HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Colorado

$64+ 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 10/15. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Oct 15 — Oct 221
Wed 10/15
Wed 10/22
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from Illinois to Colorado with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.

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 September 15, 2025.

Round-trip from

$92
(Flightnetwork)

One-way from

$64
(United Airlines)

Popular in

December

Cheapest in

November

Average price

$181

Good round-trip deal

$151 or less

Good one-way deal

$101 or less
From Illinois to Colorado
Search Deals
One-way flight from Illinois to Colorado
Search Deals
High demand for flights, 1% potential price rise
Search Deals
Cheapest flight prices on average. 1% potential price decrease ($4 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in September 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

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 September 15, 2025.

This Cheapflightsfares deal was found by Cheapflights users on 9/15. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/307:55 pmSTL - DEN
Nonstop2h 25mFrontier
Mon 10/66:00 amDEN - STL
Nonstop2h 06mFrontier
Deal found 9/15$84
This Flightnetwork deal was found by Cheapflights users on 9/13. 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 Flightnetwork is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/308:40 pmSTL - DEN
Nonstop2h 30mFrontier
Sun 11/25:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 9/13$92
This Frontier deal was found by Cheapflights users on 9/14. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/17:55 pmSTL - DEN
Nonstop2h 25mFrontier
Sun 10/56:00 amDEN - STL
Nonstop2h 06mFrontier
Deal found 9/14$95
This Cheapflightsfares deal was found by Cheapflights users on 9/13. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/137:45 pmSTL - DEN
Nonstop2h 28mFrontier
Sun 11/166:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 9/13$96
This CheapOair deal was found by Cheapflights users on 9/13. 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.
Sat 10/48:25 amORD - DEN
Nonstop2h 51mFrontier
Tue 10/78:22 pmDEN - ORD
Nonstop2h 31mFrontier
Deal found 9/13$98
This Cheapflightsfares deal was found by Cheapflights users on 9/14. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/237:52 pmSTL - DEN
Nonstop2h 28mFrontier
Sun 10/266:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 9/14$99
This Priceline deal was found by Cheapflights users on 9/14. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/247:52 pmSTL - DEN
Nonstop2h 28mFrontier
Sun 10/266:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 9/14$100
This Cheapflightsfares deal was found by Cheapflights users on 9/13. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/137:52 pmSTL - DEN
Nonstop2h 28mFrontier
Fri 10/176:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 9/13$101
This Cheapflightsfares deal was found by Cheapflights users on 9/13. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/87:39 pmORD - DEN
Nonstop2h 59mFrontier
Sat 12/132:59 pmDEN - ORD
Nonstop2h 35mFrontier
Deal found 9/13$102
This Frontier deal was found by Cheapflights users on 9/14. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/2412:11 pmMDW - DEN
Nonstop2h 46mFrontier
Sat 10/2512:25 pmDEN - MDW
1 stop9h 22mFrontier
Deal found 9/14$104
This Cheapflightsfares deal was found by Cheapflights users on 9/13. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/25:35 amORD - DEN
Nonstop2h 45mFrontier
Sat 10/118:22 pmDEN - ORD
Nonstop2h 31mFrontier
Deal found 9/13$105
This Cheapflightsfares deal was found by Cheapflights users on 9/13. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/316:00 amORD - DEN
Nonstop2h 41mFrontier
Sun 11/28:41 pmDEN - ORD
Nonstop2h 31mFrontier
Deal found 9/13$106

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 September 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 10/15

7:52 pm-9:20 pm

Nonstop2h 28m

Denver Intl

Sun 10/19

10:29 pm-11:43 am

1 stop12h 14m

$112

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Fri 11/7

1:36 pm-8:37 am

1 stop20h 01m

Denver Intl

Fri 11/14

8:44 pm-12:15 am

Nonstop2h 31m

$114

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Thu 11/20

9:00 am-10:30 am

Nonstop2h 30m

Denver Intl

Sun 11/23

6:50 pm-9:54 pm

Nonstop2h 04m

$131

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Tue 11/25

9:00 am-10:30 am

Nonstop2h 30m

Denver Intl

Sat 11/29

8:40 pm-11:44 pm

Nonstop2h 04m

$131

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Thu 10/16

5:15 am-6:53 am

Nonstop2h 38m

Denver Intl

Tue 10/21

8:45 pm-11:58 pm

Nonstop2h 13m

$131

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Fri 10/17

6:24 pm-8:08 pm

Nonstop2h 44m

Denver Intl

Sun 10/19

9:12 pm-12:36 am

Nonstop2h 24m

$138

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Tue 12/23

4:15 pm-6:55 pm

1 stop3h 40m

Denver Intl

Tue 12/30

5:10 am-8:15 am

Nonstop2h 05m

$141

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Tue 10/21

4:35 pm-6:15 pm

Nonstop2h 40m

Denver Intl

Thu 10/23

5:30 pm-8:50 pm

Nonstop2h 20m

$142

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Sat 10/4

5:25 pm-7:10 pm

Nonstop2h 45m

Denver Intl

Tue 10/7

10:15 am-9:30 pm

2 stops10h 15m

$142

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Thu 12/11

1:35 pm-3:05 pm

Nonstop2h 30m

Denver Intl

Mon 12/15

5:53 pm-8:57 pm

Nonstop2h 04m

$144

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/14

Showing 1-10 of 60 results
1
2
3
...
6

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 September 15, 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 September 15, 2025.

The most flights from USIL to USCO are scheduled on a Sunday (64 on average). You will have fewer flight options on Wednesday, which is when the least amount of flights are scheduled (50 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 September 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
8.0
Very good
4,245 reviews

Entertainment

7.5

Overall

8.0

Crew

8.6

Food

7.0

Comfort

8.0

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Southwest
8.0
Very good
4,245 reviews
Southwest
8.0
Very good
4,245 reviews

Entertainment

7.5

Overall

8.0

Crew

8.6

Food

7.0

Comfort

8.0

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
United Airlines
7.4
Good
8,931 reviews
Southwest
8.0
Very good
4,245 reviews

Entertainment

7.5

Overall

8.0

Crew

8.6

Food

7.0

Comfort

8.0

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
American Airlines
7.2
Good
10,000 reviews
Southwest
8.0
Very good
4,245 reviews

Entertainment

7.5

Overall

8.0

Crew

8.6

Food

7.0

Comfort

8.0

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Allegiant Air
7.2
Good
699 reviews
Southwest
8.0
Very good
4,245 reviews

Entertainment

7.5

Overall

8.0

Crew

8.6

Food

7.0

Comfort

8.0

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Frontier
5.8
Fair
3,173 reviews
Southwest
8.0
Very good
4,245 reviews

Entertainment

7.5

Overall

8.0

Crew

8.6

Food

7.0

Comfort

8.0

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.

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 Frontier, United Airlines, and Southwest fly from Illinois to Colorado in about 2h 28m. The time it takes to get you to your destination can typically vary by up to 1h 12m. 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 $66 on United Airlines. Other airlines that offer cheap prices include Southwest from $74 and Allegiant Air from $81 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

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Illinois to Colorado

See prices for flight routes from nearby airports that may be better suited for you.
Los Angeles to John F Kennedy Intl flights
John F Kennedy Intl to Los Angeles flights
Dallas/Fort Worth to Las Vegas flights
LaGuardia to Dallas/Fort Worth flights
John F Kennedy Intl to Las Vegas flights
Dallas/Fort Worth to John F Kennedy Intl flights
John F Kennedy Intl to O'Hare Intl flights
John F Kennedy Intl to Miami flights
Dallas/Fort Worth to O'Hare Intl flights
Newark to Fort Lauderdale flights
San Francisco to John F Kennedy Intl flights
Dallas/Fort Worth to LaGuardia flights
LaGuardia to O'Hare Intl flights
Newark to Las Vegas flights
Seattle to Las Vegas flights
O'Hare Intl to LaGuardia flights
Newark to O'Hare Intl flights
LaGuardia to Fort Lauderdale flights
Newark to Miami flights
Los Angeles to Newark flights
LaGuardia to Miami flights
Seattle to Los Angeles flights
O'Hare Intl to Las Vegas flights
John F Kennedy Intl to Dallas/Fort Worth flights
Dallas/Fort Worth to Los Angeles flights
O'Hare Intl to John F Kennedy Intl flights
Los Angeles to Dallas/Fort Worth flights
Newark to Dallas/Fort Worth flights
John F Kennedy Intl to Atlanta flights
O'Hare Intl to Newark flights
John F Kennedy Intl to San Francisco flights
Los Angeles to Seattle flights
O'Hare Intl to Dallas/Fort Worth flights
Seattle to Dallas/Fort Worth flights
Dallas/Fort Worth to Denver flights
Dallas/Fort Worth to Newark flights
Dallas/Fort Worth to Seattle flights
San Francisco to Las Vegas flights
John F Kennedy Intl to Orlando flights
Los Angeles to San Francisco flights
Los Angeles to O'Hare Intl flights
Los Angeles to LaGuardia flights
San Francisco to Newark flights
Newark to Los Angeles flights
Atlanta to LaGuardia flights
Newark to San Francisco flights
Dulles Intl to Dallas/Fort Worth flights
John F Kennedy Intl to Fort Lauderdale flights
LaGuardia to Los Angeles flights
Newark to Orlando flights

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 September 15, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$57Average$155FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$81Average$143FlexibilityNo cancel feeOn-time88%
American AirlinesCheapest$153Average$416FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$157Average$340FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$161Average$471FlexibilityNo cancel feeOn-time69%
DeltaCheapest$228Average$248FlexibilityNo cancel feeOn-timeN/A

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.