$55 Cheap Flights from Denver (DEN) to St. Louis (STL)

View $55 flight on Sat, Oct 4, 2025Opens 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 $55 for one-way flights and $99 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Frontier Airlines
Tue, Oct 28 - Sat, Nov 1
DEN
Denver
STL
St. Louis
$99 Roundtrip, found 13 hours ago
$99
Roundtrip
found 13 hours ago
Select Frontier Airlines flight, departing Tue, Oct 28 from Denver to St. Louis, returning Sat, Nov 1, priced at $99 found 13 hours ago
Frontier Airlines
Sat, Aug 23 - Tue, Aug 26
DEN
Denver
STL
St. Louis
$111 Roundtrip, found 1 hour ago
$111
Roundtrip
found 1 hour ago
Select Frontier Airlines flight, departing Sat, Aug 23 from Denver to St. Louis, returning Tue, Aug 26, priced at $111 found 1 hour ago
Frontier Airlines
Wed, Nov 12 - Wed, Nov 19
DEN
Denver
STL
St. Louis
$114 Roundtrip, found 4 hours ago
$114
Roundtrip
found 4 hours ago
Select Frontier Airlines flight, departing Wed, Nov 12 from Denver to St. Louis, returning Wed, Nov 19, priced at $114 found 4 hours ago
Frontier Airlines
Sat, Oct 11 - Tue, Oct 21
DEN
Denver
STL
St. Louis
$117 Roundtrip, found 2 hours ago
$117
Roundtrip
found 2 hours ago
Select Frontier Airlines flight, departing Sat, Oct 11 from Denver to St. Louis, returning Tue, Oct 21, priced at $117 found 2 hours ago
Frontier Airlines
Sat, Sep 13 - Fri, Sep 19
DEN
Denver
STL
St. Louis
$122 Roundtrip, found 10 hours ago
$122
Roundtrip
found 10 hours ago
Select Frontier Airlines flight, departing Sat, Sep 13 from Denver to St. Louis, returning Fri, Sep 19, priced at $122 found 10 hours ago
Frontier Airlines
Tue, Sep 2 - Fri, Sep 12
DEN
Denver
STL
St. Louis
$128 Roundtrip, found 2 hours ago
$128
Roundtrip
found 2 hours ago
Select Frontier Airlines flight, departing Tue, Sep 2 from Denver to St. Louis, returning Fri, Sep 12, priced at $128 found 2 hours ago
Southwest Airlines
Wed, Nov 12 - Wed, Nov 19
DEN
Denver
STL
St. Louis
$134 Roundtrip, found 4 hours ago
$134
Roundtrip
found 4 hours ago
Select Southwest Airlines flight, departing Wed, Nov 12 from Denver to St. Louis, returning Wed, Nov 19, priced at $134 found 4 hours ago
Delta
Wed, Nov 12 - Wed, Nov 19
DEN
Denver
STL
St. Louis
$154 Roundtrip, found 4 hours ago
$154
Roundtrip
found 4 hours ago
Select Delta flight, departing Wed, Nov 12 from Denver to St. Louis, returning Wed, Nov 19, priced at $154 found 4 hours ago
American Airlines
Sat, Sep 20 - Tue, Sep 30
DEN
Denver
STL
St. Louis
$155 Roundtrip, found 2 hours ago
$155
Roundtrip
found 2 hours ago
Select American Airlines flight, departing Sat, Sep 20 from Denver to St. Louis, returning Tue, Sep 30, priced at $155 found 2 hours ago
United
Sat, Oct 25 - Tue, Nov 4
DEN
Denver
STL
St. Louis
$157 Roundtrip, found 2 hours ago
$157
Roundtrip
found 2 hours ago
Select United flight, departing Sat, Oct 25 from Denver to St. Louis, returning Tue, Nov 4, priced at $157 found 2 hours ago

Find the cheapest month to fly from Denver (DEN) to St. Louis (STL)

September is typically the cheapest month to fly

From $48 - $132 per traveler.

Graph displaying average flight prices per month

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 $208
STL
Lambert-St. Louis Intl.
Cheapest
Average driving time to city center20 min
Flights from $208
Flights from Denver (DEN) to St. Louis (STL)
Origin airport
Denver Intl.
Destination airport
Lambert-St. Louis Intl.
Airlines serving
Alaska Airlines, American Airlines, Delta, Frontier Airlines, Southwest Airlines, United
Roundtrip price
$92
Distance
767 mi
Average flight time
3 hours 5 mins

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 October. 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 2025. You can also book with separate airlines for your outbound and return journeys, from $55 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.

 

Frequently asked questions

How much does a flight from Denver Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL) cost?
You can find cheap return flights from Denver Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL) starting at $107. Book a seat and take off on your trip. This information is based on the cheapest price found on Expedia for this return journey departing within the next three months. This airfare is for a Frontier Airlines flight leaving DEN on August 19 2025 and touching down at STL. The price was last updated on July 23 2025 and has not changed since.
What is the cheapest month to fly from DEN to STL?
The cheapest flights from DEN to STL are usually during off-peak season, when demand is lower. To save money, avoid flying during public holidays, school breaks and major local events.
Which airlines fly direct from Denver Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL)?
You can choose from 3 airlines that fly directly from Denver Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL). These include:

  • Southwest Airlines
  • United Airlines
  • Frontier Airlines

What is the cheapest airline that flies from DEN to STL?
With tickets starting at $62 for a one-way flight from DEN to STL, Frontier Airlines is currently the cheapest carrier operating this route. This fare is based on the lowest price found on Expedia departing within the next three months. The flight takes off from DEN on September 25 2025. Prices were last updated on July 23 2025 and have not changed since.
How many flights per day from Denver Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL)?
With, on average, 8 direct flights that operate from Denver Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL) daily, you'll be cruising above the clouds before you know it.
What are the most popular departure times for flights from Denver Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL)?
Flights between DEN and STL are busiest at 9 AM. If you're after a more relaxed trip and potentially cheaper prices, choose a departure outside the usual busy windows.
What day of the week has the most flights from DEN to STL?
If you depart on a Monday, you'll get the largest range of choices for flights from Denver Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL).
What is the earliest flight from Denver Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL)?
The earliest flight taking off from Denver Intl. Airport (DEN) is at around 6:00AM UTC-7. Catch this flight and you'll touch down at Lambert-St. Louis Intl. Airport (STL) at approximately 9:16AM UTC-6. The total travel time is 2h 16m.
How long does it take to fly from Denver Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL)?
Flights from DEN to STL have an average travel time of 2 hours and 5 minutes. The distance between the two is 770 mi.
What airline has the least delays from DEN to STL?
Frontier Airlines has the best track record for on-time direct flights from Denver Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL), with an on-time score of 80%. Use the Expedia App to view your flight status before you leave and receive notifications about any trip changes.
What is the best time to fly from Denver Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL)?
To land at Lambert-St. Louis Intl. Airport (STL) on schedule, opt for a flight that leaves from Denver Intl. Airport (DEN) before 3 PM. The chance of cancellations is 22% higher, on average, for departures after this time.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
What airports do you fly into for St. Louis from Denver Intl. Airport (DEN)?
If you've booked a direct flight from Denver Intl. Airport (DEN) to St. Louis, Lambert-St. Louis Intl. Airport (STL) is the only airport you can touch down at.
Is it cheaper to buy a plane ticket from Denver Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL) last-minute?
Booking your ticket from DEN to STL right before your journey is typically more expensive. However, if you're flexible with your travel times and dates, you could score a cheap last-minute fare.
Is it cheaper to book a DEN to STL flight and hotel package?
Securing a DEN to STL flight and hotel package is typically cheaper than booking separately. With Expedia, you can enjoy the ease of organizing your travels all in one place. Choose from our wide range of hotels and then add flights, car rentals and activities 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 Intl. Airport (DEN) to Lambert-St. Louis Intl. Airport (STL)?
You can usually reschedule or cancel your DEN to STL flight. However, if it's been more than 24 hours since booking, additional charges may apply. Check your airline's policies in your itinerary to see what changes are allowed and whether any costs are involved. You'll also find more details on our Customer Service portal.

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