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$39+ 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 1/12. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Jan 14 — Jan 211
Wed 1/14
Wed 1/21
1 adult, Economy
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Cheap 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 December 15, 2025.

This United Airlines deal was found by Cheapflights users on 12/13. 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.
Thu 12/257:10 amORD - DEN
Nonstop2h 55mUnited Airlines
Thu 1/16:00 amDEN - ORD
Nonstop2h 44mUnited Airlines
Deal found 12/13$157
This Super.com deal was found by Cheapflights users on 12/14. 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.
Mon 12/2210:10 pmSTL - DEN
1 stop6h 48mFrontier
Mon 1/56:50 amDEN - STL
Nonstop2h 12mFrontier
Deal found 12/14$163
This Frontier deal was found by Cheapflights users on 12/13. 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.
Thu 12/185:25 amORD - DEN
1 stop9h 50mFrontier
Wed 12/248:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 12/13$171
This Kiwi.com deal was found by Cheapflights users on 12/13. 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.
Mon 12/222:15 pmORD - DEN
1 stop9h 44mFrontier
Thu 12/258:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 12/13$173
This CheapOair deal was found by Cheapflights users on 12/13. 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.
Tue 12/302:01 pmMDW - DEN
Nonstop2h 45mFrontier
Thu 1/811:59 pmDEN - MDW
1 stop22h 10mFrontier
Deal found 12/13$179
This Kiwi.com deal was found by Cheapflights users on 12/12. 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.
Thu 12/257:00 amORD - DEN
Nonstop2h 56mFrontier
Wed 12/318:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 12/12$182
This Expedia deal was found by Cheapflights users on 12/14. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/2210:10 pmSTL - DEN
1 stop11h 54mFrontier
Mon 12/2910:37 pmDEN - STL
1 stop21h 48mFrontier
Deal found 12/14$183
This Orbitz deal was found by Cheapflights users on 12/13. 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 Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/2010:10 pmSTL - DEN
1 stop11h 54mFrontier
Mon 12/2910:37 pmDEN - STL
1 stop21h 48mFrontier
Deal found 12/13$187
This CheapOair deal was found by Cheapflights users on 12/14. 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.
Wed 12/247:00 amORD - DEN
Nonstop2h 56mFrontier
Wed 12/318:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 12/14$189
This Kiwi.com deal was found by Cheapflights users on 12/14. 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 12/247:00 amORD - DEN
Nonstop2h 56mFrontier
Thu 12/258:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 12/14$190
This Frontier deal was found by Cheapflights users on 12/15. 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.
Wed 12/317:43 pmSTL - DEN
Nonstop2h 32mFrontier
Mon 1/56:50 amDEN - STL
Nonstop2h 12mFrontier
Deal found 12/15$191
This Kiwi.com deal was found by Cheapflights users on 12/12. 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.
Fri 12/267:44 pmORD - DEN
1 stop13h 48mMultiple Airlines
Wed 12/318:45 pmDEN - ORD
Nonstop2h 27mMultiple Airlines
Deal found 12/12$195

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 December 15, 2025.

Most accurate provider

CheapOair
3 stars

Most trusted provider

CheapOair
3 stars

Round-trip from

$73
(Frontier)

One-way from

$39
(Kiwi.com)

Popular in

December

Cheapest in

January

Average price

$273

Good round-trip deal

$178 or less

Good one-way deal

$134 or less
Provider with most accurate pricing for Chicago (CHI)-Denver Intl flight deals.
Search Deals
Provider most trusted by Cheapflights users for Chicago (CHI)-Denver Intl flights.
Search Deals
From Illinois to Colorado
Search Deals
One-way flight from Illinois to Colorado
Search Deals
Highest demand for flights based on searches. 7% potential increase in price ($16 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($6 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
Search Deals
Price to beat on a round-trip flight from Illinois to Colorado.
Search Deals
Price to beat on a one-way flight from Illinois to Colorado.
Search Deals

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 December 15, 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 1/21

6:00 pm-7:38 pm

Nonstop2h 38m

Denver Intl

Sat 1/24

10:10 am-1:16 pm

Nonstop2h 06m

$157

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Sat 1/17

7:40 pm-9:25 pm

Nonstop2h 45m

Denver Intl

Tue 1/20

9:10 am-2:15 pm

1 stop4h 05m

$167

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Wed 1/14

2:36 pm-4:34 pm

Nonstop2h 58m

Denver Intl

Sat 1/17

6:00 am-9:44 am

Nonstop2h 44m

$168

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Mon 2/9

11:20 am-1:05 pm

Nonstop2h 45m

Denver Intl

Sat 2/14

8:25 pm-11:45 pm

Nonstop2h 20m

$176

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Wed 2/18

2:15 pm-9:05 pm

1 stop7h 50m

Denver Intl

Sat 2/21

10:25 am-2:05 pm

Nonstop2h 40m

$178

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Wed 1/28

12:53 pm-2:51 pm

Nonstop2h 58m

Denver Intl

Sat 1/31

6:00 am-9:44 am

Nonstop2h 44m

$179

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Sat 2/7

7:40 pm-9:25 pm

Nonstop2h 45m

Denver Intl

Tue 2/10

9:45 am-1:10 pm

Nonstop2h 25m

$179

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Wed 1/21

8:45 am-10:35 am

Nonstop2h 50m

Denver Intl

Thu 1/22

9:40 am-1:24 pm

Nonstop2h 44m

$187

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Sat 2/21

3:15 pm-4:55 pm

Nonstop2h 40m

Denver Intl

Tue 2/24

9:45 am-1:10 pm

Nonstop2h 25m

$187

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Fri 1/23

8:02 pm-9:59 pm

Nonstop2h 57m

Denver Intl

Sat 2/21

4:15 pm-7:50 pm

Nonstop2h 35m

$188

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/14

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 $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 December 15, 2025.

It’s optimal to fly from Illinois to Colorado in the evening. By choosing this option you can save up to 30% 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 December 15, 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
7.9
Good
4,250 reviews

Comfort

8.0

Crew

8.6

Boarding

8.1

Overall

7.9

Food

7.0

Entertainment

7.5

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Southwest
7.9
Good
4,250 reviews
Southwest
7.9
Good
4,250 reviews

Comfort

8.0

Crew

8.6

Boarding

8.1

Overall

7.9

Food

7.0

Entertainment

7.5

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
United Airlines
7.4
Good
9,093 reviews
Southwest
7.9
Good
4,250 reviews

Comfort

8.0

Crew

8.6

Boarding

8.1

Overall

7.9

Food

7.0

Entertainment

7.5

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
American Airlines
7.2
Good
11,048 reviews
Southwest
7.9
Good
4,250 reviews

Comfort

8.0

Crew

8.6

Boarding

8.1

Overall

7.9

Food

7.0

Entertainment

7.5

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Allegiant Air
7.2
Good
700 reviews
Southwest
7.9
Good
4,250 reviews

Comfort

8.0

Crew

8.6

Boarding

8.1

Overall

7.9

Food

7.0

Entertainment

7.5

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Frontier
5.8
Fair
3,082 reviews
Southwest
7.9
Good
4,250 reviews

Comfort

8.0

Crew

8.6

Boarding

8.1

Overall

7.9

Food

7.0

Entertainment

7.5

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

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 United Airlines, Southwest, and Delta fly from Illinois to Colorado in about 2h 38m. The time it takes to get you to your destination can typically vary by up to 3h 13m. The distance between Illinois and Colorado is about 767 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 $37 on Frontier. Other airlines that offer cheap prices include Allegiant Air from $58 and American Airlines from $71 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 $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.

See more FAQs

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.
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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 December 15, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$58Average$161FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$74Average$147FlexibilityNo cancel feeOn-time88%
American AirlinesCheapest$153Average$401FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$155Average$436FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$157Average$303FlexibilityNo cancel feeOn-time63%

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