Frontier's UpFront Plus guarantees an empty middle seat for extra comfort.
Early check-in helps secure your place due to frequent overbooking.

Most accurate provider | CheapOair 3 stars |
|---|---|
Most trusted provider | CheapOair 3 stars |
Round-trip from | $66 (Kiwi.com) |
One-way from | $41 (Kiwi.com) |
Popular in | March |
Cheapest in | October |
Average price | $195 |
Good round-trip deal | $183 or less |
Good one-way deal | $125 or less |
Fly from
Fly to
Route
Depart
Return
Price
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Wed 11/26
9:54 pm-3:58 am
1 stop7h 04m
Denver Intl
Thu 11/27
9:19 am-11:57 pm
1 stop13h 38m
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Wed 12/10
11:40 am-5:52 pm
1 stop7h 12m
Denver Intl
Fri 12/12
12:50 am-10:24 am
1 stop8h 34m
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Mon 1/12
9:59 am-3:36 pm
1 stop6h 37m
Denver Intl
Tue 1/20
12:30 am-8:53 am
1 stop7h 23m
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Mon 3/2
6:48 pm-12:27 am
1 stop6h 39m
Denver Intl
Tue 3/3
12:59 am-9:08 am
1 stop7h 09m
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Mon 1/12
9:59 am-3:36 pm
1 stop6h 37m
Denver Intl
Fri 1/16
5:51 pm-11:25 pm
1 stop4h 34m
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Sat 12/13
5:45 pm-7:05 pm
Nonstop2h 20m
Denver Intl
Mon 12/15
8:15 am-11:20 am
Nonstop2h 05m
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Tue 12/23
10:10 pm-11:33 pm
1 stop26h 23m
Denver Intl
Sat 1/3
6:50 am-10:02 am
Nonstop2h 12m
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Sat 2/14
4:30 pm-6:04 pm
Nonstop2h 34m
Denver Intl
Tue 2/17
5:25 pm-8:26 pm
Nonstop2h 01m
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Wed 12/3
9:30 am-3:10 pm
1 stop6h 40m
Denver Intl
Fri 12/5
12:50 am-10:24 am
1 stop8h 34m
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Sat 1/17
4:15 pm-5:53 pm
Nonstop2h 38m
Denver Intl
Tue 1/20
4:15 pm-10:58 pm
1 stop5h 43m
| Provider | Price Accuracy | Trust Score* |
|---|---|---|
| Price Accuracy2 stars | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*1 star | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*2 stars | |
| Price Accuracy- | Trust Score*1 star | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy- | Trust Score*1 star |
Booking 75 days in advance of your planned departure date is, on average, the best time to get cheap flights from St. Louis to Denver. The general trend is that the closer you book to the departure date, the more expensive your flight will be.
Currently, February is the cheapest month in which you can book a flight from St. Louis to Denver (average of $36). Flying from St. Louis to Denver in July is currently the most expensive (average of $104). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.
It’s optimal to fly from St. Louis to Denver in the evening. By choosing this option you can save up to 62% on the cost of your flight, compared to a flight at noon.
Travelers seeking maximum savings on their St. Louis to Denver flight should consider departing on Saturday evenings when fares are most often at their lowest. Monday at noon flights should be avoided if possible as fares are typically the most expensive at this time.
Crew
Food
Overall
Boarding
Comfort
Entertainment
Reviews
Gina,Jul 2025
LAS - DEN
Crew
Food
Overall
Boarding
Comfort
Entertainment
Reviews
Gina,Jul 2025
LAS - DEN
Crew
Food
Overall
Boarding
Comfort
Entertainment
Reviews
Gina,Jul 2025
LAS - DEN
Crew
Food
Overall
Boarding
Comfort
Entertainment
Reviews
Gina,Jul 2025
LAS - DEN
Crew
Food
Overall
Boarding
Comfort
Entertainment
Reviews
Gina,Jul 2025
LAS - DEN
Crew
Food
Overall
Boarding
Comfort
Entertainment
Reviews
Gina,Jul 2025
LAS - DEN
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$50 | Average$125 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$108 | Average$276 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$155 | Average$316 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$177 | Average$294 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$201 | Average$236 | FlexibilityNo cancel fee | On-time71% |