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$78+ 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 8/12. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Aug 5 — Aug 121
Tue 8/5
Tue 8/12
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 July 31, 2025.

Round-trip from

$92
(Mytrip)

One-way from

$78
(FlightHub)

Popular in

December

Cheapest in

November

Average price

$203

Good round-trip deal

$156 or less

Good one-way deal

$96 or less
From Illinois to Colorado
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One-way flight from Illinois to Colorado
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High demand for flights, 0% 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 July 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 July 31, 2025.

This Mytrip deal was found by Cheapflights users on 7/30. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/83:18 pmPIA - DEN
Nonstop2h 16mAllegiant Air
Fri 9/195:24 pmDEN - PIA
Nonstop2h 00mAllegiant Air
Deal found 7/30$92
This Cheapflightsfares deal was found by Cheapflights users on 7/30. 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 8/167:29 pmSTL - DEN
Nonstop2h 29mFrontier
Wed 8/206:00 amDEN - STL
Nonstop2h 11mFrontier
Deal found 7/30$100
This Kiwi.com deal was found by Cheapflights users on 7/29. 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.
Sat 9/138:25 amORD - DEN
Nonstop2h 51mFrontier
Sat 9/135:50 pmDEN - ORD
Nonstop2h 38mFrontier
Deal found 7/29$118
This Cheapflightsfares deal was found by Cheapflights users on 7/29. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/1812:35 pmMDW - DEN
Nonstop2h 44mFrontier
Fri 8/229:00 pmDEN - MDW
Nonstop2h 24mFrontier
Deal found 7/29$122
This Southwest deal was found by Cheapflights users on 7/29. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/78:00 amMDW - DEN
Nonstop2h 45mSouthwest
Tue 10/147:20 pmDEN - MDW
Nonstop2h 20mSouthwest
Deal found 7/29$157
This United Airlines deal was found by Cheapflights users on 7/31. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/49:00 amSTL - DEN
Nonstop2h 20mUnited Airlines
Sat 10/48:45 pmDEN - STL
Nonstop2h 13mUnited Airlines
Deal found 7/31$157
This American Airlines deal was found by Cheapflights users on 7/30. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/139:56 amORD - COS
Nonstop2h 55mAmerican Airlines
Sat 9/2012:21 pmCOS - ORD
Nonstop2h 45mAmerican Airlines
Deal found 7/30$216
This United Airlines deal was found by Cheapflights users on 7/31. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/253:40 pmMLI - DEN
1 stop7h 19mUnited Airlines
Sat 8/305:39 pmDEN - MLI
Nonstop2h 14mUnited Airlines
Deal found 7/31$219
This United Airlines deal was found by Cheapflights users on 7/29. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/309:07 amORD - COS
Nonstop2h 49mUnited Airlines
Tue 9/26:25 pmCOS - ORD
1 stop4h 34mUnited Airlines
Deal found 7/29$227
This American Airlines deal was found by Cheapflights users on 7/31. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/85:11 pmPIA - DEN
1 stop5h 58mAmerican Airlines
Fri 9/192:17 pmDEN - PIA
1 stop6h 19mAmerican Airlines
Deal found 7/31$229
This American Airlines deal was found by Cheapflights users on 7/30. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/114:29 pmMLI - DEN
1 stop7h 40mAmerican Airlines
Wed 10/155:32 pmDEN - MLI
1 stop5h 18mAmerican Airlines
Deal found 7/30$229
This American Airlines deal was found by Cheapflights users on 7/29. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/229:40 amORD - ASE
Nonstop3h 06mAmerican Airlines
Tue 8/2612:03 pmASE - ORD
Nonstop2h 58mAmerican Airlines
Deal found 7/29$229

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 July 31, 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

PeoriaDenver

PIA - DEN

PIADEN

Greater Peoria

Mon 9/8

3:18 pm-4:34 pm

Nonstop2h 16m

Denver Intl

Fri 9/19

5:24 pm-8:24 pm

Nonstop2h 00m

$92

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Sat 8/16

7:29 pm-8:58 pm

Nonstop2h 29m

Denver Intl

Wed 8/20

6:00 am-9:11 am

Nonstop2h 11m

$100

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Sat 9/13

8:25 am-10:16 am

Nonstop2h 51m

Denver Intl

Sat 9/13

5:50 pm-9:28 pm

Nonstop2h 38m

$118

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Mon 8/18

12:35 pm-2:19 pm

Nonstop2h 44m

Denver Intl

Fri 8/22

9:00 pm-12:24 am

Nonstop2h 24m

$122

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Tue 10/7

8:00 am-9:45 am

Nonstop2h 45m

Denver Intl

Tue 10/14

7:20 pm-10:40 pm

Nonstop2h 20m

$157

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Sat 10/4

9:00 am-10:20 am

Nonstop2h 20m

Denver Intl

Sat 10/4

8:45 pm-11:58 pm

Nonstop2h 13m

$157

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Sat 8/23

6:35 pm-8:22 pm

Nonstop2h 47m

Denver Intl

Tue 8/26

7:22 am-10:53 am

Nonstop2h 31m

$161

ChicagoColorado Springs

ORD - COS

ORDCOS

Chicago O'Hare Intl

Sat 9/13

9:56 am-11:51 am

Nonstop2h 55m

Colorado Springs

Sat 9/20

12:21 pm-4:06 pm

Nonstop2h 45m

$216

PeoriaDenver

PIA - DEN

PIADEN

Greater Peoria

Wed 8/20

8:45 am-10:26 am

Nonstop2h 41m

Denver Intl

Tue 8/26

2:45 pm-10:15 pm

1 stop6h 30m

$219

MolineDenver

MLI - DEN

MLIDEN

Moline Quad-City

Mon 8/25

3:40 pm-9:59 pm

1 stop7h 19m

Denver Intl

Sat 8/30

5:39 pm-8:53 pm

Nonstop2h 14m

$219

Flights are sorted by cheapest round-trip flights first.

Deals found on 7/29

Showing 1-10 of 58 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, October is the cheapest month in which you can book a flight from Illinois to Colorado (average of $197). Flying from Illinois to Colorado in March is currently the most expensive (average of $278). 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 July 31, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Illinois to Colorado as you normally would.

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 July 31, 2025.

The most flights from USIL to USCO are scheduled on a Thursday (63 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (28 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 July 31, 2025.
Read reviews from past customers who have flown Alaska Airlines, Southwest, and Delta from Illinois to Colorado. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Entertainment

7.1

Boarding

8.1

Comfort

7.8

Food

7.1

Overall

8.0

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
Alaska Airlines
8.0
Very good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Entertainment

7.1

Boarding

8.1

Comfort

7.8

Food

7.1

Overall

8.0

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
Southwest
8.0
Very good
4,246 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Entertainment

7.1

Boarding

8.1

Comfort

7.8

Food

7.1

Overall

8.0

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
Delta
8.0
Very good
7,981 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Entertainment

7.1

Boarding

8.1

Comfort

7.8

Food

7.1

Overall

8.0

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
United Airlines
7.4
Good
8,900 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Entertainment

7.1

Boarding

8.1

Comfort

7.8

Food

7.1

Overall

8.0

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
American Airlines
7.2
Good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Entertainment

7.1

Boarding

8.1

Comfort

7.8

Food

7.1

Overall

8.0

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.

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.

  • 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 $78 on Frontier. Other airlines that offer cheap prices include United Airlines from $79 and Southwest from $79 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, October is the cheapest month in which you can book a flight from Illinois to Colorado (average of $197). Flying from Illinois to Colorado in March is currently the most expensive (average of $278). 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 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 July 31, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$52Average$163FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$83Average$146FlexibilityNo cancel feeOn-time88%
American AirlinesCheapest$153Average$423FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$157Average$334FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$158Average$474FlexibilityNo cancel feeOn-time69%
DeltaCheapest$228Average$248FlexibilityNo cancel feeOn-timeN/A

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