HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Denver

$69+ 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 11/9. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Aug 23 — Aug 301
Sat 8/23
Sat 8/30
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from Illinois to Denver 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 Denver

Keep the following information in mind while searching for Illinois to Denver flight deals. Data was last updated August 18, 2025.

Round-trip from

$99
(Cheapflightsfares)

One-way from

$69
(Cheapflightsfares)

Popular in

December

Cheapest in

November

Average price

$199

Good round-trip deal

$161 or less

Good one-way deal

$98 or less
From Illinois to Denver Intl
Search Deals
One-way flight from Illinois to Denver Intl
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 August 2025
Search Deals
Price to beat on a round-trip flight from Illinois to Denver Intl.
Search Deals
Price to beat on a one-way flight from Illinois to Denver Intl.
Search Deals

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 August 18, 2025.

This Cheapflightsfares deal was found by Cheapflights users on 8/16. 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 9/57:55 pmSTL - DEN
Nonstop2h 25mFrontier
Tue 9/96:00 amDEN - STL
Nonstop2h 06mFrontier
Deal found 8/16$99
This Cheapflightsfares deal was found by Cheapflights users on 8/16. 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 9/47:55 pmSTL - DEN
Nonstop2h 25mFrontier
Tue 9/96:00 amDEN - STL
Nonstop2h 06mFrontier
Deal found 8/16$100
This Cheapflightsfares deal was found by Cheapflights users on 8/17. 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 9/197:55 pmSTL - DEN
Nonstop2h 25mFrontier
Sat 9/276:00 amDEN - STL
Nonstop2h 06mFrontier
Deal found 8/17$101
This Cheapflightsfares deal was found by Cheapflights users on 8/16. 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 9/83:18 pmPIA - DEN
Nonstop2h 16mAllegiant Air
Fri 9/195:24 pmDEN - PIA
Nonstop2h 00mAllegiant Air
Deal found 8/16$102
This Cheapflightsfares deal was found by Cheapflights users on 8/15. 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.
Fri 9/57:55 pmSTL - DEN
Nonstop2h 25mFrontier
Sun 9/76:00 amDEN - STL
Nonstop2h 06mFrontier
Deal found 8/15$103
This Cheapflightsfares deal was found by Cheapflights users on 8/17. 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 9/117:55 pmSTL - DEN
Nonstop2h 25mFrontier
Mon 9/156:00 amDEN - STL
Nonstop2h 06mFrontier
Deal found 8/17$104
This Cheapflightsfares deal was found by Cheapflights users on 8/17. 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 11/37:45 pmSTL - DEN
Nonstop2h 28mFrontier
Fri 11/76:00 amDEN - STL
Nonstop2h 07mFrontier
Deal found 8/17$105
This Cheapflightsfares deal was found by Cheapflights users on 8/18. 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 8/18$106
This Cheapflightsfares deal was found by Cheapflights users on 8/16. 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 9/127:55 pmSTL - DEN
Nonstop2h 25mFrontier
Mon 9/156:00 amDEN - STL
Nonstop2h 06mFrontier
Deal found 8/16$108
This Cheapflightsfares deal was found by Cheapflights users on 8/17. 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 10/3012:30 pmMDW - DEN
Nonstop2h 46mFrontier
Sun 11/28:05 amDEN - MDW
Nonstop2h 25mFrontier
Deal found 8/17$109
This Kiwi.com deal was found by Cheapflights users on 8/18. 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.
Sun 8/317:54 pmSTL - DEN
Nonstop2h 29mFrontier
Sun 9/76:00 amDEN - STL
Nonstop2h 06mFrontier
Deal found 8/18$109
This FlightHub deal was found by Cheapflights users on 8/16. 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.
Fri 10/36:00 amORD - DEN
Nonstop2h 45mFrontier
Mon 10/66:00 amDEN - ORD
Nonstop2h 37mFrontier
Deal found 8/16$109

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 August 18, 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 9/5

7:55 pm-9:20 pm

Nonstop2h 25m

Denver Intl

Mon 9/8

6:00 am-9:06 am

Nonstop2h 06m

$99

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Fri 9/5

7:55 pm-9:20 pm

Nonstop2h 25m

Denver Intl

Tue 9/9

6:00 am-9:06 am

Nonstop2h 06m

$99

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Mon 9/8

7:55 pm-9:20 pm

Nonstop2h 25m

Denver Intl

Sat 9/13

6:00 am-9:06 am

Nonstop2h 06m

$99

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Thu 9/4

7:55 pm-9:20 pm

Nonstop2h 25m

Denver Intl

Tue 9/9

6:00 am-9:06 am

Nonstop2h 06m

$100

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Thu 9/4

7:55 pm-9:20 pm

Nonstop2h 25m

Denver Intl

Mon 9/8

6:00 am-9:06 am

Nonstop2h 06m

$100

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Tue 9/16

7:55 pm-9:20 pm

Nonstop2h 25m

Denver Intl

Thu 9/18

6:00 am-9:06 am

Nonstop2h 06m

$101

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 9/17

7:55 pm-9:20 pm

Nonstop2h 25m

Denver Intl

Fri 9/19

6:00 am-9:06 am

Nonstop2h 06m

$101

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 10/1

7:55 pm-9:20 pm

Nonstop2h 25m

Denver Intl

Fri 10/31

6:00 am-9:07 am

Nonstop2h 07m

$101

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Fri 9/19

7:55 pm-9:20 pm

Nonstop2h 25m

Denver Intl

Wed 9/24

6:00 am-9:06 am

Nonstop2h 06m

$101

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 9/24

7:55 pm-9:20 pm

Nonstop2h 25m

Denver Intl

Sun 9/28

6:00 am-9:06 am

Nonstop2h 06m

$101

Flights are sorted by cheapest round-trip flights first.

Deals found on 8/17

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

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, October is the cheapest month in which you can book a flight from Illinois to Denver (average of $197). Flying from Illinois to Denver 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 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 August 18, 2025.

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

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 August 18, 2025.

The most flights from USIL to DEN are scheduled on a Sunday (62 on average). You will have fewer flight options on Wednesday, which is when the least amount of flights are scheduled (17 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 16m. 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 most popular routes from Illinois to Denver?

    While some choose either Chicago Midway - Denver Intl or Lambert-St Louis - 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 United Airlines (74%), Southwest (71%) and Iberia (68%).

  • What are the cheapest flights from Illinois to Denver?

    While on average a flight from Illinois to Denver is generally $457, our data shows the cheapest flight currently is $68. When looking at the most popular route, (Chicago O'Hare Intl - Denver Intl), you can expect to pay $71 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, October is the cheapest month in which you can book a flight from Illinois to Denver (average of $197). Flying from Illinois to Denver 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

Traveling to a place near Denver?

Book flights to Denver if you plan to visit one of these locations
Westminster
Black Hawk
Golden
Winter Park
Greeley
Lone Tree
Lakewood
Cripple Creek
Silverthorne
Thornton
Broomfield
Frisco
Manitou Springs
Grand Lake
Fort Morgan
Glendale
Copper Mountain
Wheat Ridge
Brighton
Longmont

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 Denver

See prices for flight routes from nearby airports that may be better suited for you.
Dallas/Fort Worth to Denver flights
John F Kennedy Intl to Denver flights
LaGuardia to Denver flights
Newark to Denver flights
Hobby to Denver flights
Los Angeles to Denver flights
Philadelphia to Denver flights
Seattle to Denver flights
Atlanta to Denver flights
O'Hare Intl to Denver flights
Baltimore to Denver flights
George Bush Intcntl to Denver flights
Boston to Denver flights
San Francisco to Denver flights
Minneapolis to Denver flights
Ontario to Denver flights
Reagan-National to Denver flights
Dulles Intl to Denver flights
Orlando to Denver flights
Raleigh to Denver flights
Austin to Denver flights
Charlotte to Denver flights
Sky Harbor Intl to Denver flights
Miami to Denver flights
Detroit to Denver flights
Cincinnati to Denver flights
Santa Ana to Denver flights
Fort Lauderdale to Denver flights
Tampa to Denver flights
Midway to Denver flights
Cleveland to Denver flights
San Jose to Denver flights
Portland to Denver flights
Indianapolis to Denver flights
Love Field to Denver flights
Kansas City to Denver flights
San Diego to Denver flights
Milwaukee to Denver flights
Grand Rapids to Denver flights
Madison to Denver flights
Hartford to Denver flights
Nashville to Denver flights
Syracuse to Denver flights
Pittsburgh to Denver flights
San Antonio to Denver flights
Columbus to Denver flights
Las Vegas to Denver flights
Sacramento to Denver flights
Oklahoma City to Denver flights
Greenville to Denver flights

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 August 18, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$56Average$158FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$81Average$143FlexibilityNo cancel feeOn-time88%
American AirlinesCheapest$152Average$374FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$157Average$256FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$161Average$356FlexibilityNo 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.