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$42+ 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 12/20. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Nov 29 — Dec 61
Sat 11/29
Sat 12/6
1 adult, Economy
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Cheap flight deals from Illinois to Colorado

Keep the following information in mind while searching for Illinois to Colorado flight deals. Data was last updated October 30, 2025.

Most accurate provider

CheapOair
3 stars

Most trusted provider

CheapOair
3 stars

Round-trip from

$70
(Mytrip)

One-way from

$42
(Priceline)

Popular in

December

Cheapest in

November

Average price

$200

Good round-trip deal

$143 or less

Good one-way deal

$106 or less
Provider with most accurate pricing for Chicago (CHI)-Denver Intl flight deals.
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Provider most trusted by Cheapflights users for Chicago (CHI)-Denver Intl flights.
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From Illinois to Colorado
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One-way flight from Illinois to Colorado
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High demand for flights, 3% potential price rise
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Cheapest flight prices on average. 2% potential price decrease ($4 potential savings vs. average RT price).
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Average for round-trip flights in October 2025
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Price to beat on a round-trip flight from Illinois to Colorado.
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Price to beat on a one-way flight from Illinois to Colorado.
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Find flight deals from Illinois to Colorado

Cheapest flights from Illinois to Colorado
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 October 30, 2025.

This Mytrip deal was found by Cheapflights users on 10/28. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/137:43 pmSTL - DEN
Nonstop2h 32mFrontier
Sat 12/206:50 amDEN - STL
Nonstop2h 12mFrontier
Deal found 10/28$70
This Frontier deal was found by Cheapflights users on 10/30. 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 12/812:07 pmSTL - DEN
1 stop13h 13mFrontier
Sat 12/137:05 amDEN - STL
Nonstop2h 09mFrontier
Deal found 10/30$82
This Flightnetwork deal was found by Cheapflights users on 10/29. 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 Flightnetwork is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/67:43 pmSTL - DEN
Nonstop2h 32mFrontier
Mon 12/811:59 pmDEN - STL
1 stop21h 34mFrontier
Deal found 10/29$83
This Cheapflightsfares deal was found by Cheapflights users on 10/30. 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 11/154:51 pmSTL - DEN
1 stop12h 08mFrontier
Tue 11/186:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 10/30$86
This Frontier deal was found by Cheapflights users on 10/29. 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 12/137:43 pmSTL - DEN
Nonstop2h 32mFrontier
Sat 1/36:50 amDEN - STL
Nonstop2h 12mFrontier
Deal found 10/29$87
This Frontier deal was found by Cheapflights users on 10/30. 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 12/87:43 pmSTL - DEN
Nonstop2h 32mFrontier
Wed 12/107:05 amDEN - STL
Nonstop2h 09mFrontier
Deal found 10/30$88
This Frontier deal was found by Cheapflights users on 10/30. 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 12/137:43 pmSTL - DEN
Nonstop2h 32mFrontier
Sat 12/1312:59 amDEN - STL
1 stop7h 48mFrontier
Deal found 10/30$91
This Priceline deal was found by Cheapflights users on 10/29. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 11/187:45 pmSTL - DEN
Nonstop2h 28mFrontier
Wed 11/196:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 10/29$92
This Cheapflightsfares deal was found by Cheapflights users on 10/28. 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.
Tue 11/116:05 pmORD - DEN
Nonstop2h 54mFrontier
Mon 11/1712:59 amDEN - ORD
1 stop9h 15mFrontier
Deal found 10/28$94
This Kiwi.com deal was found by Cheapflights users on 10/29. 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 11/126:05 pmORD - DEN
Nonstop2h 54mFrontier
Sat 11/157:59 pmDEN - ORD
Nonstop2h 30mFrontier
Deal found 10/29$95
This CheapOair deal was found by Cheapflights users on 10/30. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/56:00 amORD - DEN
1 stop15h 25mFrontier
Mon 12/88:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 10/30$96
This CheapOair deal was found by Cheapflights users on 10/30. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/58:42 pmMDW - DEN
1 stop13h 20mFrontier
Mon 12/87:45 amDEN - MDW
Nonstop2h 23mFrontier
Deal found 10/30$96

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 October 30, 2025.
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

Wed 12/10

3:30 pm-11:04 pm

1 stop8h 34m

Denver Intl

Sat 12/13

7:05 am-10:14 am

Nonstop2h 09m

$82

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Thu 11/13

7:45 pm-9:13 pm

Nonstop2h 28m

Denver Intl

Mon 11/17

11:03 am-8:12 pm

1 stop8h 09m

$125

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 1/21

5:11 pm-7:45 am

2 stops15h 34m

Denver Intl

Fri 1/23

6:50 am-10:02 am

Nonstop2h 12m

$140

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Thu 12/11

12:04 pm-9:38 pm

1 stop10h 34m

Denver Intl

Sun 12/14

10:44 pm-11:22 am

1 stop11h 38m

$144

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 3/4

7:43 pm-9:15 pm

Nonstop2h 32m

Denver Intl

Mon 3/9

6:50 am-10:02 am

Nonstop2h 12m

$146

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 2/18

5:44 pm-9:04 am

1 stop16h 20m

Denver Intl

Sun 2/22

1:00 pm-4:49 pm

1 stop26h 49m

$154

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Thu 1/8

6:00 am-7:50 am

Nonstop2h 50m

Denver Intl

Sun 1/11

5:25 am-8:55 am

Nonstop2h 30m

$155

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Fri 11/14

11:05 am-11:16 pm

1 stop13h 11m

Denver Intl

Sun 11/16

12:16 am-1:17 pm

1 stop12h 01m

$171

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Tue 1/13

6:00 am-7:50 am

Nonstop2h 50m

Denver Intl

Tue 1/20

1:25 pm-4:45 pm

Nonstop2h 20m

$176

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Sat 1/10

5:10 am-7:00 am

Nonstop2h 50m

Denver Intl

Wed 1/14

9:45 am-1:10 pm

Nonstop2h 25m

$176

Flights are sorted by cheapest round-trip flights first.

Deals found on 10/28

Showing 1-10 of 60 results
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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 $114). 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 October 30, 2025.

It’s optimal to fly from Illinois to Colorado in the evening. By choosing this option you can save up to 27% 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 December 16, 2024.

Travelers seeking maximum savings on their Illinois to Colorado flight should consider departing on Friday 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.

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 October 30, 2025.
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.
Southwest
8.0
Very good
4,243 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Overall

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Southwest
8.0
Very good
4,243 reviews
Southwest
8.0
Very good
4,243 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Overall

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
United Airlines
7.4
Good
8,996 reviews
Southwest
8.0
Very good
4,243 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Overall

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
American Airlines
7.2
Good
11,034 reviews
Southwest
8.0
Very good
4,243 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Overall

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Allegiant Air
7.2
Good
694 reviews
Southwest
8.0
Very good
4,243 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Overall

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Frontier
5.8
Fair
3,123 reviews
Southwest
8.0
Very good
4,243 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Overall

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.

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.

  • How long is the flight from Illinois to Colorado?

    Airlines like Frontier, Southwest, and Delta fly from Illinois to Colorado in about 2h 50m. The time it takes to get you to your destination can typically vary by up to 5h 44m. The distance between Illinois and Colorado is about 893 mi. Both multi-stop and nonstop flights can be found to your destination and back.

  • What are the cheapest airlines to fly from Illinois to Colorado one-way?

    One-way options have recently been found by users for as low as $59 on Frontier. Other airlines that offer cheap prices include Allegiant Air from $66 and Southwest from $78 one-way.

  • Can I find deals for flights from Illinois to Colorado that include hotel bookings?

    Yes. In addition to deals on Illinois to Colorado flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Illinois to Colorado?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Illinois to Colorado.

  • Can I find deals for business class flights from Illinois to Colorado?

    Yes. Cheapflights offers flight deals from Illinois to Colorado by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • 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 $114). 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.

See more FAQs

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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.
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Top 5 airlines flying from Illinois to Colorado

Discover the top 5 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 October 30, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$59Average$159FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$76Average$140FlexibilityNo cancel feeOn-time88%
American AirlinesCheapest$152Average$411FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$157Average$317FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$160Average$454FlexibilityNo cancel feeOn-time69%

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