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$40 Cheap Flights from Denver (DEN) to St. Louis (STL)

View $40 flight on Sat, Sep 26, 2026Opens in a new window

Popular airlines from Denver Intl. Airport (DEN) to St. Louis Lambert Intl. Airport (STL)

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Cheap Flights from Denver to St. Louis (DEN-STL)

Prices were available within the past 7 days and start at $40 for one-way flights and $80 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Frontier Airlines
Sat, Sep 26 - Sat, Oct 3
DEN
Denver
STL
St. Louis
$80 Roundtrip, just found
$80
Roundtrip
just found
Select Frontier Airlines flight, departing Sat, Sep 26 from Denver to St. Louis, returning Sat, Oct 3, priced at $80 just found
Frontier Airlines
Wed, Oct 21 - Sat, Oct 24
DEN
Denver
STL
St. Louis
$86 Roundtrip, just found
$86
Roundtrip
just found
Select Frontier Airlines flight, departing Wed, Oct 21 from Denver to St. Louis, returning Sat, Oct 24, priced at $86 just found
Frontier Airlines
Sat, Sep 19 - Wed, Sep 23
DEN
Denver
STL
St. Louis
$88 Roundtrip, just found
$88
Roundtrip
just found
Select Frontier Airlines flight, departing Sat, Sep 19 from Denver to St. Louis, returning Wed, Sep 23, priced at $88 just found
Frontier Airlines
Wed, Sep 9 - Fri, Sep 11
DEN
Denver
STL
St. Louis
$101 Roundtrip, just found
$101
Roundtrip
just found
Select Frontier Airlines flight, departing Wed, Sep 9 from Denver to St. Louis, returning Fri, Sep 11, priced at $101 just found
Frontier Airlines
Sat, Oct 10 - Sat, Oct 17
DEN
Denver
STL
St. Louis
$103 Roundtrip, found 3 hours ago
$103
Roundtrip
found 3 hours ago
Select Frontier Airlines flight, departing Sat, Oct 10 from Denver to St. Louis, returning Sat, Oct 17, priced at $103 found 3 hours ago
Frontier Airlines
Thu, Nov 5 - Fri, Nov 13
DEN
Denver
STL
St. Louis
$106 Roundtrip, found 1 hour ago
$106
Roundtrip
found 1 hour ago
Select Frontier Airlines flight, departing Thu, Nov 5 from Denver to St. Louis, returning Fri, Nov 13, priced at $106 found 1 hour ago
Southwest Airlines
Thu, Sep 10 - Mon, Sep 14
DEN
Denver
STL
St. Louis
$133 Roundtrip, just found
$133
Roundtrip
just found
Select Southwest Airlines flight, departing Thu, Sep 10 from Denver to St. Louis, returning Mon, Sep 14, priced at $133 just found
American Airlines
Wed, Oct 21 - Sat, Oct 24
DEN
Denver
STL
St. Louis
$142 Roundtrip, just found
$142
Roundtrip
just found
Select American Airlines flight, departing Wed, Oct 21 from Denver to St. Louis, returning Sat, Oct 24, priced at $142 just found
United
Thu, Sep 10 - Mon, Sep 14
DEN
Denver
STL
St. Louis
$177 Roundtrip, just found
$177
Roundtrip
just found
Select United flight, departing Thu, Sep 10 from Denver to St. Louis, returning Mon, Sep 14, priced at $177 just found
Delta
Thu, Sep 10 - Mon, Sep 14
DEN
Denver
STL
St. Louis
$197 Roundtrip, just found
$197
Roundtrip
just found
Select Delta flight, departing Thu, Sep 10 from Denver to St. Louis, returning Mon, Sep 14, priced at $197 just found

Alternative airports near St. Louis

Prices were available within the past 7 days. Prices and availability are subject to change.

Select flight to Lambert-St. Louis Intl. STL. Cheapest option available. Average driving time to city center is 20 minutes. Flights from $292
STL
Lambert-St. Louis Intl.
Cheapest
Average driving time to city center20 min
Flights from $292

What you need to know for your flight from Denver Intl. to Lambert-St. Louis Intl.

Denver (DEN) to St. Louis (STL) at a glance

Travel from Denver (DEN) to St. Louis (STL) with a range of airlines on this domestic short-haul route. Discover various options, from budget-friendly fares to full-service carriers, that cater to your travel needs and financial plans. As you prepare to explore the vibrant sights and neighborhoods of St. Louis, you can find key details for flights departing from Denver International Airport (DEN) to Lambert-St. Louis International Airport (STL), including daily fares and the cheapest flights from Denver.

  • Fastest flight duration: around 2 hours non-stop
  • Route distance: roughly 800 miles (1,290 km)
  • Flights per week: around 30+ flights with multiple daily departures on average
  • Typical fares (one-way): economy tickets often range from $45–$415, depending on seasonality and how far ahead you book

Flights from Denver International Airport (DEN) to Lambert-St. Louis International Airport (STL)

Based on recent traveler bookings, here are the top airlines favored for flights from Denver to St. Louis, focusing on both non-stop and one-stop options. Many travelers choose routes that include popular layovers at O'Hare International Airport (ORD, approximately 1 hour 15 minutes), Dallas-Fort Worth International Airport (DFW, around 1 hour 15 minutes), and Harry Reid International Airport (LAS, about 2 hours). This variety allows you to balance price, total travel time, and cabin class to create the best itinerary for your needs.

  • Southwest Airlines: This budget-friendly airline provides both non-stop and one-stop options, with one-way ticket prices generally between $80 and $435. It represents about 46% of departures on this route, offering a typical non-stop flight duration of 2 hours.
  • United: As a full-service airline, United offers both non-stop and one-stop services, with one-way fares usually falling between $90 and $415. It accounts for approximately 37% of departures on this route and has a standard non-stop travel time of 2 hours.
  • Frontier Airlines: A low-cost option, Frontier provides non-stop and one-stop services, with one-way fares typically ranging from $45 to $225. It comprises around 15% of departures on this route, with non-stop flights taking about 2 hours.
  • American Airlines: This full-service carrier offers one-stop flights, with one-way fares typically between $95 and $275. It makes up about 2% of departures on this route, featuring an in-flight duration of 4 hours and an overall journey time of approximately 5 hours and 30 minutes, including layover.
  • Delta: Delta is a full-service airline providing one-stop service, with one-way fares generally ranging from $100 to $435. It represents roughly 1% of departures on this route, with an in-flight time of 4 hours and a total travel duration of about 5 hours and 30 minutes, including layover.

Travelers can opt for an upgrade on their flight from Denver to St. Louis, as United Airlines provides first-class service on this route.

Best time to fly from Denver (DEN) to St. Louis (STL)

The most popular months for travelers flying from Denver to St. Louis are March, April, and October, when peak temperatures in St. Louis reach up to 58.6°F in October. If you prefer quieter travel, consider November, the least busy and relatively cheaper time to visit with fewer crowds and temperatures around 46.2°F. For better deals, September usually offers the lowest average one-way fare around $147. Flight availability peaks in October, with approximately 47 flights per week, making it easier to find convenient departure times. January has the fewest flights, with approximately 20 flights per week.

  • Cheapest time to fly: September usually offers good deals with average one-way fare around $147, roughly 13% cheaper than the yearly average.
  • Another budget-friendly time to fly: October typically offers an average one-way fare of around $156.
  • Most flight options: October has the highest number of flights from Denver to St. Louis, with approximately 47 flights per week, giving you more flexibility in scheduling your trip.
calendar iconMonthtemperature iconTemperaturecrowd level iconDemandflights iconWeekly Flightsprice iconAverage one-way Fare
January31.6°F (-0.2°C)Slightly Low20$170
February34.9°F (1.6°C)Average24$162
March46.4°F (8.0°C)Slightly High30$193
April56.1°F (13.4°C)Slightly High34$170
May66.6°F (19.2°C)Average39$166
June76.1°F (24.5°C)Average43$184
July78.6°F (25.9°C)Average44$174
August77.0°F (25.0°C)Average42$163
September70.9°F (21.6°C)Average44$147
October58.6°F (14.8°C)Slightly High47$156
November46.2°F (7.9°C)Slightly Low39$165
December37.8°F (3.2°C)Slightly Low34$179

*Average one-way fare is based on Expedia flight booking data from January 2025 to April 2026 for the specified route and travel class and may change depending on availability, dates, and demand.

Alternative route from Denver (DEN) to St. Louis (STL)

  • Colorado Springs to St. Louis (COS-STL): Located approximately 73 miles from Denver International Airport (DEN), Colorado Springs Airport (COS) offers one-way economy fares that generally fall between $110 and $380, influenced by the season and advance booking time. Flights on this route usually feature one-stop options, with popular layover locations being Denver International Airport (DEN) and Dallas-Fort Worth International Airport (DFW). Major airlines servicing this route include United and Southwest Airlines, the latter being a low-cost option. Additionally, first-class service is offered on this route.

How to find the best prices for flights from Denver (DEN) to St. Louis (STL)

Getting some of the best deals on flights from Denver to St. Louis is all about timing and flexibility. Here are some key tips to help you save:

  1. Best times to book and fly: cheaper fares are usually available when booking at least two months in advance, although most travelers tend to book their flights 2 to 8 weeks ahead. Departures in the morning, from 5 AM to 12 PM, often provide lower prices and are the most popular times to fly. Additionally, Saturday flights generally offer cheaper rates, while Friday remains the most popular travel day.
  2. Set up price alerts: stay updated on price changes by using Expedia's Price Tracker. Receive alerts when fares drop for your selected route.
  3. Bundle and save: bundle your flight and hotel to save on Expedia, or unlock a hotel deal after booking your flight.*
  4. Compare flight options: use Expedia's search tool to compare airlines, routes, direct vs. non-direct flights, and flight times. You can also sort by price to find the most affordable options.
  5. Stay flexible with dates: being open to different travel days can sometimes help you find better prices on flights and hotels.
  6. Think about luggage: nowadays, it's important to check the airline's baggage policies to find the best value. That may be paying for an additional carry-on bag or booking a ticket with checked luggage included. Either way, double-check your allowance before confirming your booking to avoid excess baggage fees at the airport.

*Members only. Savings vary and are not available on all bundles. Select hotels.

Arriving at Lambert-St. Louis International Airport from Denver International Airport

St. Louis welcomes travelers from Denver with a range of transport options based on price, convenience, and proximity. Here's how to reach St. Louis efficiently:

  • Hotel transfer: Transfers offer a convenient way to reach your hotel in St. Louis, with private rides that can be arranged in advance.
  • Car rental: Renting a car from Lambert-St. Louis International Airport is a great option if you plan to explore and sightsee beyond the city. Browse cheap car rentals at Lambert-St. Louis International Airport on Expedia.
  • Taxi/ride-hailing: Taxis and ride-hailing services may be available from designated pickup areas outside the terminal, check locally on arrival.
  • Public transportation: From Lambert-St. Louis International Airport, Lambert Main Terminal Station, a metro station, is conveniently located just 0.1 miles away on foot, providing easy access to public transportation.

Frequently asked questions

How much does a flight from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.) cost?
You can find cheap one-way flights from $40 and cheap return flights from $80 Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.) with Expedia. One-way flights typically cost between $150 and $774, and return flights often range between $201 and $946. Flight prices vary based on the month and day of the week you want to travel, as well as the airline and how far in advance you book your ticket. Filter your search on Expedia by "Price (lowest to highest)" to see the cheapest fares first, and use the Price Tracking tool to receive alerts when Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.) ticket fares go up or down.*Typical price ranges based on flights available on Expedia in the last year. Prices include multi-airline options.
What is the cheapest month to fly from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.)?
September is the cheapest month to fly from Denver, CO (DEN) to St. Louis, MO (STL), with average return fares around $275. This fare is about 15% lower than the average price throughout the year, as September typically sees a decrease in travel demand. Other economical months for this route include August and October.*Averages based on flights available on Expedia in the last year.
Which airlines fly direct from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.)?
There are 2 airlines offering direct flights from DEN to STL:

  • United operates around 28 direct flights from DEN to STL every week
  • Frontier Airlines operates around 7 direct flights from DEN to STL every week

What is the cheapest airline that flies from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.)?
Frontier Airlines is one of the cheapest airlines offering nonstop flights from Denver, CO (DEN) to St. Louis, MO (STL), with round-trip tickets starting from around $48. Use Expedia's search tool to compare the prices and schedules of airlines that fly this route to find the best option for your plans and budget.*Prices based on flights available on Expedia in the last year.
How do I find cheap flights from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.)?
To find a cheap flight from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.), be flexible with your dates. Traveling outside of peak vacation months and booking a mid-week flight can help you save. Early morning and late night flights are often more affordable, too. Expedia allows you to compare flight times, airlines and routes all in one place to find low fares. You can also set up Price Tracking and receive alerts when fares go up or down.
What is the best airline to fly with from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.)?
The best airline to fly with from Denver, CO (DEN) to St. Louis, MO (STL) will differ from traveler to traveler. If you like to fly early, WN offers early morning flights. If price is the most important factor, Frontier Airlines typically offers the lowest fares. WN offers the most daily flights from DEN to STL, which is great if flexibility is what you value most. The best carrier for this journey could also be the one you have a loyalty membership with, as flying with that airline or another airline within the same alliance could help you collect points or enjoy lounge access.
What is the best time to fly from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.)?
For flights from Denver (DEN) to St. Louis (STL), September and August are the best months to fly. These months provide the lowest average return flight prices at around $275, making them a great choice for travelers looking to visit St. Louis at a reasonable cost.*Prices based on flights available on Expedia in the last year.
How many flights per day from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.)?
On average, there are around 11 nonstop flights per day from Denver Intl. (DEN) to Lambert-St. Louis Intl. (STL). For more options, look at flights that include layovers.
What is the earliest flight from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.)?
The earliest flight from Denver International Airport (DEN) to Lambert-St. Louis International Airport (STL) typically departs at around 12:00 AM, operated by Frontier Airlines. This seasonal service is available in August, September, and October, allowing you to maximize your time in St. Louis. To compare early flights on Expedia, select the "Early Morning" and "Morning" filters in your search.
What are the most popular departure times for flights from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.)?
The most popular departure times for flights from Denver (DEN-Denver Intl.) to St. Louis (STL-Lambert-St. Louis Intl.) are in the early morning, from 6am to 9am. About 24% of passengers prefer this time window. Many major carriers, including American Airlines, Southwest Airlines, and Frontier Airlines, offer flights during this window. This timing is popular because it allows you to arrive in St. Louis with a full day ahead of you.
How long does it take to fly from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.)?
Flying nonstop from DEN to STL takes around 2 hours, with the route covering approximately 768 miles. Flights with a layover typically take 3 hours 50 minutes longer than direct options. Keep in mind that actual flight times can vary due to wind patterns, weather, and air traffic.
Can you fly business or first class from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.)?
You can fly first class between DEN and STL. First class cabins are available on:

  • Delta Air Lines
  • American Airlines
  • United Airlines

How much is a business class flight from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.)?
A direct, return business class ticket from Denver, CO (DEN) to St. Louis, MO (STL) typically costs between $911 - $1,454 per adult. Prices often fluctuate based on seasonality and how early you book. You may also be able to find a cheaper business class journey between Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.) if you opt for a connecting flight.*Prices based on flights available on Expedia in the last year.
How do I earn miles on a Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.) flight with Expedia?
It's easy to earn miles on a Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.) flight when you book with Expedia. Before you confirm your booking, simply select your frequent flyer program and enter your program number. As a member of One Key™, you can also earn OneKeyCash™* on top of your airline miles when you book with Expedia.*Excludes taxes and fees. OneKeyCash is not redeemable for cash and can only be used on Expedia and other participating brands.
What airports do you fly into for St. Louis from Denver Intl. (DEN)?
If you're planning to travel to St. Louis from Denver Intl. (DEN), you can fly into Lambert-St. Louis Intl. (STL) Some flights may connect through major hubs like Portland Intl. (PDX), Love Field (DAL), Eppley Field (OMA) before reaching St. Louis. Compare routes and airports on Expedia to find the best flight options for your travel plans.
Is it cheaper to buy a plane ticket from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.) at the last minute?
Typically, booking a last minute flight from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.) will be more expensive than booking in advance. As the departure date approaches, there are usually fewer seats available which can drive up the cost. However, if there's some wiggle room with your travel dates and times, you could bag a cheap last-minute fare.
Is it cheaper to book a Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.) flight and hotel package?
Securing a Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.) St Louis Vacation Packages is usually cheaper than booking separately. With Expedia, you can enjoy the ease of organizing your travels all in one place. Select from our extensive range of stays and then add flights, activities and car rentals to your booking. Bundle everything together, and you could save hundreds of dollars.
Can I cancel or change the date of my flight from Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.)?
If you booked your Denver, CO (DEN-Denver Intl.) to St. Louis, MO (STL-Lambert-St. Louis Intl.) flight within the last 24 hours, you may be able to modify or cancel it without any fees. Depending on the airline and the type of ticket you have, additional charges may apply for changes beyond this timeframe. Airline policies and contact information can be found in your itinerary or confirmation email. Or, head to our Customer Service portal if you'd like more information.

Travel information

Origin airport
Denver Intl.
Destination airport
Lambert-St. Louis Intl.
Airlines serving
Alaska Airlines, American Airlines, Delta, Frontier Airlines, Southwest Airlines, United
Roundtrip price
$80
Distance
767 mi
Average flight time
3 hours 2 mins

Book with confidence

Denver to St. Louis Flights

The cheapest times to fly from Denver to St. Louis

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from Denver to St. Louis are during the month of September. You can find some of the cheapest flights from Denver to St. Louis with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from Denver to St. Louis

Sunday is one of the best days to book for cheap flights from Denver to St. Louis: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

 

How to find cheap round-trip tickets from Denver to St. Louis

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from Denver to St. Louis in 2026. You can also book with separate airlines for your outbound and return journeys, from $40 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

 

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap Denver to St. Louis flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

 

You could also save big by booking one of Expedia's vacation packages. Bundling together your Denver to St. Louis airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

 

*Terms apply.

 

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

 

Denver to St. Louis Flights

*Flight schedules are subject to change.

*Available to One Key members.

 

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