$23+ Cheap flights from Illinois to Colorado
This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 2/28. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Feb 27 — Mar 61
1 adult, Economy
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Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.Cheap flight deals from Illinois to Colorado
Cheapest flights from Illinois to ColoradoExplore the most affordable flight options available from Illinois to Colorado. Find the lowest fares from popular airlines and budget airlines, with prices last updated on January 28, 2026.
Explore the most affordable flight options available from Illinois to Colorado. Find the lowest fares from popular airlines and budget airlines, with prices last updated on January 28, 2026.
This Kiwi.com deal was found by Cheapflights users on 1/26. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 2/73:46 pm
STL
- DEN
Nonstop2h 37m
Frontier
Wed 2/1110:50 am
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 1/26![Frontier logo]()
$67
This Kiwi.com deal was found by Cheapflights users on 1/26. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 2/254:51 pm
STL
- DEN
Nonstop2h 34m
Frontier
Sat 2/2810:48 am
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 1/26![Frontier logo]()
$71
This Cheapflightsfares deal was found by Cheapflights users on 1/26. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 2/212:51 pm
STL
- DEN
Nonstop2h 27m
Frontier
Wed 2/2512:48 pm
DEN
- STL
Nonstop2h 05m
Frontier
Deal found 1/26![Frontier logo]()
$72
This Super.com deal was found by Cheapflights users on 1/25. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 2/142:51 pm
STL
- DEN
Nonstop2h 27m
Frontier
Wed 2/1812:48 pm
DEN
- STL
Nonstop2h 05m
Frontier
Deal found 1/25![Frontier logo]()
$76
This deal was found by Cheapflights users on 1/25. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 2/282:51 pm
STL
- DEN
Nonstop2h 27m
Frontier
Sat 3/76:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Deal found 1/25![Frontier logo]()
$85
This Kiwi.com deal was found by Cheapflights users on 1/25. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 2/812:03 pm
STL
- DEN
Nonstop2h 33m
Frontier
Wed 2/1110:50 am
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 1/25![Frontier logo]()
$87
This Frontier deal was found by Cheapflights users on 1/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 3/168:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Mon 3/236:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Deal found 1/27![Frontier logo]()
$89
This Kiwi.com deal was found by Cheapflights users on 1/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 2/812:03 pm
STL
- DEN
Nonstop2h 33m
Frontier
Fri 2/1310:01 am
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 1/27![Frontier logo]()
$93
This Frontier deal was found by Cheapflights users on 1/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 3/288:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Sat 4/46:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 1/27![Frontier logo]()
$94
This Super.com deal was found by Cheapflights users on 1/26. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 2/43:46 pm
STL
- DEN
Nonstop2h 37m
Frontier
Mon 2/99:41 am
DEN
- STL
Nonstop2h 09m
Frontier
Deal found 1/26![Frontier logo]()
$97
This Frontier deal was found by Cheapflights users on 1/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 2/272:35 pm
ORD
- DEN
Nonstop3h 09m
Frontier
Mon 3/26:00 am
DEN
- ORD
1 stop14h 34m
Frontier
Deal found 1/27![Frontier logo]()
$118
This Cheapflightsfares deal was found by Cheapflights users on 1/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/45:53 pm
ORD
- DEN
Nonstop3h 08m
Frontier
Sat 4/119:00 pm
DEN
- ORD
Nonstop2h 38m
Frontier
Deal found 1/27![Frontier logo]()
$119
Find flight deals from Illinois to Colorado
Keep the following information in mind while searching for Illinois to Colorado flight deals. Data was last updated January 28, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $67 (Kiwi.com) |
One-way from | $23 (Expedia) |
Popular in | December |
Cheapest in | October |
Average price | $219 |
Good round-trip deal | $199 or less |
Good one-way deal | $137 or less |
Cheapflights Fare Finder
Customize your flight search to find flights from Illinois to Colorado that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated January 28, 2026.
Use the filters below to find and compare flights from Illinois to Colorado that are best for you.
Fly from
Illinois
Fly to
Colorado
Route
Depart
Return
Price
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Thu 3/5
10:11 pm-3:56 am
1 stop6h 45m
Denver Intl
Tue 3/10
11:59 pm-10:37 am
1 stop9h 38m
$166
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Sat 3/7
8:12 pm-9:49 pm
Nonstop2h 37m
Denver Intl
Wed 3/11
10:40 pm-10:02 pm
1 stop22h 22m
$184
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Sat 4/25
10:10 am-2:10 pm
1 stop5h 00m
Denver Intl
Mon 4/27
6:35 am-9:55 am
Nonstop2h 20m
$185
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Wed 3/4
7:10 am-9:03 am
Nonstop2h 53m
Denver Intl
Mon 3/9
7:25 pm-10:54 pm
Nonstop2h 29m
$185
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Thu 4/2
2:35 pm-4:29 pm
Nonstop2h 54m
Denver Intl
Tue 4/7
4:21 pm-8:00 pm
Nonstop2h 39m
$185
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Tue 2/24
5:35 pm-7:20 pm
Nonstop2h 45m
Denver Intl
Wed 2/25
12:05 pm-3:25 pm
Nonstop2h 20m
$187
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Thu 4/9
9:35 pm-11:15 pm
Nonstop2h 40m
Denver Intl
Mon 4/13
8:20 pm-11:40 pm
Nonstop2h 20m
$191
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Thu 4/23
9:49 pm-11:44 pm
Nonstop2h 55m
Denver Intl
Mon 4/27
8:52 pm-12:29 am
Nonstop2h 37m
$191
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Thu 3/12
12:50 pm-2:48 pm
Nonstop2h 58m
Denver Intl
Thu 3/19
8:23 pm-11:52 pm
Nonstop2h 29m
$191
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Thu 2/26
3:45 pm-5:35 pm
Nonstop2h 50m
Denver Intl
Sat 2/28
10:25 am-2:05 pm
Nonstop2h 40m
$193
Showing 1-10 of 60 results
Best time to book a flight from Illinois to Colorado
Have a flexible travel schedule? Discover the best time to fly to Colorado from Illinois with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.
Cheapflights Insights
Everything you need to know about your flight from Illinois to Colorado
What is the cheapest month to book a flight from Illinois to Colorado?
Currently, September is the cheapest month in which you can book a flight from Illinois to Colorado (average of $49). Flying from Illinois to Colorado in July is currently the most expensive (average of $115). 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.
What is the cheapest time of day to fly from IL to CO?
Find hourly flight availability from Illinois to Colorado. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated January 28, 2026.
It’s optimal to fly from Illinois to Colorado at noon. By choosing this option you can save up to 14% on the cost of your flight, compared to a flight in the morning.
What is the cheapest day to fly from Illinois to Colorado?
Use this chart to determine the cheapest time to fly round-trip from Illinois to Colorado. Price data was last updated on March 30, 2025.
Travelers seeking maximum savings on their Illinois to Colorado flight should consider departing on Saturday afternoons when fares are most often at their lowest. Sunday mornings flights should be avoided if possible as fares are typically the most expensive at this time.
Weekly flight availability from Illinois to Colorado
Explore weekly flight availability from Illinois to Colorado. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated January 28, 2026.
The most flights from USIL to USCO are scheduled on a Monday (44 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (24 on average).
Reviews of airlines servicing Colorado
Get insights into the airlines that provide service to Colorado. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Colorado. Reviews last updated January 28, 2026.
Read reviews from past customers who have flown Southwest, United Airlines, and American Airlines from Illinois to Colorado. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Boarding
8.1
Comfort
8.0
Entertainment
7.5
Overall
8.0
Crew
8.6
Food
7.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Boarding
8.1
Comfort
8.0
Entertainment
7.5
Overall
8.0
Crew
8.6
Food
7.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Boarding
8.1
Comfort
8.0
Entertainment
7.5
Overall
8.0
Crew
8.6
Food
7.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Boarding
8.1
Comfort
8.0
Entertainment
7.5
Overall
8.0
Crew
8.6
Food
7.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Boarding
8.1
Comfort
8.0
Entertainment
7.5
Overall
8.0
Crew
8.6
Food
7.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Boarding
8.1
Comfort
8.0
Entertainment
7.5
Overall
8.0
Crew
8.6
Food
7.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Related info for your journey
Find useful and relevant information for your journey from Illinois to Colorado. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.
Browse thousands of different options on Cheapflights for your next trip
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Alternative routes for Illinois to Colorado
See prices for flight routes from nearby airports that may be better suited for you.
Top 6 airlines flying from Illinois to Colorado
Discover the top 6 airlines that operate flights from Illinois to Colorado. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated January 28, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$56 | Average$144 | FlexibilityNo cancel fee | On-time88% | |
| Cheapest$58 | Average$162 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$145 | Average$189 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$154 | Average$404 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$155 | Average$415 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$157 | Average$298 | FlexibilityNo cancel fee | On-time63% |