$35 Cheap flight deals from St. Louis (STL) to Boulder (DEN)

Earn rewards on top of your airline miles with Orbitz Rewards

Many airlines offer flexible change policies

Sign up to receive text alerts about your trip

This Weekend's Flight Deals from St. Louis to Boulder

This weekend's flight prices found within the past 7 days, for the period specified. Prices and availability are subject to change. Additional terms apply.

Sat, Jul 5 - Mon, Jul 7
STL
Lambert-St. Louis Intl.
DEN
Denver Intl.
$129 Roundtrip, found 1 hour ago
$129
Roundtrip
found 1 hour ago
Select Frontier Airlines flight, departing Sat, Jul 5 from Lambert-St. Louis Intl. to Denver Intl., returning Mon, Jul 7, priced at $129 found 1 hour ago
Fri, Jul 4 - Sun, Jul 6
STL
Lambert-St. Louis Intl.
FNL
Fort Collins-Loveland Municipal
$592 Roundtrip, found 9 hours ago
$592
Roundtrip
found 9 hours ago
Select United flight, departing Fri, Jul 4 from Lambert-St. Louis Intl. to Fort Collins-Loveland Municipal, returning Sun, Jul 6, priced at $592 found 9 hours ago

Airfares from $35 One Way, $68 Round Trip from St. Louis to Boulder

Prices starting at $68 for return flights and $35 for one-way flights to Boulder were the cheapest prices found within the past 7 days, for the period specified. Prices and availability are subject to change. Additional terms apply.

Sat, Oct 25 - Tue, Oct 28
STL
St. Louis
DEN
Denver
$68 Roundtrip, found 7 hours ago
$68
Roundtrip
found 7 hours ago
Select Frontier Airlines flight, departing Sat, Oct 25 from St. Louis to Denver, returning Tue, Oct 28, priced at $68 found 7 hours ago
Sat, Aug 16 - Sat, Aug 23
STL
St. Louis
DEN
Denver
$69 Roundtrip, found 6 hours ago
$69
Roundtrip
found 6 hours ago
Select Frontier Airlines flight, departing Sat, Aug 16 from St. Louis to Denver, returning Sat, Aug 23, priced at $69 found 6 hours ago
Sat, Oct 4 - Mon, Oct 6
STL
St. Louis
DEN
Denver
$78 Roundtrip, found 8 hours ago
$78
Roundtrip
found 8 hours ago
Select Frontier Airlines flight, departing Sat, Oct 4 from St. Louis to Denver, returning Mon, Oct 6, priced at $78 found 8 hours ago
Thu, Sep 4 - Wed, Sep 10
STL
St. Louis
DEN
Denver
$157 Roundtrip, found 6 hours ago
$157
Roundtrip
found 6 hours ago
Select Southwest Airlines flight, departing Thu, Sep 4 from St. Louis to Denver, returning Wed, Sep 10, priced at $157 found 6 hours ago
Wed, Dec 10 - Thu, Dec 18
STL
St. Louis
DEN
Denver
$157 Roundtrip, found 3 hours ago
$157
Roundtrip
found 3 hours ago
Select United flight, departing Wed, Dec 10 from St. Louis to Denver, returning Thu, Dec 18, priced at $157 found 3 hours ago

Boulder economy flight packages

Price found within the past 48 hours. Click for updated prices.
The Maven Hotel at Dairy Block
4.0-star property

The Maven Hotel at Dairy Block

9.4/10 Exceptional! (1,094 reviews)

Aug 9 - Aug 13

4 night stay

St. Louis (STL) to Denver (DEN)

Frontier Airlines • Roundtrip • Coach
Save 100% on your flight
per person
found 1 day ago
Great vibe. Unique.

Reviewed on Oct 27, 2024

The Crawford Hotel
5.0-star property

The Crawford Hotel

9.2/10 Wonderful! (1,006 reviews)

Aug 9 - Aug 13

4 night stay

St. Louis (STL) to Denver (DEN)

Frontier Airlines • Roundtrip • Coach
Save 100% on your flight
per person
found 1 day ago
Great location and cool hotel.

Reviewed on May 26, 2025

The Oxford Hotel
4.0-star property

The Oxford Hotel

9.4/10 Exceptional! (1,001 reviews)

Aug 19 - Aug 24

5 night stay

St. Louis (STL) to Denver (DEN)

Frontier Airlines • Roundtrip • Coach
Save 100% on your flight
per person
found 8 hours ago
My room looked out onto 17th, but was so quiet. Loved the bed and the large gracious room! The continental breakfast was so much better than a few pastries and some coffee—lox, cream cheese, yogurt…a respectable breakfast with protein! The best part was taking the lite rail from the airport and walking across the street with my bag to the Oxford! All around, a great place to stay!

Reviewed on Apr 7, 2025

Don't see what you're looking for?
See all available trips from St. Louis to Boulder
View all trips

Boulder first class flight packages

Price found within the past 48 hours. Click for updated prices.
The Art Hotel Denver, Curio Collection by Hilton
4.5-star property

The Art Hotel Denver, Curio Collection by Hilton

8.6/10 Excellent! (1,000 reviews)

Aug 9 - Aug 13

4 night stay

St. Louis (STL) to Denver (DEN)

United • Roundtrip • FirstClass
per person
found 1 day ago
It's a cool hotel. Tons of art pieces and sculptures. Hotel bar was good, tasty drinks- we were able to use our resort fee to get drinks. Got free upgrade which was awesome. Downside was - 1. not safe to walk around and lot of construction in the area 2. AC wasn't working best in the room unfortunately.

Reviewed on Aug 6, 2023

The Rally Hotel at McGregor Square
4.0-star property

The Rally Hotel at McGregor Square

9.6/10 Exceptional! (1,386 reviews)

Aug 9 - Aug 13

4 night stay

St. Louis (STL) to Denver (DEN)

United • Roundtrip • FirstClass
per person
found 1 day ago
The property is great and many places to go in walking distance.

Reviewed on Apr 22, 2025

Warwick Denver
4.0-star property

Warwick Denver

8.2/10 Very Good! (1,611 reviews)

Aug 9 - Aug 13

4 night stay

St. Louis (STL) to Denver (DEN)

United • Roundtrip • FirstClass
per person
found 1 day ago
I stay here anytime I visit Colorado and love the hotel. The breakfast is delicious, the drinks at the bar at good, it's in a safe area, and I never have any issues

Reviewed on Jun 24, 2025

Don't see what you're looking for?
See all available trips from St. Louis to Boulder
View all trips

More About Flying To Boulder from St. Louis

Route Information for Flights from St. Louis to Boulder

Origin Airport IATA Code
STL
Destination Airport IATA Code
DEN
Distance
767 mi
Direct Flight Airlines
Air Canada, Frontier Airlines, Southwest Airlines, United Airlines
Earliest Flight Arrival
12:52PM UTC
Latest Flight Arrival
2:56AM UTC

St. Louis to Boulder

Orbitz is the best place to find guaranteed low prices on St. Louis to Boulder flights. Because of our cutting-edge mobile tools and low fares on domestic and international flights, Orbitz is the best starting point for travelers.

Find Cheap St. Louis to Boulder Flights

Orbitz offers free mobile apps for iPhone and Android devices—a great way to find fantastic deals on flights from St. Louis to Boulder. Not only that, but you can check the status of your flight or even book low cost hotel rooms with the apps or on m.orbitz.com.

Get Miles and Points for Your Flight

Simply enter your frequent flyer information while booking to get miles or points for qualifying St. Louis to Boulder flights. This information can all be saved in your Orbitz account, which means it will not have to be entered each time you take advantage of a great air fare deal.

Flight Alerts Take Away the Stress

Orbitz does not want travelers to worry on their flights from St. Louis to Boulder. We keep you updated on any flight changes for St. Louis to Boulder flights with alerts sent directly to your email or a mobile device. These alerts can also be sent to friends and family.

Discount Travel Planning Made Simple

You will have no problems finding budget flights from St. Louis to Boulder on Orbitz.com. If your travel plans are flexible, you can search for fares three days before and after a specific date to find the best price.

Frequently asked questions

Are there non-stop flights from St. Louis to Boulder?
There certainly are. In fact, there are 3 airlines that will fly you directly from Lambert-St. Louis Intl. Airport (STL) to DIA airport. Book your ticket with one of these popular carriers:

  • Southwest Airlines
  • United Airlines
  • Frontier Airlines

What is the shortest flight from St. Louis to Boulder?
It can take as little as 2 hours and 15 minutes to jet from Lambert-St. Louis Intl. Airport (STL) to DEN. Relax and enjoy those window views, because you'll be landing in a heartbeat.
What airlines fly from St. Louis to Boulder most frequently?
Take a look at Southwest Airlines (WN). This airline offers some of the most frequent flights from STL to Denver, CO (DEN-Denver Intl.). It operates 160 services on this route each month and is a favorite among travelers. Also explore the rewarding deals from United Airlines (UA). Offering 121 flights each month between St. Louis and Boulder, they'll ensure your journey is just as enjoyable as the destination.
What is the cheapest day of the week to fly?
Consider flying out early in the week to save on your airfare. Orbitz data from 2021 shows that Monday is the cheapest day to depart, followed by Tuesday. Saturday showed the highest average ticket prices likely because many travelers prefer to start their vacation on a weekend.
What is the cheapest month to fly?
We won't keep you guessing, according to Orbitz data from 2021, the cheapest month to fly is February. Perfect for those who need a weekend getaway, or just a break from it all in the shortest month of the year. Be aware that the most expensive time to fly is during the height of summer in July, and in the holiday month of December.*According to flight demand on Orbitz.com from January to December 2021. Savings are subject to change based on departure location, date and destination.

Fare, taxes & fees: Fares include all taxes and fees, except baggage fees. Rates shown reflect fares found by other Orbitz users over the past 7 days. Due to rapidly changing airline prices & seat availability, these fares may no longer be available.

Refunds/changes/cancellations: Itinerary changes, if permitted for the fare, will have a $30 service fee charged by Orbitz. Additional airline charges may apply.

Other conditions: Schedules, fares and rules are subject to change without notice. Seats are limited and may not be available on all flights/dates or in all markets. Lower fares may be available. Fares will not be honored retroactively or in exchange for any wholly/partially unused ticket. Tickets are non-transferable and non-refundable. Fare rules are provided for the selected itinerary before booking.