$40 Cheap flight deals from St. Louis (STL) to Boulder (DEN)

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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, May 3 - Wed, May 7
STL
Lambert-St. Louis Intl.
DEN
Denver Intl.
$136 Roundtrip, found 12 hours ago
$136
Roundtrip
found 12 hours ago
Select Frontier Airlines flight, departing Sat, May 3 from Lambert-St. Louis Intl. to Denver Intl., returning Wed, May 7, priced at $136 found 12 hours ago

Airfares from $40 One Way, $79 Round Trip from St. Louis to Boulder

Prices starting at $79 for return flights and $40 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.

Wed, May 7 - Sat, May 10
STL
St. Louis
DEN
Denver
$79 Roundtrip, just found
$79
Roundtrip
just found
Select Frontier Airlines flight, departing Wed, May 7 from St. Louis to Denver, returning Sat, May 10, priced at $79 just found
Wed, May 14 - Wed, May 21
STL
St. Louis
DEN
Denver
$105 Roundtrip, found 6 hours ago
$105
Roundtrip
found 6 hours ago
Select Frontier Airlines flight, departing Wed, May 14 from St. Louis to Denver, returning Wed, May 21, priced at $105 found 6 hours ago
Sat, May 24 - Wed, May 28
STL
St. Louis
DEN
Denver
$110 Roundtrip, just found
$110
Roundtrip
just found
Select Frontier Airlines flight, departing Sat, May 24 from St. Louis to Denver, returning Wed, May 28, priced at $110 just found
Wed, May 14 - Fri, May 16
STL
St. Louis
DEN
Denver
$115 Roundtrip, found 1 day ago
$115
Roundtrip
found 1 day ago
Select Frontier Airlines flight, departing Wed, May 14 from St. Louis to Denver, returning Fri, May 16, priced at $115 found 1 day ago
Wed, May 14 - Mon, May 19
STL
St. Louis
DEN
Denver
$115 Roundtrip, found 14 hours ago
$115
Roundtrip
found 14 hours ago
Select Frontier Airlines flight, departing Wed, May 14 from St. Louis to Denver, returning Mon, May 19, priced at $115 found 14 hours ago

Boulder economy flight packages

Price found within the past 48 hours. Click for updated prices.
Super 8 by Wyndham Henderson North East Denver
2.0-star property

Super 8 by Wyndham Henderson North East Denver

7.4/10 Good! (1,004 reviews)

Jun 19 - Jun 23

4 night stay

St. Louis (STL) to Denver (DEN)

United • Coach

Denver (DEN) to St. Louis (STL)

Frontier Airlines • Coach
per person
found 1 day ago
Good personal , Clean and complimentary breakfast perfect

Reviewed on Oct 7, 2024

Days Inn by Wyndham Thornton
2.5-star property

Days Inn by Wyndham Thornton

7/10 Good! (67 reviews)

Jun 19 - Jun 23

4 night stay

St. Louis (STL) to Denver (DEN)

United • Coach

Denver (DEN) to St. Louis (STL)

Frontier Airlines • Coach
per person
found 1 day ago
The first room I was assigned had no pillows for the bed and when attempting to call the front desk, the phone did not work... the second room had a cracked window, which looked like it might fall out, the television didn't work, the bed sagged in the middle, and the toilet seat was cracked through at the back...

Reviewed on Apr 11, 2025

La Quinta Inn by Wyndham Denver Northglenn
2.5-star property

La Quinta Inn by Wyndham Denver Northglenn

6.4/10 (1,005 reviews)

Jun 19 - Jun 23

4 night stay

St. Louis (STL) to Denver (DEN)

United • Coach

Denver (DEN) to St. Louis (STL)

Frontier Airlines • Coach
per person
found 1 day ago
Bed was very comfortable and close to where we needed to go. Shower had great pressure, but not really warm (going to take a look at it). Parking lot needs some work, but at least you didn't have to worry about speeders, lol. Staff was very accommodating and friendly! Great place!

Reviewed on Jun 26, 2023

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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
12:59PM UTC
Latest Flight Arrival
2:15AM UTC

St. Louis to Boulder

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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.