HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Denver

$83+ 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 7/9. Fares are subject to change and may not be available on all flights or dates of travel.
STL — DEN
Jun 17 — Jun 241
Tue 6/17
Tue 6/24
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

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 September or August, booked 23 days in advance, depart on a Wednesday or Friday and return on a Saturday

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 June 12, 2025.

Round-trip from

$139
(Priceline)

One-way from

$84
(Frontier)

Popular in

March

Cheapest in

September

Average price

$261

Good round-trip deal

$244 or less

Good one-way deal

$123 or less
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. 16% potential increase in price ($40 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 5% potential price decrease ($12 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in June 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

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 June 12, 2025.

This Priceline deal was found by Cheapflights users on 6/12. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/97:29 pmSTL - DEN
Nonstop2h 29mFrontier
Wed 7/166:00 amDEN - STL
Nonstop2h 11mFrontier
Deal found 6/12$139
This Southwest deal was found by Cheapflights users on 6/10. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/46:45 pmSTL - DEN
Nonstop2h 20mSouthwest
Thu 8/145:30 amDEN - STL
Nonstop2h 00mSouthwest
Deal found 6/10$157
This American Airlines deal was found by Cheapflights users on 6/10. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/1212:20 pmSTL - DEN
1 stop6h 43mAmerican Airlines
Sat 8/1611:59 pmDEN - STL
1 stop7h 07mAmerican Airlines
Deal found 6/10$182
This United Airlines deal was found by Cheapflights users on 6/10. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/128:00 amSTL - DEN
1 stop5h 32mUnited Airlines
Sat 8/161:25 pmDEN - STL
Nonstop2h 06mUnited Airlines
Deal found 6/10$187
This Delta deal was found by Cheapflights users on 6/10. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/237:45 amSTL - DEN
1 stop8h 15mDelta
Fri 7/2512:59 amDEN - STL
1 stop7h 02mDelta
Deal found 6/10$197

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 June 12, 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

Wed 7/9

7:29 pm-8:58 pm

Nonstop2h 29m

Denver Intl

Wed 7/16

6:00 am-9:11 am

Nonstop2h 11m

$139

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Mon 8/4

6:45 pm-8:05 pm

Nonstop2h 20m

Denver Intl

Thu 8/14

5:30 am-8:30 am

Nonstop2h 00m

$157

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Tue 8/12

12:20 pm-6:03 pm

1 stop6h 43m

Denver Intl

Sat 8/16

11:59 pm-8:06 am

1 stop7h 07m

$182

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Tue 8/12

5:31 pm-11:22 pm

1 stop6h 51m

Denver Intl

Sat 8/16

5:37 pm-8:45 pm

Nonstop2h 08m

$187

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 7/23

7:45 am-3:00 pm

1 stop8h 15m

Denver Intl

Fri 7/25

12:59 am-9:01 am

1 stop7h 02m

$197

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Sun 6/29

6:12 am-8:39 am

1 stop27h 27m

Denver Intl

Thu 7/3

6:13 pm-11:30 am

1 stop16h 17m

$325

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 7/9

7:29 pm-8:58 pm

Nonstop2h 29m

$83

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Sat 7/26

5:15 am-6:52 am

Nonstop2h 37m

$89

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 7/23

7:45 am-3:00 pm

1 stop8h 15m

$99

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Sat 7/12

7:40 am-8:56 pm

1 stop14h 16m

$118

Flights are sorted by cheapest round-trip flights first.

Deals found on 6/12

Showing 1-10 of 14 results
1
2

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 9, 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 June 12, 2025.

It’s optimal to fly from St. Louis to Denver in the evening. By choosing this option you can save up to 67% 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 8, 2025.

Travelers seeking maximum savings on their St. Louis to Denver flight should consider departing on Tuesday 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 June 12, 2025.

The most flights from STL to DEN are scheduled on a Monday (18 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (6 on average).

Rainfall in Denver by month

Plan your trip to Denver by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Denver ranges from 0.5 - 2.3 inches per month. May is typically the wettest month, when rainfall can reach 2.3 in. January is typically the driest time to visit Denver when rainfall is around 0.5 in.

Temperature in Denver by month

Plan your trip to Denver by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Denver, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 73.4 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 30.2 F).

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 June 12, 2025.
Read through reviews of airlines operating flights from St. Louis to Denver, such as Alaska Airlines, Southwest and Delta. In addition to providing an overall rating, users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Food

7.1

Crew

8.5

Comfort

7.8

Overall

8.0

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Alaska Airlines
8.0
Very good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Food

7.1

Crew

8.5

Comfort

7.8

Overall

8.0

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Southwest
8.0
Very good
4,287 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Food

7.1

Crew

8.5

Comfort

7.8

Overall

8.0

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Delta
8.0
Very good
7,950 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Food

7.1

Crew

8.5

Comfort

7.8

Overall

8.0

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
United Airlines
7.4
Good
8,790 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Food

7.1

Crew

8.5

Comfort

7.8

Overall

8.0

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
American Airlines
7.2
Good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Boarding

8.1

Food

7.1

Crew

8.5

Comfort

7.8

Overall

8.0

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.

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 13 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 192 times in the past calendar month.

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

    Frontier, at $139, 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 34% 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 Frontier. Other airlines that offer cheap prices include United Airlines from $89 and Delta from $99 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 (95%), United Airlines (79%) or Air Canada (74%) 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 $865, our data indicates the cheapest price to be $76. The most popular route (Lambert-St Louis - Denver Intl), is priced around $146.

  • 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
Grand Lake
Broomfield
Central City
Glendale
Copper Mountain
Wheat Ridge
Longmont
Idaho Springs
Greeley
Limon

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for St. Louis to Denver

See prices for flight routes from nearby airports that may be better suited for you.
Kansas City to Denver flights
Springfield to Denver flights
St. Louis to Colorado Springs flights
Kansas City to Grand Junction flights
Kansas City to Colorado Springs flights
Springfield to Colorado Springs flights
St. Louis to Montrose flights
St. Louis to Durango flights
Columbia to Denver flights
Joplin to Denver flights
St. Louis to Grand Junction flights
Kansas City to Durango flights
Kansas City to Hayden flights
St. Louis to Vail flights
St. Louis to Aspen flights
St. Louis to Gunnison flights
Kansas City to Aspen flights
St. Louis to Hayden flights
Cape Girardeau to Denver flights
Branson to Denver flights
Kansas City to Cortez flights
Columbia to Colorado Springs flights
Springfield to Hayden flights
St. Louis to Cortez flights
Kansas City to Alamosa flights
Joplin to Colorado Springs flights
Columbia to Aspen flights

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 June 12, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$45Average$117FlexibilityNo cancel feeOn-time62%
DeltaCheapest$128Average$256FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$152Average$309FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$187Average$298FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$192Average$242FlexibilityNo cancel feeOn-time71%

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.