DEN - STL

$42 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 12/20. 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
Travelers love KAYAK
41,299,237 searches in the past 7 days on KAYAK

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Everything you should know

Cheapest round-trip
$101
Overall average: $232
Frontier
Wed 11/12Sat 11/15
DEN - STL • Non-stop
Cheapest one-way
$42
Typical prices: $117-$211
Frontier
Sat 12/20
DEN - STL • Non-stop
Our travelers' advice
AI-generated summary based on content written by travel experts
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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Top airlines
Frontier
Cheapest • from $101 (round-trip)
Southwest
Best reviews • 8.0 score
Airline reviews
Airline reviews
+1
+1
Airline reviews
Airline reviews
+1
When to book
2 weeks
in advance
Our data shows that travelers who book at least 2 weeks in advance save around 17% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
January
Cheapest • 23% price drop
November
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
Start a new search
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
Booking Insights
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

Wed, Nov 12 - Sat, Nov 15
Frontier Logo
6:00 am - 9:07 amDEN-STL
2h 07mnonstop
Frontier Logo
7:45 pm - 9:13 pmSTL-DEN
2h 28mnonstop
$101Frontier
Find Deal
Wed, Nov 12 - Sat, Nov 15
Frontier Logo
6:00 am - 9:07 amDEN-STL
2h 07mnonstop
Frontier Logo
4:51 pm - 3:59 amSTL-DEN
12h 08m1 stop
$106Frontier
Find Deal
Sat, Dec 13 - Sat, Jan 3
Frontier Logo
7:05 am - 10:14 amDEN-STL
2h 09mnonstop
Frontier Logo
7:43 pm - 9:15 pmSTL-DEN
2h 32mnonstop
$107Frontier
Find Deal
Thu, Nov 13 - Sat, Nov 15
Frontier Logo
8:40 am - 5:27 pmDEN-STL
7h 47m1 stop
Frontier Logo
4:51 pm - 3:59 amSTL-DEN
12h 08m1 stop
$110Frontier
Find Deal
Mon, Nov 17 - Wed, Nov 19
Frontier Logo
6:00 am - 9:07 amDEN-STL
2h 07mnonstop
Frontier Logo
7:45 pm - 9:13 pmSTL-DEN
2h 28mnonstop
$111Frontier
Find Deal
Sat, Nov 15 - Sat, Nov 15
Frontier Logo
6:00 am - 3:56 pmDEN-STL
8h 56m1 stop
Frontier Logo
7:45 pm - 9:13 pmSTL-DEN
2h 28mnonstop
$114Frontier
Find Deal
Fri, Dec 5 - Mon, Dec 8
Frontier Logo
7:05 am - 10:14 amDEN-STL
2h 09mnonstop
Frontier Logo
12:07 pm - 12:20 amSTL-DEN
13h 13m1 stop
$116Frontier
Find Deal
Mon, Jan 12 - Wed, Jan 14
Frontier Logo
7:33 am - 4:49 pmDEN-STL
8h 16m1 stop
Frontier Logo
7:43 pm - 9:15 pmSTL-DEN
2h 32mnonstop
$117Frontier
Find Deal
Wed, Nov 12 - Fri, Nov 14
Frontier Logo
6:00 am - 9:07 amDEN-STL
2h 07mnonstop
Frontier Logo
7:45 pm - 9:13 pmSTL-DEN
2h 28mnonstop
$120Frontier
Find Deal
Mon, Jan 12 - Wed, Jan 14
Southwest Logo
9:10 am - 12:20 pmDEN-STL
2h 10mnonstop
Southwest Logo
6:20 am - 7:50 amSTL-DEN
2h 30mnonstop
$162Southwest
Find Deal
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 $178 (return) on average. On the other hand, the most expensive months are June and March, where the average cost of round-trip tickets is $297 and $277 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 2 weeks before departure, which saves you about 17% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 19 weeks before departure.

Expert advice

Expert advice for your flight from Denver to St. Louis

 
Snippets provided in this section are AI-generated based on a summarization of KAYAK-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.
KAYAK teamed up with top travel experts to share the best tips for your journey.
Airlines
Frontier

Avoid airport check-in fees by using the Frontier app or kiosk for free check-in.


Purchase priority boarding to ensure overhead bin space for your carry-on.

Read more about Frontierby Stefanie Waldek
Southwest

Southwest offers free carry-on and personal item, but checked bags now incur fees.


Southwest's Rapid Rewards program offers unlimited rewards seats and no blackout dates.

Read more about Southwestby Blane Bachelor
United Airlines

United offers Wi-Fi on most flights, with free messaging available.


Economy Plus seats provide up to six inches more legroom than standard economy.

Airports
DEN

Use the West Security Checkpoint at DEN for faster screening; it allows liquids and laptops to stay in bags.

Read more about DENby Harriet Baskas
STL

Take the MetroLink Red Line from STL for easy access to downtown St. Louis and popular areas like Delmar Loop.

Read more about STLby Yulia Denisyuk
Our travel experts
Stefanie Waldek

Stefanie Waldek

Expert on Frontier and United Airlines

Stefanie Waldek

Stefanie Waldek

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.

Read more
Blane Bachelor

Blane Bachelor

Expert on Southwest

Blane Bachelor

Blane Bachelor

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.

Read more
Yulia Denisyuk

Yulia Denisyuk

Expert on STL

Yulia Denisyuk

Yulia Denisyuk

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.

Read more
Harriet Baskas

Harriet Baskas

Expert on DEN

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

Good to know

Low seasonJanuary
Cheapest flight$42
Best time to beat the crowds with an average 23% drop in price.
Most popular time to fly and prices are also 0% lower on average.
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 $42 for a one-way ticket and $101 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?

    Delta, JetBlue, 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 $298 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 $326 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 $109 or less one-way and $197 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

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

Wednesday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

Thursday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

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

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

Wednesday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

Thursday

Frontier, Southwest, United Airlines

Frontier, Southwest, +1 more

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 4243 reviews
8.6Crew
7.5Entertainment
7.0Food
8.1Boarding
8.0Comfort
Airline reviews

Ever since Southwest starting charging for bags, passengers don't want to pay to check their bags, so the gate agents have to beg people to check their roller bags now because there's "not enough space". This was a terrible business move by Southwest.

8.0 ExcellentGreg, Oct 2025OAK - BUR
Read more Southwest reviews

Ever since Southwest starting charging for bags, passengers don't want to pay to check their bags, so the gate agents have to beg people to check their roller bags now because there's "not enough space". This was a terrible business move by Southwest.

Full cans of soda would be nice. A choice between two snacks would be appreciated.

Tried watching free movie and it kept freezing so I couldn’t finish.

All was good. I just had a hard time getting connected to the WiFi/internet during the flight

Sacrament staff are always polite and helpful. Airport is easy to maneuver and boarding is straightforward.

Great flight. Outstanding Service. Southwest was able to put us on a direct flight to Denver when the connection could have been affected by a later arrival to Baltimore. The direct flight was less expensive that the flight with the connection in Baltimore.

Boarded on time but once we were ready for take off, the crew determined that, although every seat was taken, somehow someone was on the wrong flight. Delay, delay delay, announcements and ended up with one person checking EVERY ID against their passenger Manifest only to figure out it was a "clerical error." We departed 54 minutes late causing me to run in the St. Louis Airport to make my connection and lose the priority boarding spot I had paid for. Unnecessary delay.

Flight was delayed due to plane not passing inspection And one of the crew had to time out and we had to wait for another one A 3 hour delay

Connecting flight is on time and boarding was a breeze!

Southwest's seats are the least comfortable I have ever sat in.

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.

The gate attendant let me walk right by her with a bag too big for the overhead compartment

Overall, it was a good experience. Boarding was good and there was plenty of overhead bin space for everyone’s carryons (even when we boarded toward the end). Only improvement would be to offer trash service more regularly.

Terrible. Flight cancelled with no reasoning and no flights to rebook. Employees were useless and did nothing to help. Did not even know where to retrieve luggage from the cancelled flight. Flyers beware.

No fault of Frontier staff: plane was very late, reached Orlando at 1 am, took a while to get luggage. Weather, gov financial shutdown impact on TSA, air controllers seemed to have multiple flights backed up. Frontier staff seemed to cope as gracefully as possible. It did reassure me that I and my new hip could adapt to travel challenges. Food/entertainment were irrelevant to my trip.

Terrible. The canceled my entire flight when I requested a refund for a trip frontier canceled trip one way.

Boarding was on time and plane departed as scheduled. There are obviously no amenities (food, drink, entertainment) on Frontier, but there also didn't seem to be any issues with luggage space either.

Inbound plane was on time and flight departed on time with no issues while boarding.

I knew going into this that Frontier, being a low cost carrier, would be pretty bare bones and charge for most extras but this was made up for by the fact that the airplane was a reasonably new Airbus, every employee was great and best of all, Everett Washington is an amazing airport - thanks Frontier for flying there!!!

Frontier is the Walmart of airlines. Frontier has removed adjustability and comfort from their seats to make the flight lighter and save gas. This makes it impossible to sleep on their flights. Their customer service is abysmal. Once, I bought a drink on the plane, and they swiped my credit card on the plane to pay for it. Then I got three weeks of daily notices from my bank telling me they tried to charge the wrong card number over and over again. I tried to call them, but they removed the ability to actually talk to someone that can resolve such a problem from their company to cut corners. The only way to talk to someone in person is to go to the check-in counter at the airport (40 minutes drive from my house). Eventually their system gave up on trying to charge the card, after 21 days of repeated tries. They don't pad their prices even a little to handle customer service issues like missed flights. They also have a blanket policy preventing helping you reschedule a missed flight if their system says you "cancelled" your own flight online. This is a major problem because their website is broken on mobile devices, the only web browser you have at the airport when their gate staff tell you that you have to reschedule your own missed flight online because they can't help you. I tried to reschedule my flight on my android device and instead, their website crashed and "cancelled" my missed flight. When I got to the counter, the agent argued with me for 5 minutes insisting that I intentionally cancelled my own flight (implying I had to buy another flight). She missed the point: the problem was that I could not buy another flight because their website is broken. I left to avoid more conflict with the "customer service" agent. I tried to redress my issue with their only other "customer service" chanel available: the contact form on their website. The response I got was more of the same: you cancelled your own flight, according to our website / computer records, therefore we won't help you. I was trying to explain the problem with their broken website that cost me hundreds of dollars by crashing / malfunctioning and resulting in a cancelled flight, but they only had deaf ears for this problem. Worst customer service I have ever experienced. I will never buy another Frontier flight again, because it is a risky, painful move that I will likely regret often.

What I expected, nickeled and dined and a frontier flight attendant loudly complained about her job and lack of communication as she headed to the gate on her cell phone. Not professional.

I’m not gonna fly Frontier Airlines because booking is not an option. No water or food is for high price, not equipped for health emergency incompetent crew for emergency services. Cheap airline shows it is cheaper in all service categories. Boarding is the best of all airlines!

Very bad! No good service delayed my second connection flight

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.

Compare transportation modes for Denver to St. Louis

Transportation modeAverage priceAverage duration
Flights$5192h 07m
Buses$16516h 30m

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