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$49+ 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 4/20. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Apr 6 — Apr 131
Sun 4/6
Sun 4/13
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 April 1, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$72
(Cheapflightsfares)

One-way from

$49
(Cheapflightsfares)

Popular in

December

Cheapest in

September

Average price

$169

Good round-trip deal

$155 or less

Good one-way deal

$104 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. 5% potential increase in price ($10 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 April 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 April 1, 2025.

This Frontier deal was found by Cheapflights users on 4/1. 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 5/242:44 pmMDW - DEN
Nonstop2h 49mFrontier
Tue 5/275:26 pmDEN - MDW
Nonstop2h 27mFrontier
Deal found 4/1$80
This Frontier deal was found by Cheapflights users on 3/31. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/46:00 amORD - DEN
Nonstop2h 51mFrontier
Wed 6/118:22 pmDEN - ORD
Nonstop2h 37mFrontier
Deal found 3/31$80
This Cheapflightsfares deal was found by Cheapflights users on 4/1. 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 5/38:15 pmSTL - DEN
Nonstop2h 33mFrontier
Sat 5/106:50 amDEN - STL
Nonstop2h 09mFrontier
Deal found 4/1$96
This Booking.com deal was found by Cheapflights users on 3/31. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/23:08 pmPIA - DEN
Nonstop2h 19mAllegiant Air
Fri 5/95:17 pmDEN - PIA
Nonstop2h 00mAllegiant Air
Deal found 3/31$98
This Southwest deal was found by Cheapflights users on 4/1. 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 5/65:50 amMDW - DEN
Nonstop2h 35mSouthwest
Wed 5/77:25 pmDEN - MDW
Nonstop2h 25mSouthwest
Deal found 4/1$151
This United Airlines deal was found by Cheapflights users on 4/1. 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.
Tue 4/229:17 pmORD - DEN
Nonstop2h 55mUnited Airlines
Wed 4/239:05 pmDEN - ORD
Nonstop2h 30mUnited Airlines
Deal found 4/1$151
This American Airlines deal was found by Cheapflights users on 3/31. 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.
Sat 5/38:38 amORD - DEN
Nonstop2h 45mAmerican Airlines
Sat 5/312:31 pmDEN - ORD
Nonstop2h 31mAmerican Airlines
Deal found 3/31$154
This Southwest deal was found by Cheapflights users on 4/1. 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 5/67:00 amORD - DEN
Nonstop2h 40mSouthwest
Wed 5/77:00 amDEN - ORD
1 stop8h 25mSouthwest
Deal found 4/1$161
This CheapOair deal was found by Cheapflights users on 4/1. 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 4/257:35 pmORD - DEN
1 stop23h 07mMultiple Airlines
Mon 4/288:16 pmDEN - ORD
Nonstop2h 22mMultiple Airlines
Deal found 4/1$174
This United Airlines deal was found by Cheapflights users on 4/1. 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.
Tue 4/297:35 pmORD - COS
Nonstop3h 04mUnited Airlines
Tue 5/66:39 pmCOS - ORD
1 stop4h 50mUnited Airlines
Deal found 4/1$196
This Southwest deal was found by Cheapflights users on 3/31. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/291:00 pmSTL - DEN
Nonstop2h 20mSouthwest
Sat 5/36:40 amDEN - STL
Nonstop2h 05mSouthwest
Deal found 3/31$196
This American Airlines deal was found by Cheapflights users on 4/1. 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 5/35:26 amSTL - DEN
1 stop5h 21mAmerican Airlines
Sat 5/103:49 pmDEN - STL
1 stop5h 03mAmerican Airlines
Deal found 4/1$199

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 April 1, 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

Thu 5/1

4:07 pm-5:41 pm

Nonstop2h 34m

Denver Intl

Mon 5/5

6:00 am-9:09 am

Nonstop2h 09m

$72

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Sat 5/24

2:44 pm-4:33 pm

Nonstop2h 49m

Denver Intl

Tue 5/27

5:26 pm-8:53 pm

Nonstop2h 27m

$80

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Wed 6/4

6:00 am-7:51 am

Nonstop2h 51m

Denver Intl

Sat 6/7

8:22 pm-11:59 pm

Nonstop2h 37m

$80

PeoriaDenver

PIA - DEN

PIADEN

Greater Peoria

Fri 5/2

3:08 pm-4:27 pm

Nonstop2h 19m

Denver Intl

Fri 5/9

5:17 pm-8:17 pm

Nonstop2h 00m

$98

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Tue 5/6

5:50 am-7:25 am

Nonstop2h 35m

Denver Intl

Wed 5/7

7:25 pm-10:50 pm

Nonstop2h 25m

$151

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Tue 4/22

9:17 pm-11:12 pm

Nonstop2h 55m

Denver Intl

Wed 4/23

9:05 pm-12:35 am

Nonstop2h 30m

$151

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Sat 5/3

8:38 am-10:23 am

Nonstop2h 45m

Denver Intl

Sat 5/3

12:31 pm-4:02 pm

Nonstop2h 31m

$154

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Tue 5/6

7:00 am-8:40 am

Nonstop2h 40m

Denver Intl

Wed 5/7

7:00 am-4:25 pm

1 stop8h 25m

$161

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Fri 4/25

7:35 pm-5:42 pm

1 stop23h 07m

Denver Intl

Mon 4/28

8:16 pm-11:38 pm

Nonstop2h 22m

$174

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Sat 5/3

5:26 am-9:47 am

1 stop5h 21m

Denver Intl

Sat 5/10

3:49 pm-9:52 pm

1 stop5h 03m

$199

Flights are sorted by cheapest round-trip flights first.

Deals found on 4/1

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, 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 April 1, 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 April 1, 2025.

The most flights from USIL to USCO are scheduled on a Tuesday (48 on average). You will have fewer flight options on Sunday, 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 April 1, 2025.
Peruse reviews from past customers who have flown with Alaska Airlines, Southwest 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.
Alaska Airlines
8.0
Very good
9,820 reviews

Entertainment

7.1

Comfort

7.9

Food

7.1

Overall

8.0

Crew

8.5

Boarding

8.2

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
Alaska Airlines
8.0
Very good
9,820 reviews
Alaska Airlines
8.0
Very good
9,820 reviews

Entertainment

7.1

Comfort

7.9

Food

7.1

Overall

8.0

Crew

8.5

Boarding

8.2

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
Southwest
8.0
Very good
4,277 reviews
Alaska Airlines
8.0
Very good
9,820 reviews

Entertainment

7.1

Comfort

7.9

Food

7.1

Overall

8.0

Crew

8.5

Boarding

8.2

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
Delta
8.0
Very good
7,898 reviews
Alaska Airlines
8.0
Very good
9,820 reviews

Entertainment

7.1

Comfort

7.9

Food

7.1

Overall

8.0

Crew

8.5

Boarding

8.2

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
United Airlines
7.4
Good
8,615 reviews
Alaska Airlines
8.0
Very good
9,820 reviews

Entertainment

7.1

Comfort

7.9

Food

7.1

Overall

8.0

Crew

8.5

Boarding

8.2

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
Allegiant Air
7.3
Good
731 reviews
Alaska Airlines
8.0
Very good
9,820 reviews

Entertainment

7.1

Comfort

7.9

Food

7.1

Overall

8.0

Crew

8.5

Boarding

8.2

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them

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 $49 on Frontier. Other airlines that offer cheap prices include Allegiant Air from $53 and Southwest from $76 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 April 1, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$43Average$152FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$91Average$161FlexibilityNo cancel feeOn-time88%
American AirlinesCheapest$146Average$438FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$152Average$481FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$158Average$330FlexibilityNo cancel feeOn-time63%
DeltaCheapest$217Average$248FlexibilityNo cancel feeOn-timeN/A

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