience, which may vary significantly from the experience of others.
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

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 June 27, 2025.

Booking 23 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, October is the cheapest month in which you can book a flight from St. Louis to Denver (average of $197). Flying from St. Louis to Denver in March is currently the most expensive (average of $278). 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 July 2, 2025.

It’s optimal to fly from St. Louis to Denver in the evening. By choosing this option you can save up to 66% on the cost of your flight, compared to a flight in the morning.

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 June 29, 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 mornings flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from St. Louis to Denver

Explore weekly flight availability from St. Louis to Denver. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated July 2, 2025.

The most flights from STL to DEN are scheduled on a Monday (19 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (6 on average).

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 July 2, 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
8.0
Very good
4,272 reviews

Overall

8.0

Entertainment

7.6

Comfort

8.0

Food

7.0

Boarding

8.2

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Gina,Apr 2025

LAS - DEN

Good, the crew was friendly and helpful. The pilot had great skills in keeping the plane stable through rough turbulence. Smooth landing, too! Thank you!
Southwest
8.0
Very good
4,272 reviews
Southwest
8.0
Very good
4,272 reviews

Overall

8.0

Entertainment

7.6

Comfort

8.0

Food

7.0

Boarding

8.2

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Gina,Apr 2025

LAS - DEN

Good, the crew was friendly and helpful. The pilot had great skills in keeping the plane stable through rough turbulence. Smooth landing, too! Thank you!
Delta
8.0
Very good
7,983 reviews
Southwest
8.0
Very good
4,272 reviews

Overall

8.0

Entertainment

7.6

Comfort

8.0

Food

7.0

Boarding

8.2

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Gina,Apr 2025

LAS - DEN

Good, the crew was friendly and helpful. The pilot had great skills in keeping the plane stable through rough turbulence. Smooth landing, too! Thank you!
United Airlines
7.4
Good
8,861 reviews
Southwest
8.0
Very good
4,272 reviews

Overall

8.0

Entertainment

7.6

Comfort

8.0

Food

7.0

Boarding

8.2

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Gina,Apr 2025

LAS - DEN

Good, the crew was friendly and helpful. The pilot had great skills in keeping the plane stable through rough turbulence. Smooth landing, too! Thank you!
American Airlines
7.2
Good
10,000 reviews
Southwest
8.0
Very good
4,272 reviews

Overall

8.0

Entertainment

7.6

Comfort

8.0

Food

7.0

Boarding

8.2

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Gina,Apr 2025

LAS - DEN

Good, the crew was friendly and helpful. The pilot had great skills in keeping the plane stable through rough turbulence. Smooth landing, too! Thank you!
Sun Country Air
6.9
Okay
340 reviews
Southwest
8.0
Very good
4,272 reviews

Overall

8.0

Entertainment

7.6

Comfort

8.0

Food

7.0

Boarding

8.2

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Gina,Apr 2025

LAS - DEN

Good, the crew was friendly and helpful. The pilot had great skills in keeping the plane stable through rough turbulence. Smooth landing, too! Thank you!

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 12 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 15m.

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

    Flights from Lambert-St Louis to Denver Intl have been viewed 191 times in the past calendar month.

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

    Frontier, at $122, was found to be the cheapest airline from St. Louis to Denver.Alternate airlines to your destination round-trip include Southwest and American Airlines. Users have found that Frontier is 42% 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 $84 on Southwest. Other airlines that offer cheap prices include Frontier from $85 and American Airlines from $93 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 (96%), United Airlines (74%) or Air Canada (71%) 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 $1,152, our data indicates the cheapest price to be $79. The most popular route (Lambert-St Louis - Denver Intl), is priced around $144.

  • 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, October is the cheapest month in which you can book a flight from St. Louis to Denver (average of $197). Flying from St. Louis to Denver in March is currently the most expensive (average of $278). 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 St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
Westminster
Black Hawk
Winter Park
Lakewood
Cripple Creek
Golden
Brighton
Silverthorne
Thornton
Frisco
Broomfield
Grand Lake
Manitou Springs
Central City
Fort Morgan
Glendale
Copper Mountain
Wheat Ridge
Longmont
Idaho Springs

Browse thousands of different options on Cheapflights for your next trip

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Alternative routes for St. Louis to Denver

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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 July 2, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$45Average$120FlexibilityNo cancel feeOn-time62%
DeltaCheapest$128Average$266FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$153Average$310FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$180Average$297FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$201Average$236FlexibilityNo cancel feeOn-time71%

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