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$44+ Cheap flights from Illinois to Denver (DEN)

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 3/4. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Nov 21 — Nov 281
Fri 11/21
Fri 11/28
1 adult, Economy
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Cheap flight deals from Illinois to Denver

Keep the following information in mind while searching for Illinois to Denver flight deals. Data was last updated October 22, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$71
(Kiwi.com)

One-way from

$44
(Frontier)

Popular in

December

Cheapest in

November

Average price

$197

Good round-trip deal

$154 or less

Good one-way deal

$106 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 Denver Intl
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One-way flight from Illinois to Denver Intl
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High demand for flights, 2% potential price rise
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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 October 2025
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Price to beat on a round-trip flight from Illinois to Denver Intl.
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Price to beat on a one-way flight from Illinois to Denver Intl.
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Find flight deals from Illinois to Denver

Cheapest flights from Illinois to Denver
Explore the most affordable flight options available from Illinois to Denver. Find the lowest fares from popular airlines and budget airlines, with prices last updated on October 22, 2025.

This Frontier deal was found by Cheapflights users on 10/20. 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.
Tue 10/288:40 pmSTL - DEN
Nonstop2h 30mFrontier
Wed 10/296:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 10/20$68
This Frontier deal was found by Cheapflights users on 10/21. 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 12/247:43 pmSTL - DEN
Nonstop2h 32mFrontier
Wed 12/316:50 amDEN - STL
Nonstop2h 12mFrontier
Deal found 10/21$80
This Priceline deal was found by Cheapflights users on 10/20. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/157:45 pmSTL - DEN
Nonstop2h 28mFrontier
Mon 11/176:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 10/20$84
This Frontier deal was found by Cheapflights users on 10/20. 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.
Tue 10/288:40 pmSTL - DEN
Nonstop2h 30mFrontier
Sun 11/96:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 10/20$85
This Frontier deal was found by Cheapflights users on 10/20. 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.
Wed 11/127:45 pmSTL - DEN
Nonstop2h 28mFrontier
Fri 11/146:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 10/20$88
This Kiwi.com deal was found by Cheapflights users on 10/20. 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.
Sat 11/18:40 pmSTL - DEN
Nonstop2h 30mFrontier
Thu 11/66:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 10/20$90
This Cheapflightsfares deal was found by Cheapflights users on 10/20. 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 10/277:52 pmSTL - DEN
Nonstop2h 28mFrontier
Wed 10/296:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 10/20$91
This Kiwi.com deal was found by Cheapflights users on 10/20. 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.
Tue 11/118:28 amORD - DEN
1 stop8h 25mMultiple Airlines
Tue 11/184:00 pmDEN - ORD
Nonstop2h 38mMultiple Airlines
Deal found 10/20$92
This Priceline deal was found by Cheapflights users on 10/22. 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.
Tue 11/117:45 pmSTL - DEN
Nonstop2h 28mFrontier
Mon 11/176:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 10/22$92
This Frontier deal was found by Cheapflights users on 10/21. 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 11/136:00 amORD - DEN
Nonstop2h 41mFrontier
Sat 11/157:59 pmDEN - ORD
Nonstop2h 30mFrontier
Deal found 10/21$93
This Priceline deal was found by Cheapflights users on 10/20. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/3112:30 pmMDW - DEN
Nonstop2h 46mFrontier
Sun 11/28:05 amDEN - MDW
Nonstop2h 25mFrontier
Deal found 10/20$93
This Frontier deal was found by Cheapflights users on 10/21. 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.
Sun 11/166:00 amORD - DEN
Nonstop2h 41mFrontier
Sun 12/78:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 10/21$94

Cheapflights Fare Finder

 
Customize your flight search to find flights from Illinois to Denver 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 October 22, 2025.
Use the filters below to find and compare flights from Illinois to Denver that are best for you.

Fly from

Illinois

Fly to

Denver

Route

Depart

Return

Price

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Fri 12/12

7:43 pm-9:15 pm

Nonstop2h 32m

Denver Intl

Mon 12/15

11:59 pm-10:33 pm

1 stop21h 34m

$108

PeoriaDenver

PIA - DEN

PIADEN

Greater Peoria

Fri 12/12

3:08 pm-4:34 pm

Nonstop2h 26m

Denver Intl

Mon 12/15

5:24 pm-8:21 pm

Nonstop1h 57m

$123

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Sat 2/7

4:15 pm-5:53 pm

Nonstop2h 38m

Denver Intl

Tue 2/10

5:50 pm-8:58 pm

Nonstop2h 08m

$145

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Thu 11/13

6:22 pm-11:12 pm

1 stop5h 50m

Denver Intl

Sun 11/16

10:29 pm-11:24 am

1 stop11h 55m

$163

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Thu 2/26

9:05 pm-10:56 pm

Nonstop2h 51m

Denver Intl

Mon 3/2

7:23 pm-10:52 pm

Nonstop2h 29m

$167

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Sat 12/6

3:35 pm-11:44 am

1 stop21h 09m

Denver Intl

Sat 12/13

11:41 am-6:21 am

2 stops17h 40m

$172

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Mon 2/2

8:45 am-10:21 am

Nonstop2h 36m

Denver Intl

Mon 2/2

5:50 pm-8:58 pm

Nonstop2h 08m

$174

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Mon 2/2

8:45 am-10:21 am

Nonstop2h 36m

Denver Intl

Sun 2/8

1:41 pm-4:43 pm

Nonstop2h 02m

$174

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Wed 1/14

3:25 pm-6:41 pm

1 stop28h 16m

Denver Intl

Tue 1/20

12:34 pm-11:37 pm

1 stop10h 03m

$176

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Sat 1/31

7:00 am-12:03 pm

1 stop6h 03m

Denver Intl

Mon 2/2

12:59 am-9:04 am

1 stop7h 05m

$177

Flights are sorted by cheapest round-trip flights first.

Deals found on 10/22

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

Have a flexible travel schedule? Discover the best time to fly to Denver 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 Denver

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

Currently, September is the cheapest month in which you can book a flight from Illinois to Denver (average of $49). Flying from Illinois to Denver in July is currently the most expensive (average of $112). 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 DEN?

Find hourly flight availability from Illinois to Denver. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated October 22, 2025.

A simple way to save on the total cost of your ticket is to fly from Illinois to Denver in the evening. If you’re flexible enough to do this you can expect to save up to 45% on your trip compared to booking a flight at noon.

What is the cheapest day to fly from Illinois to Denver?

Use this chart to determine the cheapest time to fly round-trip from Illinois to Denver. Price data was last updated on December 16, 2024.

Travelers seeking maximum savings on their Illinois to Denver 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.

Weekly flight availability from Illinois to Denver

Explore weekly flight availability from Illinois to Denver. 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 October 22, 2025.

The most flights from USIL to DEN are scheduled on a Wednesday (62 on average). You will have fewer flight options on Sunday, which is when the least amount of flights are scheduled (13 on average).

Related info for your journey

Find useful and relevant information for your journey from Illinois to Denver. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly into for flights to Denver from Illinois?

    For a flight from Illinois to Denver, you will be flying into Denver Intl. Denver Intl (DEN) is just 18.5 mi from the center of the city.

  • How long is the flight from Illinois to Denver?

    Airlines like Frontier, Allegiant Air, and United Airlines fly from Illinois to Denver in about 2h 26m. The time it takes to get you to your destination is usually consistent. Airlines will cover a distance of 790 mi. All flights are typically nonstop.

  • What are the cheapest airlines to fly from Illinois to Denver one-way?

    The cheapest airlines for a one-way flight from Illinois to Denver are Frontier ($55), Allegiant Air ($69), and Southwest ($71).

  • What are the most popular routes from Illinois to Denver?

    While some choose either Lambert-St Louis - Denver Intl or Chicago Midway - Denver Intl, Chicago O'Hare Intl - Denver Intl is the most popular route from Illinois to Denver.

  • What are the most reliable airlines from Illinois to Denver?

    The top 3 most reliable airlines when flying from Illinois to Denver are Frontier (83%), Southwest (80%) and Copa Airlines (79%).

  • What are the cheapest flights from Illinois to Denver?

    While on average a flight from Illinois to Denver is generally $608, our data shows the cheapest flight currently is $78. When looking at the most popular route, (Chicago O'Hare Intl - Denver Intl), you can expect to pay $82 for that flight.

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

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

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

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

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

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

    Currently, September is the cheapest month in which you can book a flight from Illinois to Denver (average of $49). Flying from Illinois to Denver in July is currently the most expensive (average of $112). 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

Traveling to a place near Denver?

Book flights to Denver if you plan to visit one of these locations
Black Hawk
Westminster
Broomfield
Lakewood
Golden
Winter Park
Greeley
Lone Tree
Cripple Creek
Thornton
Silverthorne
Central City
Manitou Springs
Fort Morgan
Wheat Ridge
Brighton
Longmont
Idaho Springs
Parker
Sterling

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Alternative routes for Illinois to Denver

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 Denver

Discover the top 6 airlines that operate flights from Illinois to Denver. 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 October 22, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$59Average$159FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$77Average$140FlexibilityNo cancel feeOn-time88%
American AirlinesCheapest$152Average$375FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$157Average$251FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$159Average$357FlexibilityNo cancel feeOn-time69%
DeltaCheapest$228Average$248FlexibilityNo cancel feeOn-timeN/A

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