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$48+ Cheap flights from Colorado to Illinois

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 4/30. Fares are subject to change and may not be available on all flights or dates of travel.
DEN — ORD
Apr 5 — Apr 121
Sat 4/5
Sat 4/12
1 adult, Economy
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Cheap flight deals from Colorado to Illinois

Keep the following information in mind while searching for Colorado to Illinois flight deals. Data was last updated March 31, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$92
(Booking.com)

One-way from

$48
(Kiwi.com)

Popular in

March

Cheapest in

September

Average price

$219

Good round-trip deal

$136 or less

Good one-way deal

$79 or less
Provider with most accurate pricing for Denver Intl-Chicago (CHI) flight deals.
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Provider most trusted by Cheapflights users for Denver Intl-Chicago (CHI) flights.
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From Colorado to Illinois
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One-way flight from Colorado to Illinois
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Highest demand for flights based on searches. 5% potential increase in price ($11 potential increase over avg. RT price).
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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 March 2025
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Price to beat on a round-trip flight from Colorado to Illinois.
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Price to beat on a one-way flight from Colorado to Illinois.
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Find flight deals from Colorado to Illinois

Cheapest flights from Colorado to Illinois
Explore the most affordable flight options available from Colorado to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on March 31, 2025.

This Booking.com deal was found by Cheapflights users on 3/30. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/25:17 pmDEN - PIA
Nonstop2h 00mAllegiant Air
Fri 5/93:08 pmPIA - DEN
Nonstop2h 19mAllegiant Air
Deal found 3/30$92
This CheapOair 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/198:55 pmDEN - MDW
Nonstop2h 26mFrontier
Tue 4/226:45 amMDW - DEN
Nonstop2h 50mFrontier
Deal found 3/31$95
This Cheapflightsfares deal was found by Cheapflights users on 3/30. 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.
Fri 5/28:11 pmDEN - ORD
Nonstop2h 30mFrontier
Mon 5/55:21 pmORD - DEN
Nonstop3h 02mFrontier
Deal found 3/30$97
This Cheapflightsfares deal was found by Cheapflights users on 3/30. 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 5/106:50 amDEN - STL
Nonstop2h 09mFrontier
Sat 5/178:15 pmSTL - DEN
Nonstop2h 33mFrontier
Deal found 3/30$127
This American Airlines deal was found by Cheapflights users on 3/30. 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.
Wed 4/302:00 pmDEN - ORD
Nonstop2h 33mAmerican Airlines
Wed 4/308:39 pmORD - DEN
Nonstop3h 00mAmerican Airlines
Deal found 3/30$154
This Southwest deal was found by Cheapflights users on 3/30. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/115:30 amDEN - MDW
Nonstop2h 25mSouthwest
Tue 6/179:10 amMDW - DEN
Nonstop2h 40mSouthwest
Deal found 3/30$159
This United Airlines deal was found by Cheapflights users on 3/30. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/249:05 pmDEN - ORD
Nonstop2h 30mUnited Airlines
Mon 4/287:10 amORD - DEN
Nonstop2h 54mUnited Airlines
Deal found 3/30$169
This Booking.com deal was found by Cheapflights users on 3/30. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/106:50 amDEN - STL
Nonstop2h 09mMultiple Airlines
Sun 5/2510:20 amSTL - DEN
1 stop8h 07mMultiple Airlines
Deal found 3/30$173
This Southwest deal was found by Cheapflights users on 3/30. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/111:35 pmDEN - ORD
1 stop11h 15mSouthwest
Mon 5/57:00 amORD - DEN
Nonstop2h 40mSouthwest
Deal found 3/30$185
This CheapOair deal was found by Cheapflights users on 3/30. 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.
Thu 5/86:30 pmDEN - ORD
1 stop23h 39mMultiple Airlines
Sun 5/115:21 pmORD - DEN
Nonstop3h 02mMultiple Airlines
Deal found 3/30$202
This Southwest deal was found by Cheapflights users on 3/29. 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.
Sat 5/36:40 amDEN - STL
Nonstop2h 05mSouthwest
Mon 5/55:05 amSTL - DEN
1 stop4h 55mSouthwest
Deal found 3/29$207
This American Airlines deal was found by Cheapflights users on 3/30. 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.
Wed 6/258:22 amDEN - MLI
1 stop6h 02mAmerican Airlines
Wed 7/911:23 amMLI - DEN
1 stop6h 19mAmerican Airlines
Deal found 3/30$209

Cheapflights Fare Finder

Customize your flight search to find flights from Colorado to Illinois 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 March 31, 2025.
Use the filters below to find and compare flights from Colorado to Illinois that are best for you.

Fly from

Colorado

Fly to

Illinois

Route

Depart

Return

Price

DenverPeoria

DEN - PIA

DENPIA

Denver Intl

Fri 5/2

5:17 pm-8:17 pm

Nonstop2h 00m

Greater Peoria

Fri 5/9

3:08 pm-4:27 pm

Nonstop2h 19m

$92

DenverChicago

DEN - MDW

DENMDW

Denver Intl

Sat 4/19

8:55 pm-12:21 am

Nonstop2h 26m

Chicago Midway

Tue 4/22

6:45 am-8:35 am

Nonstop2h 50m

$95

DenverChicago

DEN - ORD

DENORD

Denver Intl

Fri 5/2

8:11 pm-11:41 pm

Nonstop2h 30m

Chicago O'Hare Intl

Mon 5/5

5:21 pm-7:23 pm

Nonstop3h 02m

$97

DenverSt. Louis

DEN - STL

DENSTL

Denver Intl

Sat 5/10

6:50 am-9:59 am

Nonstop2h 09m

Lambert-St Louis

Sat 5/17

8:15 pm-9:48 pm

Nonstop2h 33m

$127

DenverChicago

DEN - ORD

DENORD

Denver Intl

Wed 4/30

2:00 pm-5:33 pm

Nonstop2h 33m

Chicago O'Hare Intl

Wed 4/30

8:39 pm-10:39 pm

Nonstop3h 00m

$154

DenverChicago

DEN - MDW

DENMDW

Denver Intl

Wed 6/11

5:30 am-8:55 am

Nonstop2h 25m

Chicago Midway

Wed 6/18

9:25 pm-11:10 pm

Nonstop2h 45m

$159

DenverChicago

DEN - ORD

DENORD

Denver Intl

Thu 4/24

9:05 pm-12:35 am

Nonstop2h 30m

Chicago O'Hare Intl

Mon 4/28

7:10 am-9:04 am

Nonstop2h 54m

$169

DenverSt. Louis

DEN - STL

DENSTL

Denver Intl

Sat 5/10

6:50 am-9:59 am

Nonstop2h 09m

Lambert-St Louis

Sun 5/25

10:20 am-5:27 pm

1 stop8h 07m

$173

DenverChicago

DEN - ORD

DENORD

Denver Intl

Thu 5/1

11:35 pm-11:50 am

1 stop11h 15m

Chicago O'Hare Intl

Mon 5/5

7:00 am-8:40 am

Nonstop2h 40m

$185

DenverSt. Louis

DEN - STL

DENSTL

Denver Intl

Sat 5/3

6:40 am-9:45 am

Nonstop2h 05m

Lambert-St Louis

Mon 5/5

6:55 pm-8:15 pm

Nonstop2h 20m

$197

Flights are sorted by cheapest round-trip flights first.

Deals found on 3/30

Showing 1-10 of 60 results
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Best time to book a flight from Colorado to Illinois

Have a flexible travel schedule? Discover the best time to fly to Illinois from Colorado 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 Colorado to Illinois

What is the cheapest month to book a flight from Colorado to Illinois?

Currently, August is the cheapest month in which you can book a flight from Colorado to Illinois (average of $245). Flying from Colorado to Illinois in March is currently the most expensive (average of $323). 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 CO to IL?

Find hourly flight availability from Colorado to Illinois. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated March 31, 2025.

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

Weekly flight availability from Colorado to Illinois

Explore weekly flight availability from Colorado to Illinois. 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 March 31, 2025.

The most flights from USCO to USIL are scheduled on a Sunday (55 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (19 on average).

Rainfall in Illinois by month

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

In terms of precipitation, rainfall in Illinois ranges from 1.7 - 4.9 inches per month. August is typically the wettest month, when rainfall can reach 4.9 in. January is typically the driest time to visit Illinois when rainfall is around 1.7 in.

Temperature in Illinois by month

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

If weather is an important factor for your trip to Illinois, 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 23.0 F).

Reviews of airlines servicing Illinois

Get insights into the airlines that provide service to Illinois. 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 Illinois. Reviews last updated March 31, 2025.
Read through reviews of airlines operating flights from Colorado to Illinois, such as Alaska Airlines, Southwest and Delta. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
9,818 reviews

Food

7.1

Comfort

7.9

Overall

8.0

Crew

8.5

Entertainment

7.1

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
9,818 reviews
Alaska Airlines
8.0
Very good
9,818 reviews

Food

7.1

Comfort

7.9

Overall

8.0

Crew

8.5

Entertainment

7.1

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
4,275 reviews
Alaska Airlines
8.0
Very good
9,818 reviews

Food

7.1

Comfort

7.9

Overall

8.0

Crew

8.5

Entertainment

7.1

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
7,899 reviews
Alaska Airlines
8.0
Very good
9,818 reviews

Food

7.1

Comfort

7.9

Overall

8.0

Crew

8.5

Entertainment

7.1

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
8,614 reviews
Alaska Airlines
8.0
Very good
9,818 reviews

Food

7.1

Comfort

7.9

Overall

8.0

Crew

8.5

Entertainment

7.1

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
9,818 reviews

Food

7.1

Comfort

7.9

Overall

8.0

Crew

8.5

Entertainment

7.1

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 Colorado to Illinois. 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 Colorado to Illinois one-way?

    The cheapest airline one-way is Frontier, with whom users have recently found tickets for as low as $48. However, be on the lookout for offers from Allegiant Air and Southwest, as they are both options that can get you from Colorado to Illinois for a low price.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from Colorado to Illinois 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 Colorado to Illinois?

    Currently, August is the cheapest month in which you can book a flight from Colorado to Illinois (average of $245). Flying from Colorado to Illinois in March is currently the most expensive (average of $323). 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 Colorado to Illinois

See prices for flight routes from nearby airports that may be better suited for you.
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Top 5 airlines flying from Colorado to Illinois

Discover the top 5 airlines that operate flights from Colorado to Illinois. 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 March 31, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$44Average$147FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$84Average$165FlexibilityNo cancel feeOn-time88%
American AirlinesCheapest$148Average$445FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$149Average$455FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$155Average$298FlexibilityNo cancel feeOn-time63%
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