DEN - STL

$40 Find Cheap Flights from Denver to St. Louis

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Denver to St. Louis departing on 3/25. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

KAYAK searches hundreds of travel sites at once for deals on flights to St. Louis

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Denver to St. Louis, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Denver to St. Louis, as well as popular online travel agencies
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Everything you should know

Cheapest round-trip
$79
Overall average: $285
Frontier
Fri 3/13Mon 3/16
DEN - STL • Non-stop
Cheapest one-way
$40
Typical prices: $87-$195
Frontier
Wed 3/25
DEN - STL • Non-stop
Our travelers' advice
AI-powered summary based on content written by travel experts. AI can make mistakes.
United's Wi-Fi includes free messaging on most flights.
Southwest offers two free checked bags for family travel.
Expert advice
Expert advice
Expert advice
Expert advice
Video guide: How to find cheap flights to St. Louis
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When to book
3 weeks
in advance
Our data shows that travelers who book at least 3 weeks in advance save around 18% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
January
Cheapest • 24% price drop
April
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
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KAYAK searches 100s of sites at once to find you the best travel deals.
We hope you love your trip to St. Louis!
Flight Deals
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Expert advice
Flight Deals

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

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Denver to St. Louis that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Denver to St. Louis

Fri, Mar 13 - Mon, Mar 16
Frontier Logo
6:35 am - 9:49 am
DEN
-
STL
2h 14mnonstop
Frontier Logo
8:12 pm - 9:49 pm
STL
-
DEN
2h 37mnonstop
$79Frontier
Fri, Feb 20 - Mon, Feb 23
Frontier Logo
10:01 am - 1:09 pm
DEN
-
STL
2h 08mnonstop
Frontier Logo
1:54 pm - 3:30 pm
STL
-
DEN
2h 36mnonstop
$80Frontier
Sat, Feb 28 - Mon, Mar 2
Frontier Logo
10:48 am - 1:56 pm
DEN
-
STL
2h 08mnonstop
Frontier Logo
8:22 pm - 11:56 am
STL
-
DEN
16h 34m
1 stop
$84Frontier
Sat, Mar 14 - Sat, Mar 21
Frontier Logo
6:35 am - 9:49 am
DEN
-
STL
2h 14mnonstop
Frontier Logo
8:12 pm - 9:49 pm
STL
-
DEN
2h 37mnonstop
$85Frontier
Sat, Feb 28 - Mon, Mar 2
Frontier Logo
10:48 am - 1:56 pm
DEN
-
STL
2h 08mnonstop
Frontier Logo
1:54 pm - 3:30 pm
STL
-
DEN
2h 36mnonstop
$87Frontier
Sat, Feb 21 - Wed, Mar 4
Frontier Logo
10:48 am - 1:56 pm
DEN
-
STL
2h 08mnonstop
Frontier Logo
5:18 pm - 6:53 pm
STL
-
DEN
2h 35mnonstop
$88Frontier
Sat, Mar 14 - Fri, Mar 20
Frontier Logo
6:35 am - 9:49 am
DEN
-
STL
2h 14mnonstop
Frontier Logo
8:12 pm - 9:49 pm
STL
-
DEN
2h 37mnonstop
$89Frontier
Fri, Feb 20 - Wed, Feb 25
Frontier Logo
10:01 am - 1:09 pm
DEN
-
STL
2h 08mnonstop
Frontier Logo
4:51 pm - 6:25 pm
STL
-
DEN
2h 34mnonstop
$92Frontier
Sat, Feb 21 - Wed, Feb 25
Frontier Logo
10:48 am - 1:56 pm
DEN
-
STL
2h 08mnonstop
Frontier Logo
4:51 pm - 6:25 pm
STL
-
DEN
2h 34mnonstop
$93Frontier
Wed, Feb 11 - Wed, Feb 18
Frontier Logo
10:50 am - 1:58 pm
DEN
-
STL
2h 08mnonstop
Frontier Logo
8:17 pm - 7:39 am
STL
-
DEN
12h 22m
1 stop
$98Frontier
Booking Insights

KAYAK's insights & trends for Denver to St. Louis flights

Get data-powered insights and trends into flights from Denver to St. Louis to help you find the cheapest flights, the best time to fly and much more.

Find cheap flights to St. Louis
Find cheap flights to St. Louis

Planning a trip from Denver to St. Louis? KAYAK’s data-powered insights will help you find cheap flights. Learn the best time to fly, how early to book your ticket, and other tips to secure great prices.

What’s the cheapest day of the week to fly from Denver to St. Louis?

The average price of all round-trip flights from Denver to St. Louis clicked on KAYAK for each day over the last 12 months.

When flying from Denver to St. Louis, you should consider leaving on a Friday and avoid Sundays if you are looking for the best rates. For your return to Denver, you’ll find the best rates on Wednesdays and the most expensive ones on Sundays.

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

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Denver to St. Louis, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from Denver to St. Louis is January, where tickets cost $181 (return) on average. On the other hand, the most expensive months are June and December, where the average cost of round-trip tickets is $297 and $287 respectively.

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

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from Denver to St. Louis, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.

To get a below average price on the flight from Denver to St. Louis, you should book around 3 weeks before departure, which saves you about 18% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 11 weeks before departure.

Expert advice

Expert advice for your flight from Denver to St. Louis

 
AI-powered summary based on content written by travel experts. AI can make mistakes.
KAYAK teamed up with top travel experts to share the best tips for your journey.
Our travel experts
Stefanie Waldek

Stefanie Waldek

Expert on Frontier and United Airlines

Stefanie Waldek is a freelance space, travel, and design writer based in Saratoga Springs, NY. Her words have appeared in Space.com, Travel + Leisure, Condé Nast Traveler, Architectural Digest, and House Beautiful, among other publications. An expert in aviation and expedition cruising, Stefanie is frequently up in the air or on the sea, likely en route to Antarctica or the Arctic.

Blane Bachelor

Blane Bachelor

Expert on Southwest

Blane Bachelor is a journalist and editor specializing in travel and aviation who writes regularly for top global outlets. Born and raised in Florida, Blane has worked and lived in four countries, including the Netherlands, where she’s currently based with her family. Her favorite way to get to know a new destination is by running or riding a bike around town – or hearing a spooky ghost story about local history. She will always choose the window seat.

Yulia Denisyuk

Yulia Denisyuk

Expert on STL

Yulia is a freelance journalist who’s dispatched from 90+ countries. Her work focuses on cultures, adventure trips and air travel, appearing in NatGeo, NYT, CNTraveler, and more. For past assignments, she’s stayed with nomads in Mongolia and learned the art of Imigongo in Rwanda. She’s based in Chicago; in winter she often questions that decision.

Harriet Baskas

Harriet Baskas

Expert on DEN

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.

Good to know

Low seasonNovember
Cheapest flight$40
Best time to beat the crowds but there is an average 8% increase in price.
Most popular time to fly with an average 3% increase in price.
Flight from Denver to St. Louis

When to book flights from Denver to St. Louis

Are your dates flexible? Find out the best times to travel from Denver to St. Louis based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking flights from Denver to St. Louis

  • Can I fly nonstop from Denver International Airport (DEN) to Lambert St Louis Airport (STL)?

    Yes, direct flights exist between Denver International Airport and Lambert St. Louis Airport. Multiple carriers, like Southwest Airlines and United Airlines, provide direct flights from DEN to Lambert Airport if you want to reach your destination quickly.

  • Is there public transportation to downtown from Lambert St Louis Airport?

    Yes, there is public transportation from Lambert St Louis to downtown. There are multiple options such as train, bus, or even taxi. Services run daily and leave every 20min. The travel time is roughly 30min.

  • Are there hotels at Lambert St Louis?

    Yes, there are quite a few hotel alternatives at and in close proximity to Lambert International Airport in St. Louis, including Hampton Inn St. Louis Airport and the Comfort Inn & Suites St. Louis-Hazelwood.

  • How can I get from one terminal to the other?

    STL Airport has a free 24h Terminal Shuttle that operates between Exit 12 at both terminals. There is currently no way to walk between terminals. Terminal 1 and Terminal 2 are less than one mile apart, thus the shuttle trip duration is roughly 10min. Every 8 to 15min, shuttles are scheduled to pick up passengers.

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

    In the last 3 days, the lowest price for a flight from Denver to St. Louis was $40 for a one-way ticket and $79 for a round-trip.

  • Do I need a passport to fly between Denver and St. Louis?

    Even though you are not required to have a passport, keep in mind that an official ID is needed to board the airplane.

  • Which airlines offer Wi-Fi service onboard planes from Denver to St. Louis?

    JetBlue, Delta, American Airlines, and Alaska Airlines offer inflight Wi-Fi service on the Denver to St. Louis flight route.

  • Which aircraft models fly most regularly from Denver to St. Louis?

    The Boeing 737 MAX 8 is the aircraft model that flies most regularly on the Denver to St. Louis flight route.

  • Which airline alliances offer flights from Denver to St. Louis?

    Star Alliance is the only airline alliance operating flights between Denver and St. Louis.

  • On which days can I fly direct from Denver to St. Louis?

    There are nonstop flights from Denver to St. Louis on a daily basis.

  • Which is the best airline for flights from Denver to St. Louis, Southwest or United Airlines?

    The two airlines most popular with KAYAK users for flights from Denver to St. Louis are Southwest and United Airlines. With an average price for the route of $304 and an overall rating of 8.0, Southwest is the most popular choice. United Airlines is also a great choice for the route, with an average price of $327 and an overall rating of 7.4.

  • How does KAYAK find such low prices on flights from Denver to St. Louis?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Denver to St. Louis.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Denver to St. Louis?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to St. Louis from Denver is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Denver to St. Louis?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to St. Louis with an airline and back to Denver with another airline. Booking your flights between Denver and STL can sometimes prove cheaper using this method.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Denver to St. Louis?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to St. Louis from Denver up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

KAYAK’s top tips for finding a cheap flight from Denver to St. Louis

  • Looking for a cheap flight? 25% of our users found flights on this route for $118 or less one-way and $133 or less round-trip.
  • Utilize the offered lounges at the departure and arrival airports. There are about six lounges at Denver International Airport (DEN) and a number of lounges at Lambert St. Louis (STL) that provide free food, drinks, showers, and high-speed Wi-Fi, among other services.
  • If you are departing from Denver International Airport (DEN) and need parking, there are numerous alternatives. You may use Valet Parking, which offers the best prices and reservations or choose one of the indoor or outdoor self-parking choices. They offer a range of amenities, including 24h staff and shuttles, wider, angled parking, free EV charging, and free roses.
  • When flying out of Denver International Airport, it is suggested that you arrive at the airport 2h before your flight's scheduled departure time. This should provide you with plenty of time to check-in for your flight, go through security, and make your way to your gate. If you visit the DEN website before you leave, you will be able to observe the wait times for the security lines in real-time, which will allow you to better prepare for your trip. Every single security checkpoint inside the DEN is always open and performing appropriately.
  • Free assistance for passengers traveling with wheelchairs is offered by airlines at both Denver International Airport (DEN) and Lambert St. Louis Airport (STL). Travelers with limited mobility or elderly passengers may find this to be of great assistance. Contacting the airline in advance to request a passenger help agent will get you the finest possible accommodations.
  • If you need to convert money at Lambert St Louis, go to the lower level of Terminal 1 and find the currency exchange counter near the C Gates security checkpoint. US Bank has a branch at the airport that provides comprehensive banking services as well as a currency exchange for international travelers. The business is open from Monday through Friday, starting at 8 am and closing at 5 pm.

Prefer to fly direct from Denver to St. Louis?

 
Direct data is based off flight results for the next 60 days. Find direct flights from all airlines flying direct from Denver Intl to Lambert-St Louis.
Find which airlines fly direct from Denver Intl Airport to Lambert-St Louis Airport, which days they fly and book direct flights.

Direct departures

Denver Intl to Lambert-St Louis

Monday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

Tuesday

Southwest, United Airlines

Southwest, United Airlines

Wednesday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

Thursday

Southwest, United Airlines

Southwest, United Airlines

Friday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

Saturday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

Sunday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

See more direct flights

Direct returns

Lambert-St Louis to Denver Intl

Monday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

Tuesday

Southwest, United Airlines

Southwest, United Airlines

Wednesday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

Thursday

Southwest, United Airlines

Southwest, United Airlines

Friday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

Saturday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

Sunday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

See more direct flights

Reviews of the top 3 airlines serving from Denver to St. Louis

 
See real verified KAYAK customer reviews for airlines flying from Denver to St. Louis. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Denver to St. Louis? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
SouthwestOverall score based on 4267 reviews
8.0Comfort
7.5Entertainment
8.1Boarding
7.0Food
8.6Crew
Airline reviews

All good except once again bags took an hour at Midway Airport Happens all the time. Ridiculous

10.0 ExcellentAnonymous, Jan 2026
PHX - MDW
Read more Southwest reviews

All good except once again bags took an hour at Midway Airport Happens all the time. Ridiculous

Everything went smoothly and we even arrived a little bit early.

Great vacation. Can't wait till next year for another one.

Great flight but super high price. Glad it was a business trip and not personal

On time. Friendly staff. Took to long to pre bord all the specialty groups. Cramped small plane

The seats were comfortable, and the boarding process was pretty smooth.

3 hour delay. Had to change plans and was still delayed.

The staff was very friendly, professional, and courteous. The overall flight was a great experience.

The crew canceled the complementary snack and drink in anticipation of turbulence that never materialized. I was counting on the drink (water) to take the the doses of medication - prescribed for my heart condition - that were due during the flight. Since no snack or meal was served on this flight, I cannot rate the food quality. Otherwise, this flight was excellent.

Departure was delayed more than 1/2 hour while we waited for luggage (only) transfer from another flight/plane. Once approved for takeoff, the flight was excellent.

Sitting on the runway after we land for almost two hours! Not sure if we should blame United or Just Dumpy Vance.

Flight was late - I was downgraded from first class to coach

Excellent flight. Smooth, efficient boarding. Quick flight. Arrived early at STL.

Crew seemed a bit cranky. No seatback screens. But boarding was efficient and on time and we arrived early.

See previous note about the passenger in Denver who threw my husband's bag out of the overhead bin in order to maker room for his own. And the flight attendant back up the new passenger.

Terrible. They wouldn't allow me on my flight on the 14th..

Impressed with the service despite turbulence because of the weather. Both flights arrived before their scheduled times.

Great experience…left a bit behind schedule but made up fir that in the air and landed 10 minutes early 😁

Electric plugs didn't work. Entertainment system wasn't working

The design of the light switch on the arm rest is ridiculous.

Very well recently! Frontier is improving and less harrassing customer on luggages! Positive!

Good for a budget airline! It was easy to get on, staff was really nice. Can’t say anything about the food or entertainment because it wasn’t available, which is fine.

I am writing to express my disappointment with my recent Frontier Airlines flight. I was charged $99 at the gate because my bag was said to be too large, yet once onboard there was no available overhead bin space, and I was required to place the bag under the seat in front of me anyway. This made the charge feel unnecessary and unfair. Additionally, before the flight even took off, I was asked to move from the seat I paid for into a middle seat so another passenger and her cat could have my seat to themselves. I was not offered compensation or an explanation for being moved from a paid seat. Between the unexpected bag fee and being forced to give up my seat, this experience fell well below acceptable customer service standards. I would appreciate a review of this situation and appropriate compensation.

It was costly and difficult to check in. $85 to take a small suitcase with me, carry on or checked and $75 on the return trip, Plus $25 if I didn't check my self in check in $25, because I couldn't do it on the kiosk. Small very uncomfortable seats, waited on the runway for near an hour each way. It was my worst flight to date.

It was ok. It was expensive to check 2 bags ($75.00 per bag), and then it took a long time to wait for shuttle to take us from one terminal to the terminal where the plane was taking off at LAX. And all of this for a flight where we had to pay for any food or drink that was not water.

It didn’t happen. I booked it and then was told it wasn’t available and then forced to pay far higher prices for a worse option

A 630departure flight Delayed 6hours! They changed my gate, I moved to the new gate. Had our flight on the screen for 12noon departure. I go get above to eat, check screen again and the flight was gone, no notice no announcement, nothing!! They sent my bag on the flight I wasn’t on, got it back to me 3days later. Thank goodness they did refund my money but I will NEVER fly them again.

Due to weather, my flight was delayed, further delayed, then canceled. I eventually got through to a support person who helped me find a different route out of MSP, but to get to DIA, they didn't want to, but eventually did help with the connection ticket purchase. But even this replacement flight was delayed time and time again, and I would have missed my connecting flights and I didn't want to get stuck in a layover city, so after 12 hours at the airport with two young boys who were very tired, we just cancelled our plans and spent the week at home, instead of Nana's.

Plane and crew on board were fine. Everything else was terrible.

The third party booking with cheapflightsfares was awful. Kayak should NOT partner with them. They sold me a bundle including seat selection and carry-on, but did not book the carry-ons with Frontier, so I’m out of pocket for $414 more while I await resolution.

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

Other airlines flying from Denver to St. Louis

Flights from the other most popular airlines that fly from Denver to St. Louis according to KAYAK users. Prices are the lowest found on KAYAK over the last 7 days. Price and availability are not guaranteed.