Cheap Flights from St Louis (STL) to Denver International (DEN)

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Flight deals from St Louis to Denver International

Looking for a cheap last-minute deal or the best return flight from St Louis to Denver International? Find the lowest prices on one-way and return tickets right here.

Find the cheapest month to fly from St Louis to Denver International

We’re always keeping an eye on fares, so you can find the best one in seconds. It looks like St Louis to Denver International flights are currently cheapest in April.

Direct flights from St Louis to Denver International

St Louis to Denver International: Alternative routes

Compare routes from St Louis to Denver below. You may find an airport to fly into that's cheaper, faster, or easier than Denver International.

St Louis to Denver: Flight information

The things to know before you go.
Cheapest flight found£41
Cheapest month to flyApril
Average flight time2 hrs, 26 mins
Most popular airlineSouthwest Airlines
Average flights per week121

Finding cheap flights from St Louis to Denver International: Frequently asked questions

The best price we found for a return flight from St Louis to Denver International is £41. This is an estimate based on information collected from different airlines and travel providers over the last 4 days and is subject to change and availability.
2 hours and 26 minutes is the average flight time from St Louis to Denver International.
Southwest Airlines, United and Air Canada fly direct from St Louis to Denver International.
As of February 2026, there are 122 flights per week flying from St Louis to Denver International.
The cheapest month to fly from St Louis to Denver International is usually April.
After crunching the numbers on our flight calendar, we found that it's currently cheapest to fly from St Louis Airport to Denver International Airport on Saturday, 18 April 2026.
Yes – the average flight time is 2 hours and 26 minutes.
We show every price from over 1,200 airlines and travel agents, comparing them all so you don’t have to. If you know you want to fly to Denver International but you’re not ready to book, set up a Price Alert. We’ll track prices for you, and let you know when they rise or fall.
We crunched all the numbers in our flight calendar and it looks like the cheapest time to book a flight to Denver is around 40 days in advance, so don’t leave your flight to the last minute.
Currently, Frontier Airlines offers the cheapest flight tickets to Denver International.

Flying from Lambert-St. Louis International Airport (STL) to Denver International Airport (DEN): what you need to know

  • Around 2 hours 25 minutes is how long you can expect to be travelling on a direct flight from Lambert-St. Louis International Airport to Denver International Airport.

  • Denver is one hour behind St Louis and observes the UTC-6 timezone.

  • Each week, there are 78 Lambert-St. Louis International Airport to Denver International Airport flights. If you'd like to get going early, jump on the 05:15 Southwest Airlines flight. If you'd rather make the most of your time before flying, the last departure is at 22:59 with Frontier Airlines.

  • Your STL to DEN flight won't wait if you're late, so show up at the airport on time. Arrive up to one hour in advance for domestic flights and two hours ahead when you're flying internationally.

  • During popular months such as July, it's a good idea to get to the airport well in advance. Arrive two hours before a domestic departure and four hours ahead of international flights when you travel during a peak period in general.

  • With direct flights from Lambert-St. Louis International Airport to Denver International Airport available from numerous airlines, getting to Denver (and then other parts of United States) is a cinch. You can fly nonstop with:

  • Frontier Airlines is the airline with the highest passenger demand for this route.

  • Frontier Airlines is a leader in on-time performance for STL to DEN flights, with 81.63% of its services arriving on schedule.

  • We make it a breeze to book a flight with a stopover. To see all your options for tickets from Lambert-St. Louis International Airport to Denver International Airport, deselect 'Direct flights only.' Then, pick a flight that has a stop long enough to visit the city of your choice. Worthwhile stopovers between STL and DEN include:

    • Kansas City International Airport

    • Dallas Love Field Airport

    • Minneapolis-St. Paul International Airport

How to find the cheapest flights from Lambert-St. Louis International Airport (STL) to Denver International Airport (DEN)

  • The cheapest price we've found for a one-way Lambert-St. Louis International Airport to Denver International Airport flight is £21. A return fare is currently £41. Depending on the availability and when you book, these fares could change.

  • To get cheap tickets from STL to DEN, reserve your trip six months before your departure.

  • Plan your trip for May. That's the cheapest month for flights from Lambert-St. Louis International Airport to Denver International Airport. If you're flexible with your dates, use the 'Whole month' tool to find the cheapest airfare across each month.

  • Snapping up cheap flights from STL to DEN is a piece of cake with Price Alerts. All you need to do is set up one of these automatic alerts and we'll let you know as soon as there's a better deal.

  • Secure the ideal flight for you with the help of the filters. To see the 'Fastest,' 'Best' or 'Cheapest' flights from Lambert-St. Louis International Airport to Denver International Airport, use the 'Sort by' function. You can also filter results by arrival and departure times, airline, and number of stops.

Handy information about Lambert-St. Louis International Airport (STL)

Arriving at Denver International Airport (DEN)

  • Consider checking in to Baymont by Wyndham Denver International Airport after your Lambert-St. Louis International Airport to Denver International Airport flight. It's a quick drive from DEN and a comfy option if you're eager to freshen up right away.

  • Pick up a Denver International Airport rental car and explore Denver and beyond with your own wheels. Routes Car Rentals, Dollar and Budget are popular providers to choose from here.

  • To get the lowest price, book your ride from Denver International Airport around one week before you travel.

Getting from Denver International Airport (DEN) to central Denver

  • You'll find DEN at 8500 Pena Boulevard.

  • Denver International Airport is approximately 25 miles from central Denver. The drive time takes around 35 minutes.

  • When travelling on public transport, expect a journey of about 1 hour 30 minutes.

When to fly to Denver International Airport (DEN)

  • July is the busiest month for flights from Lambert-St. Louis International Airport to Denver International Airport. To escape the crowds, travel to Denver in April.

  • Lock in your flight from Lambert-St. Louis International Airport to Denver International Airport for July if you'd like to go to Denver during its warmest month. You can expect temperatures of between 14ºC (57ºF) and 32ºC (90ºF).

  • If you'd rather travel in cooler conditions, search for a cheap ticket from STL to DEN in January. Average temperatures are between -9ºC (16ºF) and 7ºC (45ºF) then.

Explore more of United States

  • You've done Denver, now it's time to explore more of United States. Journey about 65 miles south to Colorado Springs to check off its top attractions. From US Northern Command (USNORTHCOM) / North American Aerospace Defence Command (NORAD) Headquarters to Cheyenne Mountain Air Force Station and National Strength and Conditioning Association (NSCA), you've got a jam-packed schedule ahead.

  • If you want to check out another side of United States, head for Aurora, about 8 miles east of Denver. Magellan's Travel Solutions and Gear, The Fairways at Lowry and Retired Enlisted Association Inc are among its highlights.

Prices shown on this page are estimated lowest prices only. Found in the last 45 days.