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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 2/28. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Feb 25 — Mar 41
Tue 2/25
Tue 3/4
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 February 20, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$64
(Kiwi.com)

One-way from

$40
(Frontier)

Popular in

December

Cheapest in

May

Average price

$191

Good round-trip deal

$130 or less

Good one-way deal

$80 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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Highest demand for flights based on searches. 7% potential increase in price ($15 potential increase over avg. RT price).
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Cheapest flight prices on average. 2% potential price decrease ($5 potential savings vs. average RT price).
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Average for round-trip flights in February 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 February 20, 2025.

This Kiwi.com deal was found by Cheapflights users on 2/20. 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 4/26:51 pmSTL - DEN
Nonstop2h 31mFrontier
Sat 4/56:00 amDEN - STL
Nonstop2h 06mFrontier
Deal found 2/20$64
This FlightHub deal was found by Cheapflights users on 2/20. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 3/66:40 amMDW - DEN
Nonstop2h 52mFrontier
Mon 3/108:55 pmDEN - MDW
Nonstop2h 22mFrontier
Deal found 2/20$71
This Frontier deal was found by Cheapflights users on 2/20. 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 3/76:30 amORD - DEN
Nonstop3h 03mFrontier
Mon 3/109:08 pmDEN - ORD
Nonstop2h 36mFrontier
Deal found 2/20$73
This Cheapflightsfares deal was found by Cheapflights users on 2/20. 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 3/33:11 pmPIA - DEN
Nonstop2h 28mAllegiant Air
Fri 3/75:32 pmDEN - PIA
Nonstop2h 05mAllegiant Air
Deal found 2/20$92
This Mytrip deal was found by Cheapflights users on 2/19. 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 3/3112:10 pmORD - DEN
1 stop7h 43mMultiple Airlines
Wed 4/29:08 pmDEN - ORD
Nonstop2h 34mMultiple Airlines
Deal found 2/19$144
This American Airlines deal was found by Cheapflights users on 2/20. 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.
Tue 4/18:40 pmORD - DEN
Nonstop2h 53mAmerican Airlines
Wed 4/95:26 pmDEN - ORD
Nonstop2h 34mAmerican Airlines
Deal found 2/20$159
This Southwest deal was found by Cheapflights users on 2/19. 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.
Wed 3/2610:05 amMDW - DEN
1 stop4h 25mSouthwest
Wed 4/27:45 pmDEN - MDW
Nonstop2h 20mSouthwest
Deal found 2/19$170
This Southwest deal was found by Cheapflights users on 2/20. 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.
Mon 3/107:10 pmORD - DEN
Nonstop2h 50mSouthwest
Tue 3/185:55 amDEN - ORD
1 stop5h 50mSouthwest
Deal found 2/20$179
This CheapOair deal was found by Cheapflights users on 2/20. 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.
Mon 3/37:04 pmSTL - DEN
Nonstop2h 28mMultiple Airlines
Fri 3/76:50 pmDEN - STL
1 stop15h 44mMultiple Airlines
Deal found 2/20$208
This United Airlines deal was found by Cheapflights users on 2/19. 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 4/58:55 amMLI - DEN
Nonstop2h 35mUnited Airlines
Tue 4/85:50 pmDEN - MLI
Nonstop2h 13mUnited Airlines
Deal found 2/19$209
This Delta deal was found by Cheapflights users on 2/19. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/110:25 amORD - DEN
1 stop7h 51mDelta
Fri 4/412:55 amDEN - ORD
1 stop7h 17mDelta
Deal found 2/19$217
This Delta deal was found by Cheapflights users on 2/20. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/11:16 pmMDW - DEN
1 stop7h 42mDelta
Wed 4/166:20 amDEN - MDW
1 stop5h 15mDelta
Deal found 2/20$217

Find flights from Illinois to Colorado within your budget

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 February 20, 2025.

Fly from

Illinois

Fly to

Colorado

Route

Depart

Return

Price

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 4/2

6:51 pm-8:22 pm

Nonstop2h 31m

Denver Intl

Sat 4/5

6:00 am-9:06 am

Nonstop2h 06m

$64

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Thu 3/6

6:40 am-8:32 am

Nonstop2h 52m

Denver Intl

Mon 3/10

8:55 pm-12:17 am

Nonstop2h 22m

$71

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Fri 3/7

6:30 am-8:33 am

Nonstop3h 03m

Denver Intl

Mon 3/10

9:08 pm-12:44 am

Nonstop2h 36m

$73

PeoriaDenver

PIA - DEN

PIADEN

Greater Peoria

Mon 3/3

3:11 pm-4:39 pm

Nonstop2h 28m

Denver Intl

Fri 3/7

5:32 pm-8:37 pm

Nonstop2h 05m

$92

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Mon 3/31

12:10 pm-6:53 pm

1 stop7h 43m

Denver Intl

Wed 4/2

9:08 pm-12:42 am

Nonstop2h 34m

$144

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Tue 4/1

8:40 pm-10:33 pm

Nonstop2h 53m

Denver Intl

Wed 4/9

5:26 pm-9:00 pm

Nonstop2h 34m

$159

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Wed 3/26

10:05 am-1:30 pm

1 stop4h 25m

Denver Intl

Wed 4/2

7:45 pm-11:05 pm

Nonstop2h 20m

$170

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Mon 3/10

7:10 pm-9:00 pm

Nonstop2h 50m

Denver Intl

Tue 3/18

5:55 am-12:45 pm

1 stop5h 50m

$179

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Mon 3/3

7:04 pm-8:32 pm

Nonstop2h 28m

Denver Intl

Fri 3/7

6:50 pm-11:34 am

1 stop15h 44m

$208

MolineDenver

MLI - DEN

MLIDEN

Moline Quad-City

Sat 4/5

8:55 am-10:30 am

Nonstop2h 35m

Denver Intl

Tue 4/8

5:50 pm-9:03 pm

Nonstop2h 13m

$209

Flights are sorted by cheapest round-trip flights first.

Deals found on 2/20

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.

Travel insights for flights from Illinois to Colorado

Get recent, data-driven insights about flights from Illinois to Colorado including ideal travel times, pricing trends, and more.

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 February 20, 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 February 20, 2025.

The most flights from USIL to USCO are scheduled on a Thursday (47 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (17 on average).

Rainfall in Colorado by month

Plan your trip to Colorado by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Colorado ranges from 0.5 - 2.3 inches per month. May is typically the wettest month, when rainfall can reach 2.3 in. January is typically the driest time to visit Colorado when rainfall is around 0.5 in.

Temperature in Colorado by month

Plan your trip to Colorado by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Colorado, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 73.4 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 30.2 F).

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 February 20, 2025.
Peruse reviews from past customers who have flown with Southwest, Alaska Airlines and Delta from Illinois to Colorado to help guide your decision. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.1
Very good
4,411 reviews

Food

7.1

Comfort

8.1

Crew

8.7

Overall

8.1

Entertainment

7.6

Boarding

8.2

Reviews

1 / 20

2.0
Mediocre

Steven,Feb 2025

BZN - DEN

Bozeman Airport knows how to deal with snow. I saw many airlines leave with only small delays due to the foot of snow. Our plane was 4 hours delayed. I missed my connection in Denver with a 3.5 hour layover. Because of that, the best you Southwest could do was make me wait more hours, them send me to Chicago Midway, where I had to wait overnight, for 7 more hours until a flight to RSW was available. Nobody at Southwest told me that Midway shuts down after 8pm. Everything was closed. I had no idea. You just dumped me there. I am a 65 year old man and you dumped me in Midway without even a couch to lie on. I was awake 21 hours because of this. No, it was not an act of God. Other airlines were moving passengers out. It was incompetence Shame on you.

Southwest
8.1
Very good
4,411 reviews
Southwest
8.1
Very good
4,411 reviews

Food

7.1

Comfort

8.1

Crew

8.7

Overall

8.1

Entertainment

7.6

Boarding

8.2

Reviews

1 / 20

2.0
Mediocre

Steven,Feb 2025

BZN - DEN

Bozeman Airport knows how to deal with snow. I saw many airlines leave with only small delays due to the foot of snow. Our plane was 4 hours delayed. I missed my connection in Denver with a 3.5 hour layover. Because of that, the best you Southwest could do was make me wait more hours, them send me to Chicago Midway, where I had to wait overnight, for 7 more hours until a flight to RSW was available. Nobody at Southwest told me that Midway shuts down after 8pm. Everything was closed. I had no idea. You just dumped me there. I am a 65 year old man and you dumped me in Midway without even a couch to lie on. I was awake 21 hours because of this. No, it was not an act of God. Other airlines were moving passengers out. It was incompetence Shame on you.

Alaska Airlines
8.0
Very good
9,692 reviews
Southwest
8.1
Very good
4,411 reviews

Food

7.1

Comfort

8.1

Crew

8.7

Overall

8.1

Entertainment

7.6

Boarding

8.2

Reviews

1 / 20

2.0
Mediocre

Steven,Feb 2025

BZN - DEN

Bozeman Airport knows how to deal with snow. I saw many airlines leave with only small delays due to the foot of snow. Our plane was 4 hours delayed. I missed my connection in Denver with a 3.5 hour layover. Because of that, the best you Southwest could do was make me wait more hours, them send me to Chicago Midway, where I had to wait overnight, for 7 more hours until a flight to RSW was available. Nobody at Southwest told me that Midway shuts down after 8pm. Everything was closed. I had no idea. You just dumped me there. I am a 65 year old man and you dumped me in Midway without even a couch to lie on. I was awake 21 hours because of this. No, it was not an act of God. Other airlines were moving passengers out. It was incompetence Shame on you.

Delta
8.0
Very good
8,220 reviews
Southwest
8.1
Very good
4,411 reviews

Food

7.1

Comfort

8.1

Crew

8.7

Overall

8.1

Entertainment

7.6

Boarding

8.2

Reviews

1 / 20

2.0
Mediocre

Steven,Feb 2025

BZN - DEN

Bozeman Airport knows how to deal with snow. I saw many airlines leave with only small delays due to the foot of snow. Our plane was 4 hours delayed. I missed my connection in Denver with a 3.5 hour layover. Because of that, the best you Southwest could do was make me wait more hours, them send me to Chicago Midway, where I had to wait overnight, for 7 more hours until a flight to RSW was available. Nobody at Southwest told me that Midway shuts down after 8pm. Everything was closed. I had no idea. You just dumped me there. I am a 65 year old man and you dumped me in Midway without even a couch to lie on. I was awake 21 hours because of this. No, it was not an act of God. Other airlines were moving passengers out. It was incompetence Shame on you.

United Airlines
7.4
Good
8,766 reviews
Southwest
8.1
Very good
4,411 reviews

Food

7.1

Comfort

8.1

Crew

8.7

Overall

8.1

Entertainment

7.6

Boarding

8.2

Reviews

1 / 20

2.0
Mediocre

Steven,Feb 2025

BZN - DEN

Bozeman Airport knows how to deal with snow. I saw many airlines leave with only small delays due to the foot of snow. Our plane was 4 hours delayed. I missed my connection in Denver with a 3.5 hour layover. Because of that, the best you Southwest could do was make me wait more hours, them send me to Chicago Midway, where I had to wait overnight, for 7 more hours until a flight to RSW was available. Nobody at Southwest told me that Midway shuts down after 8pm. Everything was closed. I had no idea. You just dumped me there. I am a 65 year old man and you dumped me in Midway without even a couch to lie on. I was awake 21 hours because of this. No, it was not an act of God. Other airlines were moving passengers out. It was incompetence Shame on you.

Allegiant Air
7.3
Good
765 reviews
Southwest
8.1
Very good
4,411 reviews

Food

7.1

Comfort

8.1

Crew

8.7

Overall

8.1

Entertainment

7.6

Boarding

8.2

Reviews

1 / 20

2.0
Mediocre

Steven,Feb 2025

BZN - DEN

Bozeman Airport knows how to deal with snow. I saw many airlines leave with only small delays due to the foot of snow. Our plane was 4 hours delayed. I missed my connection in Denver with a 3.5 hour layover. Because of that, the best you Southwest could do was make me wait more hours, them send me to Chicago Midway, where I had to wait overnight, for 7 more hours until a flight to RSW was available. Nobody at Southwest told me that Midway shuts down after 8pm. Everything was closed. I had no idea. You just dumped me there. I am a 65 year old man and you dumped me in Midway without even a couch to lie on. I was awake 21 hours because of this. No, it was not an act of God. Other airlines were moving passengers out. It was incompetence Shame on you.

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 $40 on Frontier. Other airlines that offer cheap prices include Allegiant Air from $53 and United Airlines from $80 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 February 20, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$41Average$150FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$92Average$167FlexibilityNo cancel feeOn-time88%
American AirlinesCheapest$140Average$430FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$150Average$482FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$157Average$329FlexibilityNo cancel feeOn-time63%
DeltaCheapest$185Average$258FlexibilityNo cancel feeOn-timeN/A
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